Microbial Viability Research Papers - Academia.edu (original) (raw)

2025, Letters in applied microbiology

The aim of this work was to evaluate the changes due to acclimation to ethanol on the fatty acid composition of three oenological Lactobacillus plantarum strains and their effect on the resistance to ethanol and malic acid consumption (MAC). Lactobacillus plantarum UNQLp 133, UNQLp 65.3 and UNQLp 155 were acclimated in the presence of 6 or 10% v/v ethanol, for 48 h at 28°C. Lipids were extracted to obtain fatty acid methyl esters and analysed by gas chromatography interfaced with mass spectroscopy. The influence of change in fatty acid composition on the viability and MAC in synthetic wine was analysed by determining the Pearson correlation coefficient. Acclimated strains showed a significant change in the fatty composition with regard to the nonacclimated strains. Adaptation to ethanol led to a decrease in the unsaturated/saturated ratio, mainly resulting from an increase in the contribution of short-length fatty acid C12:0 and a decrease of C18:1. The content of C12:0 was related ...

2025, International Journal of Food Microbiology

To investigate the survival of E. coli O157:H7 and Salmonella Typhimurium in cowpats on pasture in a temperate Nordic climate.

2025, Vaccine

Mortality associated with influenza virus super-infections is frequently due to secondary bacterial complications. To date, super-infections with Streptococcus pyogenes have been studied less extensively than those associated with S. pneumoniae. This is significant because a vaccine for S. pyogenes is not clinically available, leaving vaccination against influenza virus as our only means for preventing these super-infections. In this study, we directly compared immunity induced by two types of influenza vaccine, either inactivated influenza virus (IIV) or live, attenuated influenza virus (LAIV), for the ability to prevent super-infections. Our data demonstrate that both IIV and LAIV vaccines induce similar levels of serum antibodies, and that LAIV alone induces IgA expression at mucosal surfaces. Upon super-infection, both vaccines have the ability to limit the induction of pro-inflammatory cytokines within the lung, including IFN-γ which has been shown to contribute to mortality in previous models of super-infection. Limiting expression of these proinflammatory cytokines within the lungs subsequently limits recruitment of macrophages and neutrophils to pulmonary surfaces, and ultimately protects both IIV-and LAIV-vaccinated mice from mortality. Despite their overall survival, both IIV-and LAIV-vaccinated mice demonstrated levels of bacteria within the lung tissue to levels that are similar to those seen in unvaccinated mice. Thus, influenza virus:bacteria super-infections can be limited by vaccine-induced immunity against influenza virus, but the ability to prevent morbidity is not complete.

2025

18 The effectiveness of ultraviolet C light (UV-C) delivered in water (WUV) or in peroxyacetic acid (PAA) 19 for the inactivation and inhibition of L. monocytogenes and S. enterica in ready-to-eat ‘Iceberg 20 lettuce’ and baby spinach leaves, was evaluated throughout chilled storage in modified atmosphere 21 packaging (MAP). The inhibition of pathogen’s growth by sequential pretreatments with UV-C in PAA 22

2025, American Journal of Infection Control

Background: Bacterial contamination of surfaces with methicillin-resistant Staphylococcus aureus (MRSA) is a serious problem in the hospital environment and is responsible for significant nosocomial infections. The pathogenic contaminants form biofilms, which are difficult to treat with routine biocides. Thus, a continuous search for novel disinfection methods is essential for effective infection control measures. This demonstration of a novel technique for the control of virulent pathogens in planktonic form as well as in established biofilms may provide a progressive alternative to standard methodology. Methods: We evaluated a novel technique of normal atmospheric nonthermal plasma known as floating-electrode dielectric-barrier discharge (FE-DBD) plasma against a control of planktonic and biofilm forms of Escherichia coli, S aureus, multidrug-resistant methicillin-resistant S aureus (MRSA) -95 (clinical isolate), -USA300, and -USA400, using widely accepted techniques such as colony count assay, LIVE/DEAD BacLight Bacterial Viability assay, and XTT (2,3-Bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) assay. Results: Exposure of free living planktonic forms of E coli, S aureus, and MRSAwere rapidly inactivated by DBD plasma. Approximately 10 7 bacterial cells were completely (100%) killed, whereas 10 8 and 10 9 were reduced by approximately 90% to 95% and 40% to 45%, respectively, in less than 60 seconds (7.8 J/cm 2 ) and completely disinfected in #120 seconds. In established biofilms, the susceptibility of MRSA USA400 was comparable with USA300 but less susceptible than MRSA95 (clinical isolate), S aureus, and E coli (P , .05) to FE-DBD plasma, and plasma was able to kill MRSA more than 60% within 15 seconds (1.95 J/cm 2 ). The killing responses were plasma exposure-time dependent, and cell density dependent. The plasma was able disinfect surfaces in a less than 120 seconds. Conclusion: Application of DBD plasma can be a valuable decontamination technique for the removal of planktonic and biofilmembedded bacteria such as MRSA -USA 300, -USA 400, methicillin-sensitive S aureus (MSSA), and E coli, the more common hospital contaminants. Of interest, E coli was more resistant than S aureus phenotypes.

2025, Journal of Microbiological Methods

Bacterial and archaeal genomes can contain 30% or more hypothetical genes with no predicted function. Phylogenetically deep-branching microbes, such as methane-producing archaea (methanogens), contain up to 50% genes with unknown function. In order to formulate hypotheses about the function of hypothetical gene functions in the strict anaerobe, Methanosarcina acetivorans, we have developed high-throughput anaerobic techniques to UV mutagenize, screen, and select for mutant strains in 96-well plates. Using these approaches we have isolated 10 mutant strains that exhibit a variety of physiological changes including increased or decreased growth rate relative to the parent strain when cells use methanol and/or acetate as carbon and energy sources. This method provides an avenue for the first step in identifying new gene functions: associating a genetic mutation with a reproducible phenotype. Mutations in bona fide methanogenesis genes such as corrinoid methyltransferases and proton-translocating F420H2:methanophenazine oxidoreductase (Fpo) were also generated, opening the door to in vivo functional complementation experiments. Irradiation-based mutagenesis such as from ultraviolet (UV) light, combined with modern genome sequencing, is a useful procedure to discern systems-level gene function in prokaryote taxa that can be axenically cultured but which may be resistant to chemical mutagens.

