Bacterial Biofilms Research Papers - Academia.edu (original) (raw)

This paper presents a new NDT technique based on bacterial cell suspensions to identify surface micro defects in a procedure similar to the one used in dye penetrant. Validation was performed using Rhodococcus erythropolis bacteria in aluminum, steel and copper samples, studying the penetration, liquid removal and revelation stages and the phenomena involved in each one, as well as, bacteria/material interaction. A detectability limit was estimated and this was seen to depend on the material. Under the tested conditions defects with a depth of 4.3, 2.9 and 6.8 µm were identified in Al, steel and Cu, respectively.

- by and +1
- •
- Engineering, Nondestructive Testing, Inspection and Evaluation (NDT/NDE), Magnetic particles, Bacteria

Civil engineers have a responsibility to take measures to protect marine biodiversity by selecting more bioreceptive construction materials in the design of marine infrastructure, for better biodiversity conservation. In this study, it was shown that pre-carbonation of cementitious materials accelerates their bacterial colorization by lowering the pH of their surface. It has been shown both in the laboratory and in-situ tests that the bacterial colonization of cementitious materials is influenced by the pH and the type of cement. By comparing the bacterial colonization of Portland cement mortars, CEM I, and slag cement, CEM III, mortars, it was found that the CEM III mortars are more bioreceptive than the CEM I mortars. This study presented and verified a novel experimental laboratory approach which can be used to evaluate the bacterial colonization (bioreceptivity) of cementitious materials in marine environment. The approach could be taken up in future recommendations to enable engineers to eco-design more eco-friendly marine infrastructure and develop green-engineering projects.

- by MAHMOUD HAYEK and +2
- •
- Marine Ecology, Bacterial Biofilms, Marine Biofouling, Cement and Concrete Materials

The arginine-specific aminopeptidase autotransporter of Pseudomonas aeruginosa (AaaA) is an important virulence factor, conferring a fitness advantage in environments where the sole source of nitrogen and carbon is aminoterminal arginine peptides; more specifically, the cleaving of arginine from the arg-gly-asp tripeptide. Pseudomonas aeruginosa can utilise arginine through various pathways engendering growth, increased metabolic activity, and adaption in hostile environments. Such adaptions include the formation of biofilms which can increase antibiotic tolerance and resistance to the host immune defence. AaaA is tethered to the outer membrane by its embedded beta-barrel which highlights it as a potentially viable target for chemotherapeutic agents; before that is practicable, further understanding is required of the complex regulatory network that encompasses it. Employment of peg-lid assays and confocal microscopy demonstrated that exogenous arginine increased biofilm growth; these biofilms were characteristically thicker and more developed. Addition of the tripeptide to biofilm assays showed that AaaA was unable to cleave the aminoterminal arginine, at least in that context. Through the use of transcriptional reporters, and luminescence assays, negative regulation of the aaaA promoter was demonstrated by AaaA whereas SpeA, which decarboxylates arginine to agmatine in the arginine decarboxylase pathway, showed positive regulation. To enhance understanding of known regulators, site-directed mutagenesis was implemented to engineer changes in RpoN (RNA polymerase sigma-54 factor) and IHF (Integration host factor) binding motifs on the aaaA promoter region. In summary, arginine is crucial in the formation of biofilms in Pseudomonas aeruginosa; however, the multifaceted regulation and function of AaaA is still being deciphered.

- by Jack Kiney Whitmore
- •
- Biofilms, Protein Secretion, Microbial biofilms, Pseudomonas aeruginosa

Staphylococcus aureus and Pseudomonas aeruginosa are bacteria that cause biofilm-associated infections. The aim of this study was to determine the activity of combined betacyanin fractions from Amaranthus dubius (red spinach) and Hylocereus polyrhizus (red pitahaya) against biofilms formed by co-culture of S. aureus and P. aeruginosa on different polymer surfaces. Various formulations containing different concentrations of the betacyanin fractions were investigated for biofilm-inhibiting activity on polystyrene surfaces using crystal violet assay and scanning electron microscopy. A
combination of each betacyanin fraction (0.625 mg mL−1) reduced biofilm formation of five S. aureus strains and four P. aeruginosa strains from optical density values of 1.24–3.84 and 1.25–3.52 to 0.81–2.63 and 0.80–1.71, respectively. These combined fractions also significantly inhibited dual-species biofilms by 2.30 and reduced 1.0–1.3 log CFU cm−2 bacterial attachment on polymer surfaces such as polyvinyl chloride, polyethylene, polypropylene and silicone rubber. This study
demonstrated an increase in biofilm-inhibiting activity against biofilms formed by two species using combined fractions than that by using single fractions. Betacyanins found in different plants could collectively be used to potentially decrease the risk of biofilm-associated infections caused by these bacteria on hydrophobic polymers.

