Papers by Ioannis Boziaris
Journal of Pest Science, Jun 12, 2019
Stored-product insects can transfer a wide range of serious pathogens involved in human health. T... more Stored-product insects can transfer a wide range of serious pathogens involved in human health. The close contact of these insects with the food production chain makes these species extremely dangerous as carriers of severe infections. In addition, pathogenic bacteria, such as members of Enterococcus, are often resistant to antibiotics commonly used for human therapy. Herein we identified, using Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS), Enterococcus and coliform species isolated from 17 strains of different insect species associated with durable stored products. The antibiotic susceptibility of the isolated strains was also evaluated. MALDI-TOF MS revealed mainly the presence of Enterococcus (E. faecium, E. phoeniculicola and E. casseliflavus) and Enterobacter (Eb. cloacae and Eb. asburiae). E. casseliflavus was resistant to all antibiotics tested, while E. faecium and E. phoeniculicola were resistant to sulphonamides. Among E. faecium isolates, approx. 20% were found to be resistant to tetracycline, while Eb. cloacae and Eb. asburiae showed resistance to erythromycin. The current series of data clearly indicates that certain bacteria of the genera Enterococcus and Enterobacter are very common in stored-product insects, and, under certain circumstances, may seriously endanger public health, through potential introduction of antibiotic resistance.
Trends in Food Science and Technology, Feb 1, 2022
International Journal of Food Microbiology, Aug 1, 2020
The total cultivable microbiota of the ice-stored European sea bass (Dicentrarchus labrax), the m... more The total cultivable microbiota of the ice-stored European sea bass (Dicentrarchus labrax), the most important commercial fish species of the Mediterranean aquaculture, was determined using 16S rRNA gene sequence analysis. High Resolution Melting (HRM) curve profiles and sequencing analysis (V3-V4 region of the 16S rRNA gene) were used respectively for the differentiation and identification of the collected isolates from six time intervals (day 0, 4, 8, 12, 14 and 16) while fish were stored in ice. HRM analysis differentiated the unknown microbiota in ten groups (208 isolates) and in two single isolates based on their HRM curve profiles. The isolates with HRM profiles which were > 91% similar within each group were found to belong to the same species using sequencing analysis. Thus, the ten groups consist of representatives of Psychrobacter glacincola, Ps. alimentarius, Ps. cryohalolentis, Ps. maritimus, Ps. fozii, Pseudomonas sp., Paeniglutamicibacter sp., Carnobacterium sp., Leucobacter aridicolis and Bacillus thuringiensis. Based on this approach, Ps. cryohalolentis was found to be the most dominant phylotype at the beginning of fish shelf-life compared to other species. The abundance of this bacterium decreased throughout storage, while Ps. glacincola increased and dominated at the time of the sensory minimum acceptability (day 14) and rejection (day 16). To conclude, HRM could be used for the rapid determination of sea bass microbiota, using the representatives of each group as reference bacterial strains, in order for scientists to solve rapidly stakeholders problems related with microbial quality or safety of fish.
Lebensmittel-Wissenschaft & Technologie, Mar 1, 2016
Exploration of initial and spoilage microbiota grown on plates of whole sea bream stored aerobica... more Exploration of initial and spoilage microbiota grown on plates of whole sea bream stored aerobically at 0 (ice), 5 and 15 °C, was conducted by 16S rRNA gene sequence analysis. The course of spoilage was recorded by monitoring microbiological, sensory and chemical changes. Shelf-life of sea bream determined by sensory assessment was 16, 5 and 2 days at 0 (ice), 5 and 15οC, respectively. Pseudomonas spp. was the dominant spoilage population of whole sea bream at all temperatures tested. A sum of 144 colonies were isolated from TSA (Tryptone Soy Agar) plates and identified by genotypic approach at the beginning and at the sensory rejection time points. Regarding initial microbiota, Pseudomonas fragi was the most abundant compared to the rest bacteria (Pseudomonas fluorescens, Enterobacter hormaechei, Chryseobacterium carnipullorum). P. fragi was also the dominant microorganism of fish stored at 0 and 5, while P. fluorescens at 15 οC. Concluding, genotypic approach gives accurate identification of the dominant spoilage microorganisms providing us with valuable information regarding microbiological spoilage of fish.
