References of "Daube, Georges"
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See detailBacteriological assessment of smoked game meat in Lubumbashi, D.R.C.
Kabwang a Mpalang, Rosette; Kakubu a Mpalang, Mireille; Mukeng Kaut, Clarence et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2013), 17

The bacteriological quality of smoked game meat in Lubumbashi has not been studied much to date. The present study focused on the analysis of 182 samples of smoked game meat from three species, Syncerus ... [more ▼]

The bacteriological quality of smoked game meat in Lubumbashi has not been studied much to date. The present study focused on the analysis of 182 samples of smoked game meat from three species, Syncerus caffer (n = 63), Phacochoerus aethiopicus (n = 60) and Sylvicapra grimmia (n = 59), sold at retail outlets in Lubumbashi. The isolation of Escherichia coli from 81.3% of samples (mean 4.87 ± 0.6 log10 CFU.g-1 of sample) confirms significant faecal contamination of smoked game meat. The study has determined by culture prevalences of 0.0%, 4.3% [CI95% 1.4-7.4], 3.8% [CI95% 1.1-6.6] and 14.2% [CI95% 9.2-19.4] respectively for Shiga toxigenic Escherichia coli (STEC), Salmonella spp., Campylobacter jejuni and Campylobacter coli. Using Polymerase Chain Reaction, these prevalences were of 2.2% [IC95% 0.1-4.3], 6.0% [IC95% 2.6-9.5], 3.8% [IC95% 1.1-6.6] and 15.9% [IC95% 10.6-21.3] respectively for STEC, Salmonella spp., C. jejuni and C. coli. Syncerus caffer was established as a potential vehicle of STEC carrying stx1 gene (3.2%), stx2 gene (1.6%) and the combination of stx2 and eae genes (1.6%). On the basis of these data, we suggested the need for developing monitoring plans of the production, preparation, handling and distribution of smoked game meat in Lubumbashi. [less ▲]

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See detailMicrobiological and Physico-Chemical Quality of Smoked Shrimp, An Expanding Food Condiment in Beninese Local Markets
Kpoclou, Euloge Y.; Anihouvi, Victor B.; Azokpota, Paulin et al

in Food and Public Health (2013), 3(6), 277-283

Entire Smoked Shrimp (ESS) and Smoked Shrimp Powder (SSP) are two food condiments widely used in Beninese local cooking practices. Twelve samples of each product collected from local markets were ... [more ▼]

Entire Smoked Shrimp (ESS) and Smoked Shrimp Powder (SSP) are two food condiments widely used in Beninese local cooking practices. Twelve samples of each product collected from local markets were evaluated for safety assessment using standard methods. Regarding the microbiological status of the samples, the Enterobacteriaceae were detected in 83% and 75% of ESS and SSP respectively, whereas 25% of samples of each product were found to contain E. coli. Pathogenic bacteria such as S. aureus and Salmonella were absent. Except 8% and 17% of SSP sample exceeding the maximal limit of 106 UFC/g for Aerobic Mesophilic Bacteria and 104 UFC/g Enterobacteriaceae respectively, all the other samples were within the acceptable limits. Water activity values were low, ranging between 0.54±0.01 for SSP and 0.61±0.01 for ESS, showing a potential microbial stability. Considering the chemical hazards, 15 EU priority polycyclic aromatic hydrocarbon (PAHs) were detected in the samples examined with median Benzo(a) pyrene and PAH4 contents (91 μg kg-1 and 490 μg kg-1respectively) exceeding the European maximal limit (5.0 μg kg-1 and 30 μg kg-1). This study showed that smoked shrimps may be generally safe from a microbiological point of view, but they constitute a large source of exposure to possible carcinogenic PAHs. [less ▲]

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See detailGenetic and evolutionary perspectives on genogroup III, genotype 2 bovine noroviruses
Mauroy, Axel ULg; Scipioni, Alexandra; Mathijs, Elisabeth et al

in Archives of Virology (2013)