Microbial fuel cells (MFCs) are recognized as a future technology with a unique ability to exploit metabolic activities of living microorganisms for simultaneous conversion of chemical energy into electrical energy. This technology holds the promise to offer sustained innovations and continuous development towards many different applications and value-added production that extends beyond electricity generation, such as water desalination, wastewater treatment, heavy metal removal, bio-hydrogen production, volatile fatty acid production and biosensors. Despite these advantages, MFCs still face technical challenges in terms of low power and current density, limiting their use to powering only small-scale devices. Description of some of these challenges and their proposed solutions is demanded if MFCs are applied on a large or commercial scale. On the other hand, the slow oxygen reduction process (ORR) in the cathodic compartment is a major roadblock in the commercialization of fuel cells for energy conversion. Thus, the scope of this review article addresses the main technical challenges of MFC operation and provides different practical approaches based on different attempts reported over the years.

- by Ola Gomaa and +2
- •
- Bioelectrochemistry, Biofilms, Synthesis of nanoparticles, Biotechnology

Bacterial populations inhabiting pharmaceutical grade water systems were investigated over a fifteen year period. The systems analyzed were mains water, purified and Water-for-Injection (WFI). Samples of water were tested by membrane filtration and the samples cultured using R2A agar. Culture based methods and phenotypic identification methods were used to characterize the isolates. The research was undertaken to produce an in-depth study of the microbiota of pharmaceutical grade water systems. The results presented act as a benchmark for industrial and pharmaceutical microbiologists to review comparable systems against, as well as to present a review of the typical culturable microorganisms recoverable from pharmaceutical water systems.

- by Tim Sandle
- •
- Microbiology, Biofilms, Water, Water quality

The most commonly used packaging material is associated with environmental issues as they are non-degradable in nature. The number of attempts are made for developing the eco-friendly degradable biopolymers as ideal food packaging. The biopolymers developed are not commercialized as they have poor mechanical strength and resistance properties. Thus to enhance the following faults in the reinforcing material are added which resulted in the composites formation. During various food processing operations the nanotechnology approach is employed such as encapsulation of the material in the nanoparticles, which can be delivered to the targeted site, enhancement of the flavor, integration of antibacterial agents with the nanoparticle in the food, enhancement of shelf-life for storage, and contamination sensing. Food packaging substances synthesized by nanotechnology may increase the shelf-life of the food as they provide resistive packaging, increase the level of food safety, liberate the preservatives for enhancing the life of the food and notify the consumer either the food is consumable or spoiled. Nano-supplements are integrated by the encapsulation method for efficient dietary as well as drug delivery systems. Nano-materials are not well evaluated for the health risk and environmental issues associated with it even the side-effects are unexploited. Various authorities are working prompt designing of guidelines and legislation policies for further acceptance of Nano-based materials in food packaging systems. Biologically synthesized nanoparticles will serve as a significant tool to conquer present contests that are linked with food packaging constituents.

- by Daljeet Singh
- •
- Biofilms, Nanotechnology, Food Packaging, Bacterial Biofilms
- by Mohammad Rifky
- •
- Microbiology, Pathology, Zoology, Health Sciences

Biofilms are communities of aggregated bacterial cells embedded in a self-produced extracellular polymeric matrix. Biofilms are recalcitrant to antibiotic treatment and immune defenses and are implicated in many chronic bacterial and fungal infections. In this review, we provide an overview of the contribution of biofilms to persistent infections resistant to antibiotic treatment, the impact of multispecies biofilms on drug resistance and tolerance, and recent advances in the development of antibiofilm agents. Understanding the mechanisms of antibiotic resistance and tolerance in biofilms is essential for developing new preventive and therapeutic strategies and curbing drug resistance.

- by S. Hathroubi
- •
- Microbiology, Biofilms, Veterinary Microbiology, Bacteriology

In Canada, increases in rural development has led to a growing need to effectively manage the resulting municipal and city sewage without the addition of significant cost- and energy- expending infrastructure. Storring Septic Service Limited is a family-owned, licensed wastewater treatment facility located in eastern Ontario. It makes use of a passive waste stabilization pond system to treat and dispose of waste and wastewater in an environmentally responsible manner. Storring Septic, like many other similar small-scale wastewater treatment facilities across Canada, has the potential to act as a sustainable eco-engineered facility that municipalities and service providers could utilize to manage and dispose of their wastewater. However, it is of concern that the substantial inclusion of third party material could be detrimental to the stability and robustness of the pond system. In order to augment the capacity of the current facility, and ensure it remains a self-sustaining system with the capacity to safely accept septage from other sewage haulers, it was hypothesized that pond effluent treatment could be further enhanced through the incorporation of one of three different technology solutions, which would allow the reduction of wastewater quality parameters below existing regulatory effluent discharge limits put in place by Ontario’s Ministry of the Environment and Climate Change (MOECC). Two of these solutions make use of biofilm technologies in order to enhance the removal of wastewater parameters of interest, and the third utilizes the natural water filtration capabilities of zebra mussels. Pilot-scale testing investigated the effects of each of these technologies on treatment performance under both cold and warm weather operation. This research aimed to understand the important mechanisms behind biological filtration methods in order to choose and optimize the best treatment strategy for full-scale testing and implementation. In doing so, a recommendation matrix was developed with the potential to be used as a universal operational strategy for wastewater treatment facilities located in environments of similar climate and ecology.