Applied sciences, Jan 17, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Foods, Mar 8, 2023
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Food Microbiology, May 1, 2022
Vacuum-packed hot smoked rainbow trout fillets from two different smokehouses of Greece were stor... more Vacuum-packed hot smoked rainbow trout fillets from two different smokehouses of Greece were stored at 2 and 7.9 °C. Microbiological, sensory, and physicochemical changes were monitored. Microbial communities grown on MRS of three different pHs (5.4, 6.4 and 7.4) were also classified and identified using Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Shelf-life was found to differ between products from the two smokehouses (A: 104 and 45 days, B: 100 and 45 days, at 2 and 7.9 °C, respectively). At the time point that sensory rejection was recorded, counts on MRS were found at higher population levels than the other microorganisms tested, almost in all cases. Out of the 567 colonies isolated from MRS of three different pHs, 71 classified as Enterococcus spp., 383 as Candida spp. and 113 as Lactobacillus spp.. Candida zeylanoides dominated exclusively in fillets from the smokehouse A during storage at 2 °C, while Lactobacillus sakei dominated clearly against C. zeylanoides at 7.9 °C, in all pH values. For the smokehouse B, C. zeylanoides or Enterococcus faecalis found to dominate initially in MRS of three pHs, C. zeylanoides, and/or Candida famata in the middle and/or the time point that sensory rejection was recorded at 2 °C, while Lactobacillus curvatus or E. faecalis at 7.9 °C. This study reveals the predominant cultivable spoilage microbiota of vacuum-packed hot smoked rainbow trout, and provides valuable information to the researcher and producers towards the production of more stable products with improved shelf-life.
Critical Reviews in Food Science and Nutrition
In this review we propose the use of telomeric length (TL) as an authenticity marker that could p... more In this review we propose the use of telomeric length (TL) as an authenticity marker that could provide an alternative method for differentiating fish and seafood samples or detecting fraud. Considering the ever-growing number of incidents of economically motivated fish and seafood adulteration using even more sophisticated methods to overcome current authenticity markers, the need to identify novel authenticity markers becomes essential. The TL of fish and seafood depends on individual characteristics (e.g., sex, age) and the environmental stimuli (e.g., temperature, water quality) to which these are exposed. Hence, both wild marine and freshwater populations occupying different geographical origin habitats might differ substantially because of the environmental cues affecting them. Moreover, the implementation of various rearing practices in aquaculture, such as different levels of fish and seafood density and increased ambient noise combined with site-specific environmental cues could affect TL, providing regulatory authorities with valuable information by distinguishing wild from reared populations and organic from conventional ones. in the present review the effects of both the environmental conditions and individual characteristics on the telomeric stability of fish and seafood telomeres are discussed, suggesting TL as a potential prospect authenticity marker that could be used to prevent fish and seafood adulteration.
Food Microbiology, 2018
Cephalopods are highly appreciated with increasing demand seafood, but are also very perishable a... more Cephalopods are highly appreciated with increasing demand seafood, but are also very perishable and deteriorate fast mainly due to microbiological spoilage. For this reason exploration of bacterial communities through 16S Next Generation Sequencing (NGS) and Volatile Organic Compounds (VOCs) analysis was performed. Furthermore, sensory evaluation, classical microbiological analysis, Total Volatile Base-Nitrogen/TVB-N and Trimethylamine-Nitrogen/TMA-N determination were also carried out. Shelf-life of thawed cuttlefish (Sepia officinalis) stored at 2°C determined by sensory evaluation was 4 days. Aerobic Plate Counts (APC) reached the levels of 6.6 log cfu/g. The initial and final population of all spoilage microorganisms enumerated with selective media was under detectable levels with the exception of Pseudomonas. Based on 16S NGS analysis, Psychrobacter were the dominants among others, e.g. Pseudomonas, Shewanella, Comamonas, Carnobacterium, Vagococcus, of the initial microbiota. Psychrobacter was also the dominant microorganisms of the spoiled cuttlefish. TVB-N and TMA-N increased considerably only at the late stages of storage. A plethora of VOCs were produced and some exhibited an increasing profile throughout storage, making them promising molecules as freshness indicators in contrast to TVB-N and TMA-N. The application of next generation sequencing revealed the microbiota that escapes the classic microbiological methodologies, showing that other microorganisms different from those determined on selective culture media might be the main cause of microbiological spoilage.