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See detailPresence of Clostridium difficile in pigs and cattle intestinal contents and carcass contamination at the slaughterhouse in Belgium.
Rodriguez Diaz, Cristina ULg; Avesani, V.; Van Broeck, J. et al

in International Journal of Food Microbiology (2013), 166(2), 256-262

The objective of this study was to evaluate the presence of Clostridium difficile in intestinal and carcass samples collected from pigs and cattle at a single slaughterhouse. C. difficile was isolated in ... [more ▼]

The objective of this study was to evaluate the presence of Clostridium difficile in intestinal and carcass samples collected from pigs and cattle at a single slaughterhouse. C. difficile was isolated in 1% and 9.9% of the pig and cattle intestinal contents and in 7.9% and 7% of cattle and pig carcass samples respectively. A total of 19 different PCR-ribotypes were identified, among them types 078 and 014. Seven of 19 ribotypes correlated with the PCR-ribotypes involved in human C. difficile infections in Belgium. This study confirms that animals are carriers of C. difficile at slaughter and ribotypes are identical than those in humans, and that carcass contamination occurs inside the slaughterhouse. [less ▲]

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See detailAntimicrobial Resistance in the food chain: a review
Verraes, Claire; Van Boxtael, Sigrid; Van Meervenne, Eva et al

in International Journal of Environmental Research and Public Health (2013), 10

Antimicrobial resistant zoonotic pathogens present on food constitute a direct risk to public health. Antimicrobial resistance genes in commensal or pathogenic strains form an indirect risk to public ... [more ▼]

Antimicrobial resistant zoonotic pathogens present on food constitute a direct risk to public health. Antimicrobial resistance genes in commensal or pathogenic strains form an indirect risk to public health, as they increase the gene pool from which pathogenic bacteria can pick up resistance traits. Food can be contaminated with antimicrobial resistant bacteria and/or antimicrobial resistance genes in several ways. A first way is the presence of antibiotic resistant bacteria on food selected by the use of antibiotics during agricultural production. A second route is the possible presence of resistance genes in bacteria that are intentionally added during the processing of food (starter cultures, probiotics, bioconserving microorganisms and bacteriophages). A last way is through cross-contamination with antimicrobial resistant bacteria during food processing. Raw food products can be consumed without having undergone prior processing or preservation and therefore hold a substantial risk for transfer of antimicrobial resistance to humans, as the eventually present resistant bacteria are not killed. As a consequence, transfer of antimicrobial resistance genes between bacteria after ingestion by humans may occur. Under minimal processing or preservation treatment conditions, sublethally damaged or stressed cells can be maintained in the food, inducing antimicrobial resistance build-up and enhancing the risk of resistance transfer. Food processes that kill bacteria in food products, decrease the risk of transmission of antimicrobial resistance. [less ▲]

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See detailMicrobial characterization of probiotics-Advisory report of the Working Group "8651 Probiotics" of the Belgian Superior Health Council (SHC).
Huys, Geert; Botteldoorn, Nadine; Delvigne, Frank ULg et al

in Molecular Nutrition & Food Research (2013)

When ingested in sufficient numbers, probiotics are expected to confer one or more proven health benefits on the consumer. Theoretically, the effectiveness of a probiotic food product is the sum of its ... [more ▼]

When ingested in sufficient numbers, probiotics are expected to confer one or more proven health benefits on the consumer. Theoretically, the effectiveness of a probiotic food product is the sum of its microbial quality and its functional potential. Whereas the latter may vary much with the body (target) site, delivery mode, human target population, and health benefit envisaged microbial assessment of the probiotic product quality is more straightforward. The range of stakeholders that need to be informed on probiotic quality assessments is extremely broad, including academics, food and biotherapeutic industries, healthcare professionals, competent authorities, consumers, and professional press. In view of the rapidly expanding knowledge on this subject, the Belgian Superior Health Council installed Working Group "8651 Probiotics" to review the state of knowledge regarding the methodologies that make it possible to characterize strains and products with purported probiotic activity. This advisory report covers three main steps in the microbial quality assessment process, i.e. (i) correct species identification and strain-specific typing of bacterial and yeast strains used in probiotic applications, (ii) safety assessment of probiotic strains used for human consumption, and (iii) quality of the final probiotic product in terms of its microbial composition, concentration, stability, authenticity, and labeling. [less ▲]