Development of advanced materials with a benign environmentally friendly approach for heterogeneous visible light photocatalysis is always preferable. An environmentally favorable approach was used to anchor silver nanoparticles (Ag NPs) to tin oxide-decorated-graphitic carbon nitride (SnO2-g-C3N4) using a biofilm as a green reducing tool for the biogenic synthesis of 1–6 mM Ag@SnO2-g-C3N4 nanostructures (NSs). The fabricated NSs were characterized using sophisticated techniques. The developed Ag@SnO2-g-C3N4 NSs showed a well-defined spherical-shaped Ag NPs anchored to SnO2-g-C3N4 NSs. The synthesized NSs were applied for photocatalytic degradation of hazardous dyes and photoelectrochemical studies. A comparative investigation of Ag@SnO2-g-C3N4 NSs for the visible light-assisted photocatalytic degradation of Methylene blue (MB), Congo red (CR), and Rhodamine B (RhB) was performed. The photocatalytic degradation of MB, CR, and RhB reached ∼99% in 90 min, ∼98% in 60 min, and ∼94% in 240 min, respectively. The anchoring of Ag NPs to SnO2-g-C3N4 NSs further enhanced the visible light photocatalytic degradation of the dyes due to surface plasmon resonance and by lowering the recombination of the photogenerated electrons and holes. Further, high electron transfer ability of Ag@SnO2-g-C3N4 NSs was investigated by electrochemical impedance spectroscopy to understand the mechanistic insights of the excellent activity under visible light irradiation. Hence, the present study provides an environmentally benign approach for the synthesis and excellent visible light effective photocatalysis and photoelectrochemical performance.

Los Protistas presentan una organización celular Procarionte. Son organismos unicelulares, coloniales o pluricelulares. El tamaño varía entre especies, desde el protozoo microscópico de 2um, hasta algunas algas pardas que miden hasta 75m. A diferencia de los animales y hongos, la mayoría de los pluricelulares tienen formas simples sin tejidos especializados. Los protistas son de vida libre y otros forman asociaciones simbióticas con otros organismos. • Mutualismo: Ambas especies se benefician. • Parasitismo: El parásito vive en la superficie o dentro del huésped, y depende metabólicamente de él. La mayoría de los protistas se reproducen de manera asexual, otros de forma sexual, singamia y unión de gametos. La división o multiplicación bacteriana se detiene en el momento determinado en que las condiciones ambientales no son óptimas, como el oxígeno, disponibilidad de nutrientes, pH neutro y temperatura. Tiempo de Generación: Es el tiempo que demora la bacteria en multiplicarse. • Bacterias patógenas: 20 min. Enterobacterias, Staphylococcos. • Mycobacterias: 18-24 min. • Listeria monocytogenes: 50 min. Metabolismo de las bacterias: Metabolismo: Reacciones químicas integrales de anabolismo y catabolismo, donde ambos requieren energía la cual se encuentra almacenada en moléculas de ATP. Las bacterias patógenas obtienen la energía por síntesis química, es decir, son Quimioorganotrofas, que viven a expensas de materia orgánica, a través de la oxidación y fermentación de compuestos exógenos. ESTRUCTURA DE LAS BACTERIAS: Organelos: • Pared celular: 95% de las bacterias; género Mycoplasma no tiene. • Membrana plasmática. • Citoplasma. • Ribosomas. • Nucleoide o cromosoma bacteriano; no tienen un núcleo verdadero.

- by natalia iturriaga
- •
- Veterinary Medicine, Bacteriology, Medicina, Bacteria

This thesis reports observations on eleven patients made in two an a half years. The first histological study of teeth in E .D .S . is made, which shows calcification of the pulp, pulp stone formation and abnormalities in the dentine .... more

This review article evaluates the current impact of antibiofilm drugs including its delivery, efficiency of blocking cell attachment and molecular mechanisms of action that is conjugated or encapsulated with different types of biocompatible nanomaterials. It will lead to a better understanding of the antibiofilm drugs and their role in combating biofilms. It will also open new doors for the application of immobilized antibiofilm drugs.

- by Prof. Dr. Mohammad Mansoob Khan
- •
- Biofilms, Nanomaterials, Biofilm, Microbial biofilms

Objective: To analyze the evolution of the thickness, bacterial vitality, covering grade, and the structure after 2 and 4 days of aging in "non-disturbed" plaque-like biofilm (PL-biofilm). Method and Materials: Twenty healthy volunteers wore a specific appliance. After 2 days half of the samples were removed from the appliance. Posteriorly, after bacterial vital staining, samples were analyzed using a confocal laser scanning microscope. In the first volunteer, one of the disks was analyzed using a scanning electronic microscope. The same process was realized on the remaining disks after 4 days. Results: The thicknesses of the PL-biofilm after 2 and 4 days were not significantly different. The bacterial vitality changed significantly from 72.50 ± 15.50% to 57.54 ± 15.66% over time, which was in contrast to the covering grade (53.08 ± 18.03% and 70.74 ± 19.11%). The structure changed from an irregular surface and compact deepest layer with a high predominance of the coccus shape to a complex structure with voids in the deepest layer and a great proportion of bacillus-shaped bacteria. Conclusion: The PL-biofilm thickness remained practically constant, decreasing the bacterial vitality and increasing the covering grade over time. Regarding the structure, differences were principally bacterial disposition in the surface and bacterial shape. Clinically, the findings show that new control strategies for combating the oral biofilm should be focused on inhibiting bacterial adhesion to tooth surfaces, which would reduce biofilm formation.

