Arsenis Tsiotsias - Academia.edu (original) (raw)

Papers by Arsenis Tsiotsias

Animals, 2021

Dairy sheep farming is a vital sector of the agricultural economy in Greece. Information on the e... more Dairy sheep farming is a vital sector of the agricultural economy in Greece. Information on the effect of the farming system on sheep milk characteristics is critical for producing dairy products with improved nutritional value according to the current guidelines for healthy food consumption. This study aimed to investigate the basic composition, physicochemical characteristics, fatty acid composition, and nutritional indices of milk produced in intensive and semi-intensive sheep farms. Bulk tank milk samples from 20 intensive and 20 semi-intensive sheep farms were examined. Sheep in the intensive farms were kept indoors and were fed with roughage, silage, and concentrates. Sheep in the semi-intensive farms were kept indoors during the night and were moved to the pastures during the day. Sheep were fed with roughage, silage, and concentrates in combination with grazing. Milk composition and somatic cell count were determined with automatic analyzers. The physicochemical characterist...

Microbial Ecology in Health and Disease, 2004

Along with other endogenous and exogenous factors which may interfere in the regulation of variou... more Along with other endogenous and exogenous factors which may interfere in the regulation of various pathways that control the intestinal microflora, physical and psychological stress seem to play a crucial role. In order to estimate the influence of psychological stress on the intestinal microflora composition, repeated restraint stress was used as a stress paradigm. Faecal indicator bacteria (aerobic and anaerobic) were used to assess the microbiological profile of the intestinal flora. Faecal samples were collected from adult male Wistar rats (Kuo/Ioa/rr) before and after repeated restraint stress. Serial dilutions were performed in Ringer solution followed by spreading on MacConkey agar that had been incubated at 378C overnight. An aliquot of each solution was heated at 758C for 10 min, followed by spreading in lactose-sulfite (LS) broth. Numbers of Clostridium perfringens were estimated by performing decimal dilutions in the LS broth that had been incubated in a water bath at 468C overnight. Characteristic colonies of Escherichia coli were counted and identified using the API 20E System. Numbers of C. perfringens were estimated and compared to those of E. coli. Higher numbers of vegetative forms of the anaerobic bacterial indicator C. perfringens were found in stress-exposed animals as compared with controls and with pre-stress conditions. The end of the stress exposure found the numbers of C. perfringens back to initial levels or even below.

Microbial Ecology in Health & Disease, 2001

Bacterial indicators, including total coliforms, fecal coliforms, total Streptococci, Enterococci... more Bacterial indicators, including total coliforms, fecal coliforms, total Streptococci, Enterococci and Clostridium perfringens, were evaluated in alpine lake water environments at elevated altitudes in the Pindos mountain region. Classical methods and techniques were used for the isolation and characterization of indicator microorganisms and a selective nutrient medium supplemented with lactose-sulphite (LS) for the rapid determination of C. perfringens. In most lake samples examined, low numbers of microorganisms were enumerated in the order 10 1-10 3 , whereas no Enterococci were present. Vegetative forms of C. perfringens were not recovered in any of the lake samples, on the contrary spore forms where detected in all samples. Finally, determination of levels of various metal ions such as Cu, Ni, Mn, Zn, Fe and Pb in lake waters revealed very low concentrations for these metals. Our results demonstrated a range of indicator microorganisms present in low numbers and also certain metal ions at low concentrations, thus, presenting no immediate concern for pollution to the surrounding ecosystem of the Pindos mountain range.

Microbial Ecology, 2007

The aim of the present study was to evaluate the alterations that may take place in the bacterial... more The aim of the present study was to evaluate the alterations that may take place in the bacterial genital tract flora in the absence of ovarian hormones. The role of hormone replacement therapy was also assessed. For this purpose, various bacteria were identified from the vaginal flora of ovariectomized and sham operated female rats, following the Bergey's manual criteria. The data of this study showed that substantial differences exist in the vaginal bacterial microflora between ovariectomized and normal cyclic rats. Ovariectomy was associated with a lower total bacterial load that may be due mainly to the absence of Lactobacillus. Anaerobic bacteria were also absent. Streptococcus and Enterococcus were also not favored in an environment lacking the ovarian hormones. In contrast, C. perfringens, Bacteroides, S. epidermidis, and S. aureus were detected in high numbers in ovariectomized rats. In terms of the impact of hormone replacement therapy on vaginal flora, only estradiol (EE2) restored Lactobacillus levels in ovariectomized rats, whereas all hormonal schemes used brought Streptococcus, Clostridium lec (−), and C. perfringens, the spore and vegetative forms, close to those detected in normal cyclic female rats. In conclusion, ovarian hormones appeared to be regulatory factors that favor the presence of a broad variety of bacteria, which are members of the normal genital tract flora. On the other hand, ovariectomy modifies the vaginal microbial profile, and hormone replacement therapy based mainly on schemes containing EE2 could alleviate this disturbance.