Food Microbiology, 2019
Bacterial communities composition using 16S Next Generation Sequencing (NGS) and Volatile Organic... more Bacterial communities composition using 16S Next Generation Sequencing (NGS) and Volatile Organic Compounds (VOCs) profile of whole blue crabs (Callinectes sapidus) stored at 4 and 10°C (proper and abuse temperature) simulating real storage conditions were performed. Conventional microbiological and chemical analyses (Total Volatile Base-Nitrogen/TVB-N and Trimethylamine-Nitrogen/TMA-N) were also carried out. The rejection time point was 10 and 6 days for the whole crabs stored at 4 and 10°C, respectively, as determined by development of unpleasant odors, which coincided with crabs death. Initially, the Aerobic Plate Count (APC) was 4.87 log cfu/g and increased by 3 logs at the rejection time. The 16S NGS analysis of DNA extracted directly from the crab tissue (culture-independent method), showed that the initial microbiota of the blue crab mainly consisted of Candidatus Bacilloplasma, while potential pathogens e.g. Listeria monocytogenes, Pseudomonas aeruginosa and Acinetobacter baumannii, were also found. At the rejection point, bacteria of Rhodobacteraceae family (52%) and Vibrio spp. (40.2%) dominated at 4 and 10°C, respectively. TVB-N and TMA-N also increased, reaching higher values at higher storage temperature. The relative concentrations of some VOCs such as 1-octen-3-ol, trans-2-octenal, trans,trans-2,4-heptadienal, 2-butanone, 3-butanone, 2-heptanone, ethyl isobutyrate, ethyl acetate, ethyl-2-methylbutyrate, ethyl isovalerate, hexanoic acid ethyl ester and indole, exhibited an increasing trend during crab storage, making them promising spoilage markers. The composition of microbial communities at different storage temperatures was examined by 16S amplicon meta-barcoding analysis. This kind of analysis in conjugation with the volatile profile can be used to explore the microbiological quality and further assist towards the application of the appropriate strategies to extend crab shelf-life and protect consumer's health.
John Wiley & Sons, Ltd eBooks, Nov 30, 2013
Demand for seafood has consistently increased during recent years with fish protein being the maj... more Demand for seafood has consistently increased during recent years with fish protein being the major animal protein consumed in many parts of the world. According to the Food and Agriculture Organization (FAO, 2012), fresh seafood represents 40.5% of the world's seafood production, while processed products (frozen, cured, canned, etc.) represent 45.9%. To assure the quality of raw material used for processing, fish has to be treated carefully before and after harvest. Often fish and shellfish undergo some type of handling or primary processing (washing, gutting, filleting, shucking, etc.), before the main processing occurs, to assure their quality and safety, as well as to produce new, convenient and added-value products (e.g. packed fish fillets instead of unpacked, whole ungutted fish). Processing of seafood mainly inhibits and/or inactivates bacteria and enzymes which results in shelf-life extension and also assures food safety. While the main role of processing is preservation, processing not only extends shelf life but also creates a new range of products. Seafood processing uses almost all the processing methods available to the food industry. The most widely used methods to preserve fish involve the application of low temperatures (chilling, super-chilling, freezing). Improvements in packaging technology (modified atmosphere packaging, MAP) and the application of chilling maximise quality retention as well as extending shelf life. Heating inactivates bacterial pathogens and spoilage microorganisms, which contributes to the stability and safety of the products. Irradiation is a well-established, non-thermal method, while high-pressure processing of
Sustainability
The aquatic environment is a reservoir of many species that have not yet been exploited at a glob... more The aquatic environment is a reservoir of many species that have not yet been exploited at a global level and have not been extensively investigated. The aim of the present work was to study the microbial populations, the bacterial communities and physicochemical parameters (pH, water activity, humidity, salinity) in raw, frozen, boiled, dehydrated and salted final products of two sea cucumber species (Holothuria polii and Holothuria tubulosa) originating from the Hellenic seawaters. The results indicated that all products were found at acceptable levels from a microbiological point of view. The metabarcoding analysis of the 16S rRNA gene revealed the existence of several different bacterial groups, the presence and abundance of which were mainly dependent on product type, even though some moderate differences in the microbiota profile between the two sea cucumber species were also detected in some of the products. Overall, the present work deals with an underexplored aquatic produc...