2025, Scientific reports

Biological sulfate-reducing bacteria (SRB) may be effective in removing toxic lead and mercury ions (Pb(II) and Hg(II)) from wet flue gas desulfurization (FGD) wastewater through anaerobic sulfite reduction. To confirm this hypothesis, a sulfite-reducing up-flow anaerobic sludge blanket reactor was set up to treat FGD wastewater at metal loading rates of 9.2 g/m(3)-d Pb(II) and 2.6 g/m(3)-d Hg(II) for 50 days. The reactor removed 72.5 ± 7% of sulfite and greater than 99.5% of both Hg(II) and Pb(II). Most of the removed lead and mercury were deposited in the sludge as HgS and PbS. The contribution of cell adsorption and organic binding to Pb(II) and Hg(II) removal was 20.0 ± 0.1% and 1.8 ± 1.0%, respectively. The different bioavailable concentration levels of lead and mercury resulted in different levels of lethal toxicity. Cell viability analysis revealed that Hg(II) was less toxic than Pb(II) to the sludge microorganisms. In the batch tests, increasing the Hg(II) feeding concentrat...

2025, Free Radical Biology and Medicine

Due to their aerobic life style, eukaryotic organisms have evolved different strategies to overcome oxidative stress. The recruitment of some specific metalloenzymes such as superoxide dismutases (SODs) and catalases (CATs) is of great importance to eliminate harmful reactive oxygen species (hydrogen peroxide and superoxide anion). Using the ligand HPClNOL {1-[bis(pyridin-2-ylmethyl)amino]-3-chloropropan-2-ol}, we have synthesized three coordination compounds containing iron(III), copper(II) and manganese(II) ions, which are also present in the active site of the above mentioned metalloenzymes. These compounds were evaluated as SOD and CAT mimetics. The manganese and iron compounds showed both SOD and CAT activities, while copper showed just SOD activity. The copper and manganese in vitro SOD activities are very similar (IC 50 ~ 0.4 µmol dm -3 ) and about 70-fold higher than the iron one. The manganese compound showed CAT activity higher than the iron species. Analyzing their capacity to protect Saccharomyces cerevisiae cells against oxidative stress (H 2 O 2 and the O 2 •-radical), we observed that all compounds act as antioxidants, increasing the resistance of yeast cells mainly due to a reduction of lipid oxidation. Especially for the iron compound, the data indicate complete protection when wild-type cells were exposed to H 2 O 2 or O 2 •-species. Interestingly, these compounds also compensate for both superoxide dismutase and catalase deficiencies; their antioxidant activity is metal ion-dependent, in the order iron(III) > copper(II) > manganese(II). The protection mechanism employed by the complexes proved to be independent of the activation of transcription factors (such as Yap1, Hsf1, Msn2/Msn4) and protein synthesis. There is no direct relation between the in vitro and in vivo antioxidant activities.

2025, Future Microbiology

Aim: To evaluate the antibacterial activity of Thymbra capitata essential oil and its main compound, carvacrol, against Gardnerella vaginalis grown planktonically and as biofilms, and its effect of vaginal lactobacilli. Materials & methods: Minimal inhibitory concentration, minimal lethal concentration determination and flow cytometry analysis were used to assess the antibacterial effect against planktonic cells. Antibiofilm activity was measured through quantification of biomass and visualization of biofilm structure by confocal laser scanning microscopy. Results: T. capitata essential oil and carvacrol exhibited a potent antibacterial activity against G. vaginalis cells. Antibiofilm activity was more evident with the essential oil than carvacrol. Furthermore, vaginal lactobacilli were significantly more tolerant to the essential oil. Conclusion: T. capitata essential oil stands up as a promising therapeutic agent against G. vaginalis biofilm-related infections.

2025, European Journal of Clinical Microbiology & Infectious Diseases

This study evaluates the composition, antifungal activity and mechanism of action of the essential oil of Ferulago capillaris (Link ex Spreng.) Cout. and its main components, limonene and α-pinene, against clinically relevant yeasts and moulds. Essential oil from the plant's aerial parts was obtained by hydrodistillation and analysed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). Essential oil showed high contents of limonene (30.9 %) and α-pinene (35.8 %). Minimum inhibitory concentrations (MICs) were measured according to the reference Clinical and Laboratory Standards Institute (CLSI) broth macrodilution protocols. Cell suspensions were subcultured in solid medium and the minimum fungicidal concentrations (MFCs) were rendered. The effect of essential oil on germ tube formation, mitochondrial function and ergosterol biosynthesis was investigated. Essential oil and α-pinene displayed low and similar MIC and MFC values against tested organisms (0.08 to 5.0 μL/mL), while limonene showed a weaker activity (0.32 to 20 μL/mL). Essential oil inhibited germ tube formation at sub-inhibitory concentrations on Candida albicans. The exposure of C. albicans to the essential oil resulted in impairment of mitochondrial functions in a dose-dependent manner. No difference in ergosterol content was observed in essential oil-treated C. albicans. F. capillaris and α-pinene display a broad fungicidal activity. The fungicidal activity of F. capillaris on C. albicans can be related to an induced oxidative stress which affects enzymes activity and the membrane potential of mitochondria. The essential oil of F. capillaris was shown to have potential for use in the development of clinically useful therapeutic preparations, particularly for topical application in the management of superficial mycoses.

2025, African journal of microbiology research

The pathogenic role of Salmonella infection in the development of human diseases and the impact of resistance on the clinical outcome stimulated the search for newer treatments and natural products that could provide alternative therapies against typhoid fever caused by this intracellular pathogen. Scopoletin has been reported for its anti-inflammatory activity and various other mechanisms underlying intracellular signaling pathways. We aim to determine the in vitro effect of scopoletin in intracellular survival of S. typhi in U937 human macrophage cell line. The LDH releasing assay was used to assess the cytotoxicity of scopoletin and quantified colorimetrically with a CytoTox96 LDH-release kit (Promega, USA). To investigate whether scopoletin affects S. typhi survival within macrophages, U937 cells were incubated with and without scopoletin for various time intervals and measured survival rate counting viable cells. Statistical significance was set at p ˂ 0.05. No cytotoxicity was...