Comparative Immunology, Microbiology and Infectious Diseases, 2006

Colonization by Bifidobacterium occurs generally within 4 days of life. The new method FISH has b... more Colonization by Bifidobacterium occurs generally within 4 days of life. The new method FISH has been applied for molecular detection of Bifidobacteria. The study was carried out on 26 healthy newborns delivered by vaginal delivery. Breast-fed infants harbor a gastrointestinal flora characterized by an increased concentration of Bifidobacterium cells (by a factor of 1.75). In artificial alimentation, some infants either did not harbor any Bifidobacterium or showed lower numbers of Bifidobacterium. Moreover, male newborns show higher numbers of Bifidobacterium, but in both sexes the predominance of Bifidobacterium is evident after maternal alimentation.

Poultry Science, 2007

The development of treatments to reduce bacterial numbers on poultry carcasses is important for t... more The development of treatments to reduce bacterial numbers on poultry carcasses is important for the overall hygienic quality of birds. The important washing effect of the immersion chilling procedure is discussed. Systematic monitoring of fecal bacterial indicators as well as some classic pathogens was performed at selected critical points in a water chiller ecosystem. Clostridium perfringens, fecal coliforms, Enterococcus sp., and Streptococcus sp. were found in all water chiller samples. The temperature of the chiller ecosystem varied according to

Microorganisms

Plants have long been thought to contribute to health promotion due to their fiber and phenolic c... more Plants have long been thought to contribute to health promotion due to their fiber and phenolic content, as well as their inherent biological potential. The bioactive derivatives of medicinal plants are a valuable resource in the fight against serious diseases all around the world. The present review focuses on the current state of knowledge on the usage and medicinal applications of plant bioactives. Issues concerning the effect of aromatic plant derivatives on human gut microbiota and their antimicrobial and anti-inflammatory potentials are discussed and worth further exploring.

The aim of the present thesis is the investigation of the distribution of C.perfringens in aquati... more The aim of the present thesis is the investigation of the distribution of C.perfringens in aquatic ecosystems. Namely the lakes Kastoria and loannina, the rivers Voidomatis, Aoos, Louros, Kalamas as well as the stream Soulou of Ptolemaida city. Specifically the distribution of this bacterium was examined at three levels. At the level of space (spatial distribution) with the final aim to show the existence of specific and non specific sources of fecal pollution, since this bacterium constitutes an indicator of fecal pollution. At the level of time (seasonal distribution) with the final aim to provide information on the life cycle of the involved bacterium, as well as on the type of ecosystems (open-closed systems). Finally at the level of cross-correlations with biotic and abiotic factors. The methods used for the realization of this thesis were: The method of a selective nutrient medium supplemented with lactose- sulphite (LS) proposed for rapid enumeration and identification of C. ...

The understanding of the pathogenesis of vaginitis is directly dependent upon the factors which p... more The understanding of the pathogenesis of vaginitis is directly dependent upon the factors which promote the colonization by bacterial genital microflora. Disruption of the bacterial barrier function afforded by the predominant microflora can lead to colonization by pathogenic or opportunistic pathogenic subdominant species. The present study focused on the effects of stress on the bacteria of the vaginal flora. For this purpose two types of psychological stress were employed: acute and subacute mild unpredictable stress. Estimation of the vaginal flora of 22 Wistar rats was performed according to the distinct phases of the estrous cycle: PE (proestrous), E (estrous), ME (metestrous), and DE (diestrous). Bacteria isolated from the vaginal flora were identified following Bergey’s Manual criteria. Escherichia coli, Clostridium, and Clostridium perfringens (vegetative and spore forms), showed increased numbers at PE-E after acute and subacute stress. Enterococcus was increased after acu...

Σκοπός της παρούσας διατριβής είναι η διερεύνηση της κατανομής του κλωστηριδίου του διαθλαστικού ... more Σκοπός της παρούσας διατριβής είναι η διερεύνηση της κατανομής του κλωστηριδίου του διαθλαστικού (C.perfringens) σε υδάτινα οικοσυστήματα, όπως των λιμνών Καστοριάς και Ιωαννίνων, των ποταμών Βοϊδομάτη, Αώου, Λούρου, Καλαμά καθώς και του ρέματος Σουλού Πτολεμαΐδας. Συγκεκριμένα εξετάστηκε η κατανομή του βακτηρίου αυτού σε τρία επίπεδα. Σε επίπεδο χώρου (χωρική κατανομή) με απώτερο σκοπό να καταδειχθούν σημειακές και μη σημειακές πηγές κοπρανώδους μόλυνσης, δεδομένου ότι το βακτήριο αυτό αποτελεί δείκτη κοπρανώδους μόλυνσης. Σε επίπεδο χρόνου (χρονική κατανομή) με απώτερο σκοπό να εξαχθούν πληροφορίες για τον κύκλο ζωής του βακτηρίου, καθώς και για τον τύπο των οικοσυστημάτων (ανοιχτά-κλειστά συστήματα). Σε επίπεδο συσχετίσεων με βιοτικούς και αβιοτικούς παράγοντες. Οι μέθοδοι που χρησιμοποιήθηκαν για την πραγματοποίηση της διατριβής αυτής είναι η μέθοδος του υγρού θρεπτικού μέσου LS, η μέθοδος FISH (Fluorescence in situ hybridization) και μετρήσεις φυσικοχημικών παραμέτρων. Τα αποτε...