- by Inmaculada Tomas
- •
- Dentistry, Biofilms, Dental Research, Microscopy

Two lab-scale Self Forming Dynamic Membrane BioReactors (SFD-MBR), equipped with 50 µm nylon meshes were set up and operated for the treatment of real municipal wastewater. Plastic carriers were added in one of the two bioreactors to generate a combination of the Integrated Fixed-ﬁlm Activated Sludge (IFAS) and the SFD-MBR technologies. Overall, the two systems performed very well, achieving excellent eﬄuent quality under steady state conditions and showing good resilience to extreme organic loading conditions. Continuous air scouring and periodical mesh cleaning by jet rinsing with tap water were eﬀective in maintaining stable and high productivity (membrane ﬂux around 67 L m2 h−1) over a period of 140 days. The application of the IFAS process resulted in lower production of excess sludge and improved denitriﬁcation. On the other hand, under the tested conditions the combined IFAS-SFD-MBR showed a higher tendency to mesh clogging with respect to the SFD-MBR.

Biofilmed biofertilizers have emerged as a new improved inoculant technology to provide efficient nutrient and pest management and sustain soil fertility. In this investigation, development of a Trichoderma viride–Me-sorhizobium ciceri biofilmed inoculant was undertaken, which we hypothesized, would possess more effective biological nitrogen fixing ability and plant growth promoting properties. As a novel attempt, we selected Me-sorhizobium ciceri spp. with good antifungal attributes with the assumption that such inoculants could also serve as biocontrol agents. These biofilms exhibited significant enhancement in several plant growth promoting attributes, including 13–21 % increase in seed germination, production of ammonia, IAA and more than onefold to twofold enhancement in phosphate solubilisation, when compared to their individual partners. Enhancement of 10–11 % in antifungal activity against Fusarium oxysporum f. sp. ciceri was also recorded, over the respective M. ciceri counterparts. The effect of biofilms and the M. ciceri cultures individual on growth parameters of chickpea under pathogen challenged soil illustrated that the biofilms performed at par with the M. ciceri strains for most plant biometrical and disease related attributes. Elicitation of defense related enzymes like L-phenylalanine ammonia lyase, peroxidase and polyphenol oxidase was higher in M. ciceri/biofilm treated plants as compared to uninoculated plants under pathogen challenged soil. Further work on the signalling mechanisms among the partners and their tri-partite interactions with host plant is envisaged in future studies.

- by Krishnashis Das and +1
- •
- Antifungal Activity, Bacterial Biofilms, Mesorhizobium

The primary objective of this study was to isolate and enumerate mercury-resistant bacteria and to compare their occurrence and distribution spatially and temporally along the Indian coasts. As coastal waters experience adverse effects of a variety of toxic chemicals and salt concentration that may play a role in resistance mechanism in mercury-resistant marine bacteria, investigations were carried out to see whether marine MRB have different ways to deal with toxic mercury and to examine their genetic make-up. The hypothesis put forth for this study that bacterial strains capable of Hg resistance can also tolerate, detoxify or biotransform a variety of other toxicants was examined. Experiments were carried out to understand the potential of a select set of MRB to tolerate and/or biotransform polychlorinated biphenyls (PCBs), tri-butyl tin (TBT), mercury, cadmium and lead to validate this hypothesis.

- by Jaysankar De
- •
- Microbiology, Biogeochemistry, Environmental microbiology, Ecotoxicology

The scientific community is showing an increasing interest in exploring the in vivo formation of the undisturbed human oral biofilm, because understanding the processes involved may open new avenues for interfering with the pathogenic properties of biofilms. The present chapter is focused on in vivo human models of undisturbed oral biofilm analysed by confocal laser scanning microscopy (CLSM). The different types of oral appliances and substrates used, the several microbiological and microscopic methods applied in combination with CLSM, as well as CLSM technical aspects are discussed. Finally, a new microscopic technique is described, the so called, confocal endomicroscopy, which will offer numerous exciting opportunities for the in vivo microscopic investigation in the field of Dentistry.