2025, DOAJ (DOAJ: Directory of Open Access Journals)

Background: Candida albicans is a commensal organism that causes a wide variety of diseases in humans. One of these diseases is oral candidiasis, which occurs at a high recurrence rate in spite of available treatments. The purpose of this study was to compare the effect of low-level laser therapy (LLLT) with the use of nystatin on in-vitro growth of Candida albicans. We prepared two samples of Candida albicans at different concentrations: 10 4 viable cells/ml and 10 6 viable cells/ml. Specimens from each sample were divided into a control group, a nystatin-treated group, and a group treated with LLLT. The control group was cultured without any intervention. The second group was treated with nystatin and the solution was vibrated for 30 s or 60 s. The third group was irradiated with a galliumaluminum-argon (Ga-Al-Ar) diode laser (Epic 10; Biolase Inc.)in continuous mode using a wavelength of 940 nm and a power of 1 W for 30 s or 60 s (38 J/cm 2 and 76 J/cm 2 ). The specimens from the nystatin group and the LLLT group were cultured and the number of colony-forming units (CFU/ml) for each group was counted and compared. Results: Nystatin completely eliminated the colonies (0 colonies) in all specimens. There was an increase in the number of colonies in the LLLT group for both cell concentrations at 30 s and at 60 s. However, this increase was statistically significant only for a concentration of 10 4 viable cells/ml at an exposure time of 30s. The increase in the concentration of 10 6 viable cells/ml at both 30 s and 60 s was statistically significant compared with the control group, although the highest number of colonies remained after an exposure time of 60s. Conclusion: LLLT led to an increase in the growth of Candida colonies. However, there was no significant difference related to the exposure time between the different cell concentrations.

2025, Journal of Antimicrobial Chemotherapy

Objectives: Silver carbenes may represent novel, broad-spectrum antimicrobial agents that have low toxicity while providing varying chemistry for targeted applications. Here, the bactericidal activity of four silver carbene complexes (SCCs) with different formulations, including nanoparticles (NPs) and micelles, was tested against a panel of clinical strains of bacteria and fungi that are the causative agents of many skin and soft tissue, respiratory, wound, blood, and nosocomial infections. Methods: MIC, MBC and multidose experiments were conducted against a broad range of bacteria and fungi. Time-release and cytotoxicity studies of the compounds were also carried out. Free SCCs and SCC NPs were tested against a panel of medically important pathogens, including methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Acinetobacter baumannii (MRAB), Pseudomonas aeruginosa, Burkholderia cepacia and Klebsiella pneumoniae. Results: All four SCCs demonstrated strong efficacy in concentration ranges of 0.5 -90 mg/L. Clinical bacterial isolates with high inherent resistance to purified compounds were more effectively treated either with an NP formulation of these compounds or by repeated dosing. Overall, the compounds were active against highly resistant bacterial strains, such as MRSA and MRAB, and were active against the biodefence pathogens Bacillus anthracis and Yersinia pestis. All of the medically important bacterial strains tested play a role in many different infectious diseases. The four SCCs described here, including their development as NP therapies, show great promise for treating a wide variety of bacterial and fungal pathogens that are not easily killed by routine antimicrobial agents.

2025, Journal of photochemistry and photobiology. B, Biology

Multidrug resistant (MDR) bacterial infections have become a severe threat to the community health due to a progressive rise in antibiotic resistance. Nanoparticle-based photodynamic therapy (PDT) is increasingly been adopted as a potential antimicrobial option, yet the cytotoxicity associated with PDT is quite unspecific. Herein, we show Concanavalin-A (ConA) directed dextran capped gold nanoparticles (GNPDEX-ConA) enhanced the efficacy and selectivity of methylene blue (MB) induced killing of multidrug resistant clinical isolates. Here, we show that our complex MB@GNPDEX-ConA is effective against range of MDR clinical isolates, including Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae. In our treatment modality negligible dark toxicity suggests photochemically driven process with 97% killing of MDR bacteria. GNPDEX-ConA with monomeric form of MB departs maximum fluorescence decay time (τf: 1.7ns in HSA) and singlet oxygen (ΔΦ; 0.84) for improved activity in albumi...

2025

It is well recognized that interpretations of Mars must begin with the Earth as a reference. The most successful comparisons have focused on understanding geologic processes on the Earth well enough to extrapolate to Mars' environment. Several facets of terrestrial analog studies have been pursued and are continuing. These studies include field workshops, characterization of terrestrial analog sites, instrument tests, laboratory measurements (including analysis of Martian meteorites), and computer and laboratory modeling. The combination of all these activities allows scientists to constrain the processes operating in specific terrestrial environments and extrapolate how similar processes could affect Mars. The Terrestrial Analogs for Mars Community Panel has considered the following two key questions: (1) How do terrestrial analog studies tie in to the Mars Exploration Payload Assessment Group science questions about life, past climate, and geologic evolution of Mars, and (2) How can future instrumentation be used to address these questions. The panel has considered the issues of data collection, value of field workshops, data archiving, laboratory measurements and modeling, human exploration issues, association with other areas of solar system exploration, and education and public outreach activities.

2025, Applied Microbiology and Biotechnology

The impact of polyunsaturated fatty acid (PUFA) degradation on the survival and acidification activity of freeze-dried Weissella paramesenteroides LC11 was investigated over 90-days storage at 4 °C or 20 °C in vacuumsealed aluminium foil or glass tubes with two water activities (a w =0.11 or 0.23). Colony counts, acidification activity (% lactic acid/g), linoleic/palmitic (18:2/16:0) or linolenic/palmitic (18:3/16:0) ratio by gas chromatography and 18:2 or 18:3 oxylipins by reversed phase-high performance liquid chromatography were determined. The viable cells, acidification activity and 18:2/16:0 or 18:3/ 16:0 ratio decreased as the storage time increased. The survival, acidification activity and 18:2/16:0 or 18:3/16:0 ratio were greatest for the freeze-dried strain held in vacuum-sealed aluminium foil at 4 °C. The 18:2/16:0 or 18:3/16:0 ratio decrease was correlated with the accumulation of 18:2 or 18:3 oxylipins during storage in glass tubes. Hydroperoxy PUFAs, hydroxy PUFAs, divinyl ether PUFAs and oxo PUFAs were the main oxylipins identified. A large decrease in the 18:2/16:0 or 18:3/16:0 ratio and a rapid accumulation of oxylipins during storage might be enough to cause high cell death and loss of metabolic activity. These results provide further experimental support for the hypothesis that lipid oxidation and survival or activity of freeze-dried bacteria might be related.