Anaerobe, 2011

The development of the gut is controlled and modulated by different interacting mechanisms such a... more The development of the gut is controlled and modulated by different interacting mechanisms such as, genetic endowment, intrinsic biological regulatory functions, environment influences and last but no least, the diet influence. Considered together with other endogenous and exogenous factors the type of feeding may interfere greatly in the regulation of the intestinal microbiota. During the last years molecular methods offer a complementarity to the classic culture-based knowledge. FISH has been applied for molecular evaluation of the microbiota in newborns delivered by vaginal delivery. Eleven probes/probe combinations for specific groups of faecal bacteria were used to determine the bacterial composition in faecal samples of newborns infants under different types of feeding. Breast-fed infants harbor a fecal microbiota by more than two times increased in numbers of Bifidobacterium cells when compared to formula-fed infants. After formula-feeding, Atopobium was found in significant counts and the numbers of Bifidobacterium dropped followed by increasing numbers in Bacteroides population. Moreover, under formula feeding the infants microbiota was more diverse.

Microbial Ecology in Health and Disease, 2000

... Different serovar names are based on the geographical location where the disease occurs: S.du... more ... Different serovar names are based on the geographical location where the disease occurs: S.dublin, S. montevideo, S ... is due to contamination of the eggshell with faecal material in the hen'scloaca or after laying ... There is seasonal variation with a peak in the autumn and winter. ...

Microbial Ecology in Health and Disease, 2006

Objective: The aim of this study was to evaluate the presence of Enterobacteriaceae in different ... more Objective: The aim of this study was to evaluate the presence of Enterobacteriaceae in different locations of the Evros-Ardas river ecosystem at the borderline of Greece-Turkey. Materials and methods: Usual filter methods were applied for the collection of water samples from the riverside subjected to waste and/or borderline polluted stream. Sampling was accomplished during 3 months, from January to March. A total of 150 strains were isolated and identified by API Mérieux. The antibiotic resistance profiles were performed according to CLSI; phylogeny analysis was performed by RAPD (random amplification polymorphic DNA analysis); integron class I, II and III were detected by PCR amplification of integrases I and II by using degenerated primers. The detection of the classes of integrons was performed after RsaI digestion of the PCR products and agarose gel electrophoresis. The antibiotic gene cassettes were also generated by PCR. Results: In all, 90% of the isolates were usual environmental strains without antibiotic resistance. Resistance to ampicilllin, amoxicillin, and/or ampicillin'/sulbactam and several cephalosporins was detected in 12 strains. Resistance to tetracycline and chloramphenicol was observed in two isolates; resistance to nalidixic acid and to fluoroquinolones was detected in three strains. Finally, resistance to sulfamethoxazole and trimethoprim was observed in four isolates. Integron class I was detected in four isolates and class II in two of them. Several profiles were identified by RAPD and some unique types. Conclusion: It has been shown that plasmids containing b-lactamase, tetracycline and chloramphenicol genes as well as integron class I and II contribute to the pathogenic profiles of the isolates of the region. According to our results four locations represented environmental niches of pathogenic and antibiotic-resistant Enterobacteriaceae, namely the locations Ardas, Elaia bridge, Rizia and Kastanies and Evros Nea Vissa. Further investigation must be undertaken to control the microbial pollution of the riverside in Evros.