Journal of the Science of Food and Agriculture, Nov 11, 2013
BACKGROUND: An increasing interest in snail farming in Greece and other European countries has be... more BACKGROUND: An increasing interest in snail farming in Greece and other European countries has been observed. Despite the fact that edible snails have been involved with problems of Salmonella spp. contamination, there are to our knowledge only limited studies regarding microbiological safety and hygiene of such products. Enumeration of microbial populations and presence/absence of Salmonella spp. in snail meat and intestines of wild Cornu aspersum, Helix lucorum and cultured Cornu aspersum snails from indoor/outdoor type farms was conducted. Furthermore, snail-processing steps were simulated in the laboratory and the population reduction in snail meat was determined. RESULTS: Microbial populations were higher in intestines than snail meat in almost all cases. Escherichia coli/coliforms and Enterococcus spp. populations were lower in the intestines and snail meat of cultured C. aspersum. Salmonella spp. were detected in the intestines and snail meat of wild snails only. The high levels of bacterial populations were considerably reduced after the appropriate processing. CONCLUSION: The lower populations of E. coli/coliforms, Enterococcus spp. and especially the absence of Salmonella spp. in cultured snails show that the controlled conditions decrease the possibility of pathogen presence and contribute to food safety and public health.
Elsevier eBooks, 2017
Fresh and minimally processed fish and seafood spoil due to the action of a consortium of microor... more Fresh and minimally processed fish and seafood spoil due to the action of a consortium of microorganisms, the so-called specific spoilage organisms (SSOs) that have the ability to dominate and produce metabolites that directly affect the sensory properties of the product, resulting in its rejection by the consumers. The selection of SSOs is affected by fish origination, processing, and storage conditions and various implicit factors such as antagonism for nutrients and microbial interactions. The metabolic products of SSOs causing the spoilage are various volatile compounds that mainly come from the assimilation of nonprotein-nitrogen of fish flesh. Qualitative and quantitative determination of SSOs is of great interest, and current molecular techniques provide us with powerful tools for exploring the diversity and dynamics of SSOs. The inhibition of SSOs by applying appropriate preservation strategies can retain fish freshness and extend shelf life. Elucidation of SSOs’ metabolic potential and activity and the estimation of the growth and population level provide us with tools for rapid evaluation of fish freshness/spoilage status and remaining shelf life.
International Journal of Food Microbiology, Aug 1, 1998
The ability of heat injury to confer sensitivity to nisin in a Gram negative pathogen was investi... more The ability of heat injury to confer sensitivity to nisin in a Gram negative pathogen was investigated. Injury and inactivation kinetics of Salmonella enteritidis PT4 in the presence of nisin were determined in media, liquid whole egg and egg white using cultural methods and capacitance monitoring to detect injury. Addition of nisin in concentrations from 500 IU / ml to 2500 IU / ml in the heating menstruum caused a reduction of required pasteurisation time of up to 35%, principally as a result of its effect on cells suffering damage during heating. In egg white and liquid whole egg the organism's heat susceptibility was greater than in nutrient broth, particularly in egg white which contained no fat and had an alkaline pH. The effect of nisin on heat susceptibility was however less pronounced than in nutrient broth due to its interaction with protein and fat. Though nisin did not enhance the lethality of heat processes, injury is more severe in egg white containing nisin, presumably as a result of its interaction with antimicrobial factors in egg white.