2025, Antimicrobial Agents and Chemotherapy

We report that both culture and the cell-free culture supernatant (CFCS) of Lactobacillus acidophilus strain LB (Lactéol Boucard) have the ability (i) to delay the appearance of Salmonella enterica serovar Typhimurium strain SL1344-induced mobilization of F-actin and, subsequently, (ii) to retard cell entry by S . Typhimurium SL1344. Time-lapse imaging and Western immunoblotting showed that S . Typhimurium SL1344 swimming motility, as represented by cell tracks of various types, was rapidly but temporarily blocked without affecting the expression of FliC flagellar propeller protein. We show that the product(s) secreted by L. acidophilus LB that supports the inhibitory activity is heat stable and of low molecular weight. The product(s) caused rapid depolarization of the S . Typhimurium SL1344 cytoplasmic membrane without affecting bacterial viability. We identified inhibition of swimming motility as a newly discovered mechanism by which the secreted product(s) of L. acidophilus strai...

2025, Journal of the Science of Food and Agriculture

BACKGROUNDPulsed light (PL) is emerging as a non‐thermal technology with excellent prospects for the decontamination of foods and food contact surfaces. Its application for mould inactivation on cereal grains would allow a reduction of storage losses as well as the prevention of mycotoxin contamination at a post‐harvest level. The potential of PL for the decontamination of naturally occurring moulds on wheat grain was investigated in this study.RESULTSTreatments of up to 40 flashes of a fluence of 0.4 J cm−2 per pulse were applied to both sides of the grain, with an overall energy release ranging from 6.4 to 51.2 J g−1. The most powerful treatment applied to wheat in this study (51.2 J g−1) resulted in a mould reduction of approximately 4 log cycles on samples displaying an initial mould contamination level of 2.2 × 105 CFU g−1. At the same time, the seed germination percentage was only slightly affected. For PL treatments causing an inactivation of 3–4 log cycles, only 14–15% of th...

2025, Frontiers in Cellular and Infection Microbiology

Transporters of the cation diffusion facilitator (CDF) family form dimers that export transition metals from the cytosol. The opportunistic pathogen Pseudomonas aeruginosa encodes three homologous CDF genes, czcD (PA0397), aitP (PA1297), and yiiP (PA3963). The three proteins are required for virulence in a plant host model. Disruption of the aitP gene leads to higher Fe 2+ and Co 2+ sensitivity together with an intracellular accumulation of these ions and to a decreased survival in presence of H 2 O 2 . Strains lacking czcD and yiiP showed low Zn 2+ sensitivity. However, in iron-rich media and in the presence of Zn 2+ these strains secreted higher levels of the iron chelator pyoverdine. Disruption of czcD and yiiP in a non-pyoverdine producer strain and lacking the Zn 2+ -transporting ATPase, increased the Zn 2+ sensitivity and the accumulation of this ion. Most importantly, independent of the pyoverdine production strains lacking CzcD or YiiP, presented lower resistance to imipenem, ciprofloxacin, chloramphenicol, and gentamicin. These observations correlated with a lower survival rate upon EDTA-lysozyme treatment and overexpression of OprN and OprD porins. We hypothesize that while AitP is an Fe 2+ /Co 2+ efflux transporter required for Fe 2+ homeostasis, and ultimately redox stress handling, CzcD, and YiiP export Zn 2+ to the periplasm for proper Zn 2+ -dependent signaling regulating outer membrane stability and therefore antibiotic tolerance.

2025, Infection and Immunity

Nontypeable Haemophilus influenzae (NTHI) is a Gram-negative bacterial pathogen that causes upper and lower respiratory infections. Factors required for pulmonary infection by NTHI are not well understood. Previously, using high-throughput insertion tracking by deep sequencing (HITS), putative lung colonization factors were identified. Also, previous research indicates that secreted disulfide-dependent factors are important for virulence of H. influenzae. In the present study, HITS data were compared with an informatics-based list of putative substrates of the periplasmic oxidoreductase DsbA to find and characterize secreted virulence factors. This analysis resulted in identification of the "zinc binding essential for virulence" (zev) locus consisting of zevA (HI1249) and zevB (HI1248). NTHI mutants of zevA and zevB grew normally in rich medium but were defective for colonization in a mouse lung model. Mutants also exhibited severe growth defects in medium containing EDTA and were rescued by supplementation with zinc. Additionally, purified recombinant ZevA was found to bind to zinc with high affinity. Together, these data demonstrate that zevAB is a novel virulence factor important for zinc utilization of H. influenzae under conditions where zinc is limiting. Furthermore, evidence presented here suggests that zinc limitation is likely an important mechanism for host defense against pathogens during lung infection.

2025, Infection and Immunity

Salmonella serovars contain a wide variety of putative fimbrial systems that may contribute to colonization of specific niches. Salmonella enterica serovar Typhi is the etiologic agent of typhoid fever and is a pathogen specific to humans. In a previous study, we identified a gene, STY3920 ( stgC ), encoding the predicted usher of the stg fimbrial operon, that was expressed by serovar Typhi during infection of human macrophages. The stg genes are located in the glmS - pstS intergenic region in serovar Typhi and certain Escherichia coli strains, but they are absent in other S. enterica serovars. We cloned the stg fimbrial operon into a nonfimbriate E. coli K-12 strain and into S. enterica serovar Typhimurium. We demonstrated that the stg fimbrial operon contributed to increased adherence to human epithelial cells. Transcriptional fusion assays with serovar Typhi suggested that stg is preferentially expressed in minimal medium. Deletion of stg reduced adherence of serovar Typhi to epi...