- by Inmaculada Tomas
- •
- Dentistry, Biofilms, Dental Research, Microscopy
- by Aleivi Pérez
- •
- Microbiology, Applied microbiology, Bacterial Pathogenesis, Pseudomonas aeruginosa

The modern clinical research on prostatitis started with the work of Stamey and coworkers who developed the basic principles we are still using. They established the segmented culture technique for localizing the infections in the males to the urethra, the bladder, or the prostate and to differentiate the main categories of prostatitis. Such categories with slight modifications are still used according to the NIH classification: acute bacterial prostatitis, chronic bacterial prostatitis, Chronic Pelvic Pain Syndrome (CPPS) and asymptomatic prostatitis. Prostatic inflammation is considered an important factor in influencing both prostatic growth and progression of symptoms of benign prostatic hyperplasia and prostatitis. Chronic inflammation/neuroinflammation is a result of a deregulated acute phase response of the innate immune system affecting surrounding neural tissue at molecular, structural and functional levels. Clinical observations suggest that chronic inflammation correlates with chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) and benign prostatic hyperplasia (BPH) and an history of clinical chronic prostatitis significantly increases the odds for prostate cancer. The NIHNIDDK classification based on the use of the microbiological 4-glasses localization test or simplified 2-glasses test, is currently accepted worldwide. The UPOINT system identifies groups of clinicians with homogeneous clinical presentation and is used to recognize phenotypes to be submitted to specific treatments.

Biocementation is a green treatment technique which makes use of microbially induced carbonate precipitation (MICP) process to enhance the geotechnical features of substandard soils. The objective of this study was to conduct a biocement test in laboratory-scale using native urease-producing bacteria to improve the surface strength of poorly graded soil. Selected sand samples were pre-mixed with native bacterial culture and the cementation solution before being compacted into their respective columns. After completing the biocement process, all the sand columns were allowed to air-dry at room temperature (26 o C) for 14 days before the treated sands were removed from their respective moulds. Unconfined compression strength (UCS) test was performed on the moulds to determine their strengths, while quick acid test and calcium carbonate (CaCO 3) content measurement were conveyed to analyse the precipitated CaCO 3 minerals. The results showed that the native urease-producing bacteria could bind soil particles together. The proficiency of this treatment process to improve the strength of soil samples varied among the specimen samples, leading to a non-homogeneous distribution of CaCO 3 contents in the specimens. The UCS test showed that the sand treated with native isolate NB 28 had the highest strength (0.219 N/mm 2), sustaining a force of 1.020 kN, while the control strain (Sporosarcina pasteurii DSM 33) had the lowest strength (0.143 N/mm 2) with a sustaining force of 0.697 kN. The findings in this study suggest that the native urease-producing bacteria isolated from Sarawak limestone cave can be used as alternative MICP agents for the biocement application for sustainability in the construction industry.

- by Armstrong I . Omoregie and +1
- •
- Environmental Science, Environmental Sustainability, Bacterial Biofilms, Biocementation

Microbial biofilm created huge burden in treatment of both community and hospital infections. A biofilm is complex communities of bacteria attached to a surface or interface enclosed in an exopolysaccharide matrix and protected from unfavorable conditions such as presence of antibiotics, host defense or oxidative stresses. Biofilms are often considered hot spot for horizontal gene transfer among same or different bacterial species. Furthermore, bacteria with increased hydrophobicity facilitate biofilm formation by reducing repulsion between the extracellular matrix and the bacterium. There is a marked increase in the rate of persons nonresponsive to antibiotic therapy for infections of the Urinary Tract (UTIs), burns and upper respiratory tract due to biofilm formations. It is estimated that 90% of nosocomial infections are mediated by biofilm. The role of biofilm in infections has become so great that the treatment of such antibiotic resistance infections is proving difficult and costly to health care systems. The biofilm related infections varied from dental plaque, destruction of prosthetic valve to death of cystic fibrosis patients. This review aims to provide a summary of role of bacterial biofilm and its clinical implications for the patients.

- by mohammad reza shakibaie and +1
- •
- Bacterial Biofilms

The focal points of the research in our lab are plasmid mediated antibiotic and metal resistance, Biofilm formation and its genes in hospital isolates of Acinetobacter. Quorum sensing and signal transduction in Acinetobacter and also enhancing bioremediation of heavy metals using genetic engineering organisms, cloning some genes responsible for biofilm formation and also we are using genetic engineered bacteria for decreasing the CO2 emission. All these steps are subject to elaborate control by numerous regulatory proteins and small effectors. We are working on biogenic nanometals for disruption of biofilm and introducing potent nano-drugs. Our goal is to achieve synthesis of a nano-drug with potent antimicrobial and antibiofilm activity and less toxicity. The important factor for my research group also is cost. The nanotechnology allows us to develop a cost effective drug Stages of biofilm formation from platonic cells especially for poor countries in Africa. My students are working in the molecular design of nano-drug and delivery system by bioinformatics. Recently we studied possibility of existence of antibiotic resistant islands (ARI) in bacterial chromosome like Pathogenicity Island and the genes in these islands can transfer effectively by integrons transposons or by plasmids to other bacterial strains. My team for the first time submitted three genes and integrons class 1 to GenBank NCBI and found new variant IMP-55 metallo-β