Microbial Ecology in Health & Disease, 2006

Food Microbiology, 2002

Soft whey cheese'Anthotyros' has the following characteristics: moisture content 65%, protein con... more Soft whey cheese'Anthotyros' has the following characteristics: moisture content 65%, protein content 9?6%, fat content 16?6%, salt concentration in the aqueous phase below 1% and pH 6?4. The average counts of the product were 4?54, 3?80, and 1?2 log cfu g À1 for aerobic mesophilic bacteria, yeasts and Enterobacteriaceae, respectively.The feasibility of gamma radiation for eliminating Listeria monocytogenes Scott A inoculated into the freshly produced product, and following its counts during refrigerated storage at 4 and 101C under vacuum packaging was investigated. Cheese samples were exposed to doses of 0?5, 2 and 4 kGy of gamma irradiation at 41C. Irradiation at 0?5 kGy slightly reduced the aerobic mesophilic bacteria counts, while irradiation doses at 2 and 4 kGy reduced the microbial load by approximately 1^2 log cycles. Enterobacteriaceae could not be detected in irradiated samples. Irradiation decreased the yeast population which was detected during later stages of storage. Molds were not detected in any of the samples. The calculated D 10-value for L. monocytogenes was 1.38 kGy. Surviving microbial cells could be detected throughout the entire period of 42 days storage. Sensory scores indicated that irradiation doses up to 4 kGy do not adversely a¡ect 'Anthotyros' sensory properties.

Food Microbiology, 2005

The effect of ozonation in aqueous solution (O 3 concentration=1 mg/l, time of ozonation: 60 and ... more The effect of ozonation in aqueous solution (O 3 concentration=1 mg/l, time of ozonation: 60 and 90 min) on the shelf-life of shucked, vacuum-packaged mussels, stored under refrigeration was studied by monitoring the microbiological, chemical and sensory changes occurring in mussel samples, for a period of 12 days. Non-ozonated vacuum-packaged mussels served as the control sample. Ozonation affected populations of bacteria namely, aerobic plate count (APC) (0.7-2.1 log cycle reduction), Pseudomonas spp. (0.5-1.1 log cycle reduction) and H 2 S-producing bacteria (1.1-2.5 log cycle reduction), Brochothrix thermosphacta (0.3-1.4 log cycle reduction), lactic acid bacteria (0.3-0.8 log cycle reduction) and Enterobacteriaceae (0.5-1.5 log cycle reduction). The effect of ozonation was more pronounced at the longer time of ozonation. Of the chemical indicators of spoilage monitored, trimethylamine values of all mussel samples remained relatively low throughout the entire storage period, attaining values of 7.5, 6.0 and 6.4 mg N/100 g for the control and ozonated for 60 and 90 min samples, respectively, on day 12 of storage. Total volatile basic nitrogen (TVB-N) values similarly remained relatively low (p20 mg N/100 g) until day 6 of storage, and increased to 31.9, 24.2 and 26.9 mg N/100 g mussel meat for the control and ozonated for 60 and 90 min samples, respectively, on day 12 of storage. Initial TBA values were surprisingly high (30-35 mg MA/kg) and decreased to 23.0, 21.7 and 13.3 mg MA/kg mussel meat on day 12 of storage for the control and the ozonated for 60 and 90 min samples, respectively. Sensory evaluation (odor, taste and texture) of cooked mussels showed a good correlation with bacterial populations. On the basis of sensory analyses, a shelf-life of 12 days was obtained for vacuum-packaged mussels ozonated for 90 min as compared to a shelf-life of 9 days for the control sample.

European Food Research and Technology, 2005

The effects of ozone in aqueous solution on the shelf life of whole, vacuum-packaged rainbow trou... more The effects of ozone in aqueous solution on the shelf life of whole, vacuum-packaged rainbow trout, stored under refrigeration (4±0.5 • C) were studied by monitoring the microbiological, chemical and sensory changes for a period of 15 days. Vacuum-packaged non-ozonated trout served as the control sample. Ozonation affected populations of bacteria namely, mesophilic aerobic bacteria, Pseudomonas spp. and H 2 S-producing bacteria until day 11 of storage, Brochothrix thermosphacta, lactic acid bacteria and Enterobacteriaceae until day 8 of storage. Trimethylamine (TMA) values of all rainbow trout samples remained low (<3 mg N/100 g) until day 11 of storage, and then increased to 12.2, 8.9 and 4.7 mg N/100 g for the control and the samples ozonated for 60 and 90 min, respectively on day 15 of storage. Total volatile basic nitrogen (TVB-N) values remained relatively constant (20-25 mg N/100 g) until day 11 of storage, but increased to 61.1, 37.6 and 39.4 mg N/100 g flesh for the control and ozonated specimen for 60 and 90 min, respectively on day 15 of storage. Thiobarbituric acid (TBA) values remained relatively constant (1-3 mg MA/kg flesh) until day 12 of storage but increased to 8.4, 6.4 and 3.8 mg MA/kg flesh on day 15 of storage for the control and the ozonated trout for 60 and 90 min, respectively. Sensory evaluation (odor, taste and texture) of cooked rainbow trout showed a very good correlation with bacterial populations. On the basis of both sensory and microbiological data, a shelf life of 10 and 12 days was obtained for ozonated, vacuum-packaged and refrigerated rainbow trout at 60 and 90 min, respectively.