2025, Vaccine

Neonates have a poorly developed immune system. Therefore it is important to develop vaccination strategies that induce protective immunity and immunological memory against pathogens early in life. The immunogenicity of a meningococcal serogroup C polysaccharide conjugate (MenC-CRM 197 ) was assessed in neonatal mice, and effects of LT-K63 and CpG2006 and immunisation routes were compared. Neonatal mice were primed subcutaneously (s.c.) or intranasally (i.n.) with MenC-CRM 197 with or without LT-K63 or CpG2006 and re-immunised 16 and 30 days later by the same route and formulation. Antibody levels were measured and generation of immunological memory assessed by affinity maturation and kinetics of the Ab response. Serum bactericidal activity (SBA) was measured to evaluate protective efficacy. The second and third dose of MenC-CRM 197 mixed with either LT-K63 or CpG2006 induced a rapid increase in MenC-specific IgG antibodies, to levels higher than elicited by MenC-CRM 197 alone (P < 0.01) and in unimmunised mice (P < 0.001), indicating efficient generation of memory by priming through both s.c. and i.n. routes. SBA was detected after three s.c. immunisations with MenC-CRM 197 s.c. alone. However, only two doses of MenC-CRM 197 +LT-K63 or MenC-CRM 197 +CpG2006 were needed to induce SBA levels > 16. LT-K63 and CpG2006 enhanced neonatal antibody responses, affinity maturation, immunological memory to the conjugate MenC-CRM 197 and protective immunity. These results encourage the development of neonatal vaccination strategies to induce protective immunity and immunological memory against meningococcal disease.

2025, Vaccine

2025, Lasers in Medical Science

In prior studies, exposure of Streptococcus mutans in biofilm to blue light using high fluences of up to 680 J/cm 2 did not interfere with bacterial capability to reform an initial biofilm; however, a delayed antibacterial effect was observed. Our aim was to determine the sustained effecttts of blue lightemitting diode (LED) curing light on the pathogenicity of the newly formed biofilm. S. mutans were grown to form biofilm that was exposed to blue light (wavelengths, 460-480 nm) for 1, 3, and 7 min (equivalent to 37, 112, and 262 J/cm 2 , respectively). Then, bacteria were suspended and allowed to regrow into new biofilms. The regrown biofilms were assessed for bacterial quantification by optical density (OD) measurement and quantitative polymerase chain reaction (qPCR), bacterial viability and extracellular polysaccharide production by fluorescent staining using confocal scanning laser microscopy, acid production by bacteria (acidogenicity), and bacterial survival at low pH (aciduricity) using qPCR. Bacterial growth in the regrown biofilms was increased when samples were previously exposed to light; however, under the confocal microscopy, a higher proportion of dead bacteria and a reduction in polysaccharide production were observed. The acidogenicity from the regrown biofilm was lowered as fluences of light increased. The aciduricity of the regrown biofilm was decreased, meaning less growth of bacteria into biofilm in low pH with increasing fluences. Blue light has sustained effects on S. mutans bacteria grown into new biofilm. Although bacterial growth in biofilm increased, bacterial viability and virulence characteristics were impaired. The cariogenic potential over time of S. mutans previously exposed to blue light when grown on tooth surfaces is yet to be determined.

2025, Chemical engineering transactions

Actually, functional fermented milks have to exhibit multiple benefits for the health, associated to good organoleptic characteristics. These are strengthened by the addition of probiotics as well as certain soluble fibers, among which inulin. The aim of this work was the evaluation of the effect of inulin supplementation of milk basis on the production of probiotic fiber-enriched fermented milks. To this purpose, we investigated the kinetics of acidification of inulin supplementation of milk (0, 1, 2 and 4 g/100 g) throughout the fermentation, the probiotic survival, the post-acidification and the firmness of fermented fiber-enriched milks, stored at 4°C either for 24 h or after 7 days since their preparation. This work shows that the biomilk preparation is influenced either by the supplemented amount of inulin or by the co-culture composition. According to the selected co-culture, inulin addition to the milk influenced the kinetic parameters of acidification, the concentration of probiotics, the post-acidification and the firmness of fermented fiber-enriched milk.

2025, Brazilian Journal of Microbiology

This study evaluated the effects of prebiotics on fermentation profile and growth of Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus rhamnosus, and Bifidobacterium lactis in co-cultures with Streptococcus thermophilus. Acidification rate and viability were positively influenced by the co-culture with B. lactis and by both inulin or oligofructose in low fat milk.

2025, Journal of Food Science

Campylobacter jejuni is the leading cause of bacterial diarrheal illness worldwide. Many strains are now becoming multidrug resistant. Apple-based edible films containing carvacrol and cinnamaldehyde were evaluated for bactericidal activity against antibiotic resistant and susceptible C. jejuni strains on chicken. Retail chicken breast samples inoculated with D28a and H2a (resistant strains) and A24a (a sensitive strain) were wrapped in apple films containing cinnamaldehyde or carvacrol at 0.5%, 1.5%, and 3% concentrations, and then incubated at 4 or 23 • C for 72 h. Immediately after wrapping and at 72 h, samples were plated for enumeration of viable C. jejuni. The antimicrobial films exhibited dose-and temperaturedependent bactericidal activity against all strains. Films with ≥1.5% cinnamaldehyde reduced populations of all strains to below detection at 23 • C at 72 h. At 4 • C with cinnamaldehyde, reductions were variable for all strains, ranging from 0.2 to 2.5 logs and 1.8 to 6.0 logs at 1.5% and 3.0%, respectively. Films with 3% carvacrol reduced populations of A24a and H2a to below detection, and D28a by 2.4 logs at 23 • C and 72 h. A 0.5-log reduction was observed for both A24a and D28a, and 0.9 logs for H2a at 4 • C at 3% carvacrol. Reductions ranged from 1.1 to 1.9 logs and 0.4 to 1.2 logs with 1.5% and 0.5% carvacrol at 23 • C, respectively. The films with cinnamaldehyde were more effective than carvacrol films. Reductions at 23 • C were greater than those at 4 • C. Our results showed that antimicrobial apple films have the potential to reduce C. jejuni on chicken and therefore, the risk of campylobacteriosis. Possible mechanisms of antimicrobial effects are discussed.