- by mohammad reza shakibaie
- •
- Bacterial Biofilms

Actinobacillus pleuropneumoniae is a Gram-negative bacterium that belongs to the family Pasteurellaceae. It is the causative agent of porcine pleuropneumonia, a highly contagious respiratory disease that is responsible for major economic losses in the global pork industry. The disease may present itself as a chronic or an acute infection characterized by severe pathology, including hemorrhage, fibrinous and necrotic lung lesions, and, in the worst cases, rapid death. A. pleuropneumoniae is transmitted via aerosol route, direct contact with infected pigs, and by the farm environment. Many virulence factors associated with this bac- terium are well characterized. However, much less is known about the role of biofilm, a sessile mode of growth that may have a critical impact on A. pleuropneumoniae pathogenicity. Here we review the current knowledge on A. pleuropneumoniae biofilm, factors associated with biofilm formation and dispersion, and the impact of biofilm on the pathogenesis A. pleuropneumoniae. We also provide an overview of current vaccination strategies against A. pleuropneumoniae and consider the possible role of biofilms vaccines for controlling the disease.

- by Dra. Alma Lilián Guerrero Barrera and +1
- •
- Bacterial Pathogenesis, Bacterial Biofilms, Actinobacillus pleuropneumoniae

This research evaluates the effect of both organic and ammonia loading rates and the presence of plants on the removal of chemical oxygen demand and ammonia nitrogen in horizontal subsurface flow constructed wetlands, 2 years after the start-up. Two sets of experiments were carried out in two mesocosms at different organic and ammonia loading rates (the loads were doubled); one without plants (control bed), the other colonized with Phragmites australis. Regardless of the organic loading rate, the organic mass removal rate was improved in the presence of plants (93.4 % higher for the lower loading rate, and 56 % higher for the higher loading rate). Similar results were observed for the ammonia mass removal rate (117 % higher for the lower loading rate, and 61.3 % higher for the higher loading rate). A significant linear relationship was observed between the organic loading rate and the respective removal rates in both beds for loads between 10 and 13 g m−2 day−1. The presence of plants markedly increase removal of organic matter and ammonia, as a result of the role of roots and rhizomes in providing oxygen for aerobic removal pathways, a higher surface area for the adhesion and development of biofilm and nitrogen uptake by roots.

- by Antonio Albuquerque and +2
- •
- Engineering, Environmental Engineering, Chemical Engineering, Civil Engineering

Bacteria in the natural environment form complexes which are closely associated with abiotic and biotic surfaces of solids and liquids. These bacterial communities are adherent to a surface, an interface or to each other and are known as biofilms. Biofilm formation has serious implications in industrial, environmental, public health and medical situations because they express biofilms-specific properties such as increased resistance to antibiotics, UV light and chemical biocides, increased rates of genetic exchange, altered biodegradability and increased secondary metabolite production. In the clinical context, it is estimated that about 60% of all microbial infections involve bacterial biofilms. The occurrence of biofilms in food processing environments can cause post-processing contamination leading to lower shelf life of products and transmission of diseases. The ability to control biofilm growth is an important issue because of health problem and economic losses. Researchers are trying to find green product rather than synthetic one that can be used as generally recognized as safe (GRAS). Plants produce an enormous number of natural products. Many plants extract contain phenol derivatives, terpenes, flavonoids etc. which have ability to suppress the microbial cell attachment and biofilm growth. The aim of this mini review is to combine most of the recently published work on biofilm inhibition (plant based inhibitor) and figure out the inhibition mechanism which can be safely used in food safety and human health issues.

- by MD. RAMIM TANVER RAHMAN
- •
- Food Science, Food Safety, Biofilms, Enzyme Inhibitors

Microbial biofilms are complex structures wherein the planktonic cells change their growth mode to the sessile form. This kind of growth is assisted by the formation of a matrix of extracellular polymeric substances (EPS) which encapsulates the bacterial cells within it and thus, provides an additional protection. These biofilms are highly resistant to high concentration of antibiotics and poses a great threat towards public health. These biofilms are even beyond the access of a normal human immune system and are involved in infections of teeth, lungs and many other diseases. There lies an immediate need to replace the extensive use of antibiotics with new emerging strategies. The review intends to provide an insight on the various perspectives of microbial biofilms including their formation, composition, mechanism of communication (Quorum sensing) and pathogenicity. Recent emerging strategies have also been discussed that can be considered for successful eradication or inhibition of biofilms and related infections.

- by Aleivi Pérez
- •
- Microbiology, Bacterial Pathogenesis, Bacterial Biofilms, Swarming

Biofilms are an ancient survival microorganism
strategy that allows the colonization of hostile
environments, host tissues or inert surfaces, even
under changing conditions. For pathogenic this
represents, a dispersal mechanism of infections.
Therefore, the study of biofilms is important to understand
new colonization strategies, antibiotic
resistance, and horizontal gene transfer, among
other mechanisms shared by microorganisms at
the consortia. The purpose of this review is to provide
a general understanding of these communities,
highlighting their importance in the environment
and interactions among species that form
them.