Letters in Applied Microbiology, Sep 1, 2000
Rapid chilling in the presence of nisin caused a dose-dependent reduction in the populations of s... more Rapid chilling in the presence of nisin caused a dose-dependent reduction in the populations of several Gram-negative bacteria, despite the fact that appreciable structural injury to the outer membrane was not detected. Pseudomonas aeruginosa was most affected, followed by Pseudomonas fragi, Salmonella enteritidis PT4, PT7 and Escherichia coli, respectively. Addition of nisin after the chilling treatment had no effect. The results are ascribed to a transient susceptibility caused by phase changes in the lipids associated with the outer membrane, which are rapidly reversed when the cells return to higher temperatures. Combinations of chilling shock, nisin and EDTA gave much lower reductions of Salmonella and Pseudomonas on chicken skin in comparison with broths. This is attributed to a buffering of the temperature shock experienced by adherent bacteria and binding of the nisin by food particles.
Food Microbiology, 2005
Green-table olives, unheated and pasteurized, of Greek cultivar Conservolea were supplemented wit... more Green-table olives, unheated and pasteurized, of Greek cultivar Conservolea were supplemented with glucose or sucrose in various amounts inoculated with Lactobacillus plantarum and fermentation was conducted. Although sugar supplements did not affect the lactic acid bacteria growth rate, they increased the rate of pH drop and the production of acids and lowered the final pH values in all cases. Adequate supplements of sugars (0.5%, 1.0% w v À1), of both types, in unheated olive fermentation, resulted in a fast pH drop, causing a satisfactory halt of Enterobacteriaceae growth in the first days of fermentation, and a subsequent population decline occurred in the following days, eliminating the danger of early stage spoilage and ensuring the safety of the final product. In pasteurized olives, where L. plantarum starter was the only microbial flora, it was considered worth evaluating the fermentation progress without any competition. The rate of pH drop was not as high as in unheated olives, but final pH values and acid development were more pronounced. Lactic acid was the predominant acid developed in both unheated and pasteurized olive fermentation, and increased sugar supplements resulted in faster production and higher yields of this acid. Acetic acid was also produced in low amounts at the end of fermentation, except in the cases of pasteurized olive fermentation supplemented with sucrose, where acetic acid was absent. A switch from homo-fermentative to hetero-fermentative metabolism might have taken place in case of glucose presence, but the same was not observed for sucrose.
Journal of the Science of Food and Agriculture, Nov 7, 2014
BACKGROUND: Sea bream fillets are one of the most important value-added products of the seafood m... more BACKGROUND: Sea bream fillets are one of the most important value-added products of the seafood market. Fresh seafood spoils mainly owing to bacterial action. In this study an exploration of initial and spoilage microbiota of sea bream fillets stored under air and commercial modified atmosphere packaging (MAP) at 0 and 5 ∘ C was conducted by 16S rRNA gene sequence analysis of isolates grown on plates. Sensory evaluation and enumeration of total viable counts and spoilage microorganisms were also conducted to determine shelf life and bacterial growth respectively. RESULTS: Different temperatures and atmospheres affected growth and synthesis of spoilage microbiota as well as shelf life. Shelf life under air at 0 and 5 ∘ C was 14 and 5 days respectively, while under MAP it was 20 and 8 days respectively. Initial microbiota were dominated by Pseudomonas fluorescens, Psychrobacter and Macrococcus caseolyticus. Different temperatures and atmospheres affected the synthesis of spoilage microbiota. At the end of shelf life, different phylotypes of Pseudomonas closely related to Pseudomonas fragi were found to dominate in most cases, while Pseudomonas veronii dominated in fillets under MAP at 0 ∘ C. Furthermore, in fillets under MAP at 5 ∘ C, new dominant species such as Carnobacterium maltaromaticum, Carnobacterium divergens and Vagococcus fluvialis were revealed. CONCLUSION: Different temperature and atmospheric conditions affected bacterial growth, shelf life and the synthesis of spoilage microbiota. Molecular identification revealed species and strains of microorganisms that have not been reported before for sea bream fillets stored under various conditions, thus providing valuable information regarding microbiological spoilage.
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Papers by Ioannis Boziaris