2025, International Journal of Food Microbiology

There is generally no kill-step when preparing salad vegetables, so there is a greater risk for foodborne illness from contaminated vegetables. Some essential oils have antimicrobial activities and could provide a natural way to reduce pathogens on fresh produce. The objective of this study was to investigate the antimicrobial activity of cinnamon oil wash against Salmonella enterica serotype Newport on organic leafy greens. Organic romaine and iceberg lettuce, and organic baby and mature spinach were inoculated with Salmonella Newport and then dip treated in a phosphate buffered saline (PBS) control and 3 different concentrations (0.1, 0.3, and 0.5% v/v) of cinnamon oil. The treatment time varied at either 1 or 2 min, and storage temperature varied at either 4 or 8 °C. Samples were collected at days 0, 1, and 3. For romaine and iceberg lettuce, S. Newport was not recovered on day 3 for 2 min 0.3% and 0.5% cinnamon oil treatments. For mature spinach, S. Newport was not recovered by day 3 for the 2 min 0.3% and 0.5% 4 °C treatments. For baby spinach, there was no recovery of S. Newport by day 1 for all 0.5% treatments. Overall, the cinnamon oil treatments were concentration and time dependent with higher concentrations and longer treatment times providing the greatest reduction in S. Newport population on leafy greens. In addition, the treatments had a residual effect with the greatest reduction generally seen on the last day of sampling. Storage temperature did not have a significant effect on the reduction of S. Newport. Based on the results of this study, cinnamon oil has the potential to be used as a treatment option for washing organic baby and mature spinach, and iceberg and romaine lettuces.

2025, Brazilian Journal of Microbiology

The purpose of this study was to determine the effect of bacteriophage P100 on strains of Listeria monocytogenes in artificially inoculated soft cheeses. A mix of L. monocytogenes 1/2a and Scott A was inoculated in Minas Frescal and Coalho cheeses (approximately 10 5 cfu/g) with the bacteriophage added thereafter (8.3 x 10 7 PFU/g). Samples were analyzed immediately, and then stored at 10 °C for seven days. At time zero, 30 min post-infection, the bacteriophage P100 reduced L. monocytogenes counts by 2.3 log units in Minas Frescal cheese and by 2.1 log units in Coalho cheese, compared to controls without bacteriophage. However, in samples stored under refrigeration for seven days, the bacteriophage P100 was only weakly antilisterial, with the lowest decimal reduction (DR) for the cheeses: 1.0 log unit for Minas Frescal and 0.8 log units for Coalho cheese. The treatment produced a statistically significant decrease in the counts of viable cells (p < 0.05) and in all assays performed, we observed an increase of approximately one log cycle in the number of viable cells of L. monocytogenes in the samples under refrigeration for seven days. Moreover, a smaller effect of phages was observed. These results, along with other published data, indicate that the effectiveness of the phage treatment depends on the initial concentration of L. monocytogenes, and that a high concentration of phages per unit area is required to ensure sustained inactivation of target pathogens on food surfaces.

2025, HAL (Le Centre pour la Communication Scientifique Directe)

2025, 43rd COSPAR Scientific Assembly. Held 28 January - 4 February

2025

During the project MASE (Mars Analogues for Space Exploration) several isolates were obtained and these strains were subjected to Mars relevant environmental stress factors in the laboratory under controlled conditions; e.g. radiation, low water activity, high salt concentrations, oxidizing compounds. First screening steps were always the microorganisms’ tolerance to survive times of desiccation and exposure to ionizing radiation. Both treatments were performed under anoxic conditions.

2025

Five (facultative) anaerobic strains, namely Buttiauxella sp. MASE-IM-9, Clostridium sp. MASE-IM-4, Halanaerobium sp. MASE-BB-1, Trichococcus sp. MASE-IM-5, and Yersinia intermedia MASE-LG-1 from different extreme terrestrial environments were subjected to Mars relevant environmental stress factors (low water activity, oxidizing compounds, ionizing radiation) in the laboratory under controlled anoxic conditions. The survival after addition of sodium perchlorate at different concentrations for dedicated time points was species specific. The inter comparison of the five microorganisms revealed that Clostridium sp. MASE-IM-4 was the most sensitive strain (D10-value = 0.6 M). The most tolerant microorganism was Trichococcus sp. MASE-IM-5 with a D10-value around 1.9 M after fifteen minutes treatment with sodium perchlorate. In parallel, the cultivation and growth of the strains in the presence of sodium perchlorate in Martian relevant concentrations (0.5 % / 1 % wt/vol) led mostly to agg...

2025, Nature communications

The public health threat posed by a looming 'post-antibiotic' era necessitates new approaches to antibiotic discovery. Drug development has typically avoided exploitation of membrane-binding properties, in contrast to nature's control of biological pathways via modulation of membrane-associated proteins and membrane lipid composition. Here, we describe the rejuvenation of the glycopeptide antibiotic vancomycin via selective targeting of bacterial membranes. Peptide libraries based on positively charged electrostatic effector sequences are ligated to N-terminal lipophilic membrane-insertive elements and then conjugated to vancomycin. These modified lipoglycopeptides, the 'vancapticins', possess enhanced membrane affinity and activity against methicillin-resistant Staphylococcus aureus (MRSA) and other Gram-positive bacteria, and retain activity against glycopeptide-resistant strains. Optimised antibiotics show in vivo efficacy in multiple models of bacterial infec...

2025, BMC Microbiology

Background: Globally, staphylococci have developed resistance to many antibiotics. New approaches to chemotherapy are needed and one such approach could be to use plant derived actives with conventional antibiotics in a synergestic way. The purpose of this study was to isolate α-mangostin from the mangosteen (Garcinia mangostana L.; GML) and investigate antibacterial activity and mechanisms of action when used singly and when combined with oxacillin against oxacillin-resistant Staphylococcus saprophyticus (ORSS) strains. The isolated α-mangostin was confirmed by HPLC chromatogram and NMR spectroscopy. The minimum inhibitory concentration (MIC), checkerboard and killing curve were determined. The modes of action of these compounds were also investigated by enzyme assay, transmission electron microscopy (TEM), confocal microscopic images, and cytoplasmic membrane (CM) permeabilization studies. Results: The MICs of isolated α-mangostin and oxacillin against these strains were 8 and 128 μg/ml, respectively. Checkerboard assays showed the synergistic activity of isolated α-mangostin (2 μg/ml) plus oxacillin (16 μg/ml) at a fractional inhibitory concentration index (FICI) of 0.37. The kill curve assay confirmed that the viability of oxacillin-resistant Staphylococcus saprophyticus DMST 27055 (ORSS-27055) was dramatically reduced after exposure to isolated α-mangostin (2 μg/ml) plus oxacillin (16 μg/ml). Enzyme assays demonstrated that isolated α-mangostin had an inhibitory activity against β-lactamase in a dose-dependent manner. TEM results clearly showed that these ORSS-27055 cells treated with this combination caused peptidoglycan and cytoplasmic membrane damage, irregular cell shapes and average cell areas were significantly larger than the control. Clearly, confocal microscopic images confirmed that this combination caused considerable peptidoglycan damage and DNA leakage. In addition, the CM permeability of ORSS-27055 was also increased by this combination of actives.