- by Abraham Loera Muro and +2
- •
- Microbial biofilms, Bacterial Biofilms
- by Livjot Sachdeva
- •
- Otolaryngology, Pediatrics, Biofilms, Tissue Engineering
- by Rodrigo Arthur
- •
- Prevention of Dental Caries, Bacterial Biofilms

Antimicrobial peptides (AMPs) are promising templates for the development of novel antibiofilm drugs. Despite the large number of studies on screening and optimization of AMPs, only a few of these evaluated the antibiofilm activity in physiologically relevant model systems. Potent in vitro activity of AMPs often does not translate into in vivo effectiveness due to the interference of the host microenvironment with
peptide stability/availability. Hence, mimicking the complex environment found in biofilm-associated infections is essential to predict the clinical potential of novel AMP-based antimicrobials. In the present study, we examined the antibiofilm activity of the semisynthetic peptide lin-SB056-1 and its dendrimeric derivative (lin-SB056-1)2-K against Pseudomonas aeruginosa in an in vivo-like three-dimensional (3-D) lung epithelial cell
model and an in vitro wound model (consisting of an artificial dermis and blood components at physiological levels). Although moderately active when tested alone, lin-SB056-1 was effective in reducing P. aeruginosa biofilm formation in association with 3-D lung epithelial cells in combination with the chelating agent EDTA. The dimeric derivative (lin-SB056-1)2-K demonstrated an enhanced biofilm-inhibitory activity as
compared to both lin-SB056-1 and the lin-SB056-1/EDTA combination, reducing the number of biofilm-associated bacteria up to 3-Log units at concentrations causing less than 20% cell death. Biofilm inhibition by (lin-SB056-1)2-K was reported both for the reference strain PAO1 and cystic fibrosis lung isolates of P. aeruginosa. In addition, using fluorescence microscopy, a significant decrease in biofilm-like structures associated
with 3-D cells was observed after peptide exposure. Interestingly, effectiveness of (lin-SB056-1)2-K was also demonstrated in the wound model with a reduction of up to 1-Log unit in biofilm formation by P. aeruginosa PAO1 and wound isolates. Overall, combination treatment and peptide dendrimerization emerged as promising strategies to improve the efficacy of AMPs, especially under challenging host-mimicking conditions. Furthermore, the results of the present study underlined the importance
of evaluating the biological properties of novel AMPs in in vivo-like model systems representative of specific infectious sites in order to make a more realistic prediction of their therapeutic success, and avoid the inclusion of unpromising peptides in animal studies and clinical trials.

- by Andrea C. Rinaldi
- •
- Biofilms, Antimicrobial Peptides, Antimicrobials, Dendrimers

This paper focuses on the last generation methods for the characterization of biodeteriogens on historical artifacts. New "culture independent" technologies based on DNA obtained from environmental samples, which have replaced the previous culture-dependent methods, are experiencing a real boom and revolutionized the field of microbial ecology. rhese methods are based conceptually on metagenomics and, technically, on the so-called NGS (Next-Generation Sequencing) technologies. Metagenomic analysis is defined as the direct genetic analysis of genomes contained in an environmental sample. rhe leS technologies are characterized by a power and depth of sequencing totally unthinkable a few years ago and allow the identification also of the rarest species in a community. Even in their simplest declination, that is, the NGS sequencing of amplicons obtained with universal primers, the amount of data generated ranges from hundreds to thousands (for the Roche technology) in the millions-hundreds of millions (for the Illumina platforms).

- by Valentina Cinieri and +2
- •
- Cultural Heritage, Biofilms, Conservation Biology, Molecular Biology
- by Wuddan Nadhirah and +1
- •
- Microbiology, Biofilms, Biocorrosion, Applied and Environmental Microbiology

Biofilms are sessile communities of microorganisms growing on material surfaces and embedded in self-accumulated extracellular polymers. A comprehensive analysis of physical, chemical and biological factors including hydrodynamic and nutrient conditions that regulate their formation is required to adequately gain insight to this complex multicellular microbial life style. Reproducible experimental models that consider all the conditions under which they grow and develop also remain a required tool for studying the biofilms. As a result of its ability to create hydrodynamic and nutrient conditions coupled with continuous and non-destructive ability to grow biofilms, flow cell technology has become one of the most recently patronised models used to study microbial biofilms. This article focuses on recent advancements, principles and practical application of flow cell technology to study microbial biofilms.

- by Wan Rosmiza Zana Wan Dagang
- •
- Bacterial Biofilms

In the present study, adsorption of Cu(II) ions from aqueous solutions was evaluated using new thin adsorptive membranes modified with silver nanoparticles. Membranes were prepared from chi-tosan/polyacrylamide polymer blend. The variation of adsorption process was investigated in batch sorption mode. Infrared absorption spectra were applied for chemical characterization of the prepared polymer blend. Thermogravimetric analysis showed that addition of polyacrylamide to chitosan increased its thermal stability. The kinetics and thermodynamic parameters of Cu(II) ions adsorption onto the membranes were studied by removal experiments of Cu(II) ions from standard aqueous solutions. The kinetic data fitted to the traditional Lagergren adsorption kinetic equations. Thermodynamic studies indicated endothermic (H • > 0) and spontaneous (G • < 0) adsorption together with entropy generation (S • > 0) at the solid/liquid interface process. Regeneration experiments showed that the newly prepared membranes could be reconditioned without significant loss of its initial properties even after three adsorption–desorption cycles. The results suggest that the prepared composite membranes can be efficiently applied for the adsorptive removal of Cu(II) ions from natural water samples. Antimicrobial activity was tested against two gram negatives, two gram positives and Candida sp. microbes and they showed a remarkable bioactivity indicating the capability of applying such membranes for a dual action.