2025, Journal of photochemistry and photobiology. B, Biology

2025, Journal of Basic Microbiology

The antibacterial effect of AgNPs was investigated by determining MIC/MBC and growth kinetics assay. The lowest MIC/MBC was found to be in the range of 11.25–22.5 µg ml−1. The growth kinetics curve shows that 25 µg ml−1 AgNPs strongly inhibits the bacterial growth. Confocal laser scanning electron microscopy (CLSM) shows that as the concentration of NPs increases, reduction in the number of cells was observed and at 50 µg ml−1 of NPs, 100% death was noticed. Scanning electron microscopy (SEM) shows cells were severely damaged with pits, multiple depressions, and indentation on cell surface and original rod shape has swollen into bigger size. High resolution‐transmission electron microscopic (HR‐TEM) micrograph shows that cells were severely ruptured. The damaged cells showed either localized or complete separation of the cell membrane. The NPs that anchor onto cell surface and penetrating the cells may cause membrane damage, which could result in cell lysis. The interaction of AgNPs...

2025, PLoS ONE

The effect of temperature fluctuation is an important factor in bacterial growth especially for pathogens such as the staphylococci that have to remain viable during potentially harsh and prolonged transfer conditions between hosts. The aim of this study was to investigate the response of S. aureus, S. epidermidis, and S. lugdunensis when exposed to low temperature (4uC) for prolonged periods, and how this factor affected their subsequent growth, colony morphology, cellular ultra-structure, and amino acid composition in the non-cytoplasmic hydrolysate fraction. Clinical isolates were grown under optimal conditions and then subjected to 4uC conditions for a period of 8 wks. Cold-stressed and reference control samples were assessed under transmission electron microscopy (TEM) to identify potential ultra-structural changes. To determine changes in amino acid composition, cells were fractured to remove the lipid and cytoplasmic components and the remaining structural components were hydrolysed. Amino acid profiles for the hydrolysis fraction were then analysed for changes by using principal component analysis (PCA). Exposure of the three staphylococci to prolonged low temperature stress resulted in the formation of increasing proportions of small colony variant (SCV) phenotypes. TEM revealed that SCV cells had significantly thicker and more diffuse cell-walls than their corresponding WT samples for both S. aureus and S. epidermidis, but the changes were not significant for S. lugdunensis. Substantial species-specific alterations in the amino acid composition of the structural hydrolysate fraction were also observed in the cold-treated cells. The data indicated that the staphylococci responded over prolonged periods of cold-stress treatment by transforming into SCV populations. The observed ultra-structural and amino acid changes were proposed to represent response mechanisms for staphylococcal survival amidst hostile conditions, thus maintaining the viability of the species until favourable conditions arise again.

2025, avinik publication

The present study was characterized for antioxidant potential of the skin ethanolic extracts of Uroteuthis sibogae. The free radical scavenging properties was analysed by (DPPH), ABTS, Reducing power (RP), inhibition of β-carotene bleaching assay and total antioxidant capacity (TAC) at concentrations ranging from 2 to 10 mg/ml. The inhibition was compared with respective synthetic antioxidants. Free radical scavenging at the highest concentration inhibition yield for DPPH was 79.34%, ABTS 90.44 %, RP 91.20%, β-carotene assay was 155.67% and TAC 95.54% was reported. The results from the present study will be helpful to develop nutraceutical supplements obtained from discard of squid which can be used as natural antioxidant to retard the lipid oxidation. This would provide pharmacophore leads from molluscan species in combating free radical chain formation and being a source of target for degenerative and life style modified disease management.

2025, Applied and Environmental Microbiology

A microtiter alamarBlue assay was adapted and optimized for Mycobacterium avium subsp. paratuberculosis . Using cell concentrations ranging from 10 4 to 10 8 CFU/ml, a minimum incubation time to indicate viability was obtained after 24 h. Rifampin (rifampicin) was used to demonstrate that this method has applications for high-throughput screening against M. avium subsp. paratuberculosis .

2025, Applied microbiology and biotechnology

Enterococcus faecalis is a commensal bacterium of the human gut that requires the ability to pass through the stomach and therefore cope with low pH. E. faecalis has also been identified as one of the major tyramine producers in fermented food products, where they also encounter acidic environments. In the present work, we have constructed a non-tyramine-producing mutant to study the role of the tyramine biosynthetic pathway, which converts tyrosine to tyramine via amino acid decarboxylation. Wild-type strain showed higher survival in a system that mimics gastrointestinal stress, indicating that the tyramine biosynthetic pathway has a role in acid resistance. Transcriptional analyses of the E. faecalis V583 tyrosine decarboxylase cluster showed that an acidic pH, together with substrate availability, induces its expression and therefore the production of tyramine. The protective role of the tyramine pathway under acidic conditions appears to be exerted through the maintenance of the...

2025

S. agalactiae infection is one of the most important bacterial diseases imparting mass mortality in the aquaculture sector, worldwide. It is responsible for posing both economic burdens and risks of cross-infectivity and zoonotic transmission. In this aspect, this study examined the virulence gene profiles, molecular serotyping and pathogenicity of S. agalactiae strains isolated from tilapia farms in Kerala, India in 2022. Following sample collection and processing, three S. agalactiae strains (KSA/01, KSA/02, and KSA/03) were isolated and confirmed the bacterial identity using 16S rRNA sequencing. In pathogenicity test, the LD 50 of the S. agalactiae was found to be 1 × 10 6 CFU/ml. An increase in the salinity was found to affect the pathogenicity of S. agalactiae as well as the hematological and serological profile of tilapia. Thus the presence of S. agalactiae, a highly virulent and zoonotic pathogen in tilapia farms, underscores the imperative of continuous monitoring in aquaculture facilities.

2025, The Journal of antimicrobial chemotherapy

Biofilm infections of intravascular catheters caused by Staphylococcus aureus may be treated with catheter lock solutions (CLSs). Here we investigated the antibacterial activity, cytotoxicity and CLS potential of 5-hydroxyethyl-3-tetradecanoyltetramic acid (5HE-C14-TMA) compared with the related compounds 3-tetradecanoyltetronic (C14-TOA) and 3-tetradecanoylthiotetronic (C14-TTA), which are variants of quorum sensing signalling molecules produced by Pseudomonas aeruginosa METHODS: Antibacterial activity and mechanism of action of 5HE-C14-TMA, C14-TOA and C14-TTA were determined via MIC, bacterial killing, membrane potential and permeability assays. Susceptibility of S. aureus biofilms formed in the presence of plasma in vitro was investigated, MTT cytotoxicity testing was undertaken and cytokine release in human blood upon exposure to 5HE-C14-TMA and/or S. aureus biofilms was quantified. The effectiveness of 5HE-C14-TMA as CLS therapy in vivo was assessed using a rat intravascular c...

2025, PloS one

In this manuscript, we describe the identification of highly pathogenic bacteria using an assay coupling biothreat group-specific PCR with electrospray ionization mass spectrometry (PCR/ESI-MS) run on an Ibis PLEX-ID high-throughput platform. The biothreat cluster assay identifies most of the potential bioterrorism-relevant microorganisms including Bacillus anthracis, Francisella tularensis, Yersinia pestis, Burkholderia mallei and pseudomallei, Brucella species, and Coxiella burnetii. DNA from 45 different reference materials with different formulations and different concentrations were chosen and sent to a service screening laboratory that uses the PCR/ESI-MS platform to provide a microbial identification service. The standard reference materials were produced out of a repository built up in the framework of the EU funded project "Establishment of Quality Assurances for Detection of Highly Pathogenic Bacteria of Potential Bioterrorism Risk" (EQADeBa). All samples were co...

2025, Colloids and Surfaces B: Biointerfaces

The potential use of non-viable biomass of a Gram negative bacterium i.e. Acinetobacter haemolyticus to remove Cr(III) species from aqueous environment was investigated. Highest Cr(III) removal of 198.80 mg g -1 was obtained at pH 5, biomass dosage of 15 mg cell dry weight, initial Cr(III) of 100 mg L -1 and 30 min of contact time. The Langmuir and Freundlich models fit the experimental data (R 2 > 0.95) while the kinetic data was best described using the pseudo second-order kinetic model (R 2 > 0.99). Cr(III) was successfully recovered from the bacterial biomass using either 1 M of CH 3 COOH, HNO 3 or H 2 SO 4 with 90% recovery. TEM and FTIR suggested the involvement of amine, carboxyl, hydroxyl and phosphate groups during the biosorption of Cr(III) onto the cell surface of A. haemolyticus. A. haemolyticus was also capable to remove 79.87 mg g -1 Cr(III) (around 22.75%) from raw leather tanning wastewater. This study demonstrates the potential of using A. haemolyticus as biosorbent to remove Cr(III) from both synthetic and industrial wastewater.

2025, Nature communications

2025, 10-بهار1404

Nowadays the discussion of research in the field of medicinal and food plants is important, and expanding the range of new drugs from natural sources as a suitable solution with strategic and economic value has become particularly important. One of these suitable and practical plants is mint (Mentha spicata L) and has many medicinal properties. 2.4 mL of mint essential oil was obtained by extracting the essential oil with a Clevenger device. In order to optimize the storage conditions, the extracted essential oil was stored under four different storage conditions: (1) open door of the chamber at ambient temperature (2) Closed compartment door at ambient temperature (3) Open compartment door at refrigerator temperature (4) Closed compartment door was placed at refrigerator temperature. COMSOL Multiphysics software was used with the aim of following the simulation of different storage conditions of the extracted essential oil. By simulating the mass transfer process under different storage conditions, the initial time of essential oil evaporation for 4 conditions in the storage conditions (1), (2), (3) and (4) were 30, 105, respectively. 270 and 480 min were obtained. In other words, after the calculated times, the volume reduction will occur in the extracted essential oil. The antioxidant property of mint essential oil was measured by the DPPH method and the value was 56%. After 144 hours of storage time, the antioxidant property of the samples with different conditions (1) to (4) reached the values of 7%, 18%, 13% and 47%, respectively. The results of the antibacterial properties of min essential oil against two different gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacterial species were evaluated and the antibacterial properties of the essential oil against gram-positive bacteria (22 mm) were higher than gram-negative bacteria (17 mm). The evaluation of the antibacterial property of the essential oil under 4 different conditions with 144 hours passed, the best maintenance condition was condition (4) in which against gram positive bacteria, a reduction of 13% equivalent to 19 mm and against gram negative bacteria with a reduction of 11% property, halo diameter Formed 15 mm was obtained.

2025, Nature cell biology

Anaphase chromatin bridges can lead to chromosome breakage if not properly resolved before completion of cytokinesis. The NoCut checkpoint, which depends on Aurora B at the spindle midzone, delays abscission in response to chromosome segregation defects in yeast and animal cells. How chromatin bridges are detected, and whether abscission inhibition prevents their damage, remain key unresolved questions. We find that bridges induced by DNA replication stress and by condensation or decatenation defects, but not dicentric chromosomes, delay abscission in a NoCut-dependent manner. Decatenation and condensation defects lead to spindle stabilization during cytokinesis, allowing bridge detection by Aurora B. NoCut does not prevent DNA damage following condensin or topoisomerase II inactivation; however, it protects anaphase bridges and promotes cellular viability after replication stress. Therefore, the molecular origin of chromatin bridges is critical for activation of NoCut, which plays ...

2025, Molecular & cellular proteomics : MCP

Enterohaemorrhagic Escherichia coli is a leading cause of foodborne illness, with the majority of cases linked to foods of bovine origin. Currently, no completely effective method for controlling this pathogen during carcass processing exists. Understanding how this pathogen behaves under those stress conditions experienced on the carcass during chilling in cold air could offer opportunities for development or improvement of effective decontamination processes. Therefore, we studied the growth kinetics and physiological response of exponential phase E. coli O157:H7 Sakai cultures upon an abrupt downshift in temperature and water activity (from 35°C aw 0.993 to 14°C aw 0.967). A parallel Biolog study was conducted to follow the phenotypic responses to 190 carbon sources. Exposure of E. coli to combined cold and water activity stresses resulted in a complex pattern of population changes. This pattern could be divided into two main phases, including adaptation and re-growth phases, bas...