- by Ahmed AbdElrazak and +1
- •
- Nanotechnology, Antimicrobial activity, Bacterial Biofilms
- by Tommaso Iannitti
- •
- Biofilms, Microbial biofilms, Aesthetic Medicine, Bacterial Biofilms

Streptococcus mutans (S. mutans) has been identified as a major etiologic agent of human dental caries and forms a significant proportion of oral strepto-cocci in carious lesions. This study investigates the correlation of surface properties (effect of contact angle [CA] and free surface energy) on three restorative materials (zirconia, nickel-chromium-molybdenum alloy and composites) used in dental prosthetics with bacterial adhesion to S. mutans. Ten samples of each material (zirconia, nickel-chromium-molybdenum alloy and composites) of 8 mm diameter and 2.5 mm thickness were used. Aqueous CA measurements, free surface energy and bacterial adhesion to the sample surfaces were performed. Bacterial adhesion is determined by planting samples in the blood agar cultures and using an electron microscope (scanning electron microscopy [SEM]). The highest values of bacterial adhesion are found in composites, followed by the metal alloy, while the lowest values are observed in zirconia. Measurements show that zirconia has 17 bacteria; Ni-Cr-Mo alloy has 65, while the composite has 80 bacteria. The composites showed the highest degree of bacterial adhesion, compared to the other investigated materials, which correlates with the free surface energy of the samples (24.31 mJ/m 2 for zirconia, 31.78 mJ/m 2 for Ni-Cr-Mo alloy and 48.82 mJ/m 2 for the composite).

- by Arianit Reka and +1
- •
- Biofilms, Dental Health, Dental Materials, Dental Implants

Staphylococci are Gram-positive bacteria that are ubiquitous in the environment and able to form biofilms on a range of surfaces. They have been associated with a range of human health issues such as medical device-related infection, localized skin infection, or direct infection caused by toxin production. The extracellular material produced by these bacteria resists antibiotics and host defence mechanism which complicates the treatment process. The commonly reported Staphylococcus species are Staphylococcus aureus and S. epidermidis as they inhabit human bodies. However, the emergence of other staphylococci, such as S. haemolyticus, S. lugdunensis, S. saprophyticus, S. capitis, S. saccharolyticus, S. warneri, S. cohnii, and S. hominis, is also of concern and they have been associated with biofilm formation. This review critically assesses recent cases on the biofilm formation by S. aureus, S. epidermidis, and other staphylococci reported in health-related environments. The control of biofilm formation by staphylococci using natural compounds is specifically discussed as they represent potential anti-biofilm agents which may reduce the burden of antibiotic resistance.

- by Wee Sim Choo
- •
- Natural Products, Biofilms, Natural Products Chemistry, Antimicrobials
- by Jakob Wallinga
- •
- Archaeology, Geochemistry, Malacology, Quaternary Geology
- by Hadeel Musafer and +1
- •
- Antibiotic Resistance, Bacterial Biofilms
- by Michael Friedman
- •
- Engineering, Bioinformatics, Genetics, Chemistry

Biofilm forms with the colonization of different microorganism resulting in a microbial community which is complex and diverse in nature. Biofilms are enclosed with different microbial colonies in a matrix known as extracellular polymeric substance. Microorganisms together in this complex structure communicate through cell signaling molecules. This process is known as quorum sensing which helps in maintaining the complexity and diversity. Biofilms are involved in causing various infections in human beings. Oral cavity and wounds are very common two sites where biofilm formation takes place. The complexity of a biofilm makes it tenacious and it’s tough to eradicate completely. There are several conventional methods such as physical, chemical, antibiotics, antiseptics and anti-biofilm agents for the eradication of dental/periodontal biofilms and biofilms associated oral wounds. Thus, various novel approaches can be proposed, one of them is Nanotechnology. Its extensive application in dentistry can be very helpful in curing various periodontal and dental diseases. Nanoparticles are one of new emerging potent system which can be really helpful in the complete eradication of complex biofilms due to their high anti-microbial properties. In this review, we have attempted to discuss dental/periodontal biofilms; oral wounds, their relation with oral biofilm microbes and their treatment as well as conventional methods of treatment available till now. With this comprehensive review, it is proposed that with the help of nanotechnology, various nanoparticles can be designed and an improvement can be done to the available methods or some new methods.

- by Suruchi Chaudhary
- •
- Bionanotechnology, Bionanoscience, Nanotecnology, Bacterial Biofilms