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See detailRaw or heated cow milk consumption: Review of risks and benefits
Claeys, W. L.; Cardoen, S.; Daube, Georges ULg et al

in Food Control (2013), 31(1), 251-262

In the context of the prevailing trend toward more natural products, there seems to be an increasing preference for raw milk consumption as raw milk is associated with several perceived health benefits ... [more ▼]

In the context of the prevailing trend toward more natural products, there seems to be an increasing preference for raw milk consumption as raw milk is associated with several perceived health benefits that are believed to be destroyed upon heating. However, many human pathogens can be isolated from raw cow milk. The prevalence of foodborne pathogens in raw cow milk varies, but their presence has been demonstrated in many surveys and foodborne infections have been repeatedly reported for Campylobacter, Salmonella spp. and human pathogenic verocytotoxin-producing Escherichia coli. In industrialized countries, milk-borne and milk product-borne outbreaks represent 2-6% of the bacterial foodborne outbreaks.The aim of this review is to present scientifically sound data regarding the risks and benefits related to the consumption of raw and heated cow milk. Both microbiological aspects (e.g., the prevalence of milk-borne pathogens, pathogen growth inhibition by antimicrobial systems and by lactic acid producing bacteria, probiotic bacteria, etc.) and nutritional or health aspects (nutritional value, immunity, allergies, lactose intolerance, diabetes, milk digestibility, etc.) are considered.As such, it is demonstrated that consumption of raw milk poses a realistic health threat due to a possible contamination with human pathogens. It is therefore strongly recommended that milk should be heated before consumption. With the exception of an altered organoleptic profile, heating (in particularly ultra high temperature and similar treatments) will not substantially change the nutritional value of raw milk or other benefits associated with raw milk consumption. © 2012 Elsevier Ltd. [less ▲]

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See detailClostridium difficile in young farm animals and slaughter animals in Belgium
Rodriguez Diaz, Cristina ULg; Taminiau, Bernard ULg; Vandebroek, Johan et al

in Anaerobe (2012), 18(6), 621-625

Faecal carriage of Clostridium difficile in healthy animals has been reported recently, especially in piglets and calves. However there is limited data about carriage in animals just prior to slaughter in ... [more ▼]

Faecal carriage of Clostridium difficile in healthy animals has been reported recently, especially in piglets and calves. However there is limited data about carriage in animals just prior to slaughter in Europe. The main objective of this study was to determine the presence of C. difficile in pigs and cattle at the slaughterhouse. C. difficile was isolated in 6.9% of the cattle at the slaughterhouse. None of the pig slaughter samples were positive for C. difficile after an enrichment time of 72 h. For complementary data, a short study was conducted in piglets and calves at farms. C. difficile was more prevalent in piglets (78.3%) than in calves (22.2%) on the farms. Regarding the piglet samples, 27.8% of the positive samples were detected without enrichment of stools. The PCR ribotype 078 was predominant in farm animals. Samples isolated from slaughter cattle presented the widest range in PCR-ribotype variety, and the most prevalent PCR ribotype was 118a UCL. The results of this study confirm that C. difficile is present in slaughter animals in Belgium with a large percentage of toxigenic strains also commonly found in humans. [less ▲]

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See detailRetrospective Analysis of a Listeria monocytogenes Contamination Episode in Raw Milk Goat Cheese Using Quantitative Microbial Risk Assessment tools
Delhalle, Laurent ULg; Ellouze, Mariem; Yde, Marc et al

in Journal of Food Protection (2012), 75(12), 2122-2135

In 2005, the Belgian authorities reported a Listeria monocytogenes contamination episode in cheese made from raw goat's milk. The presence of an asymptomatic shedder goat in the herd caused this ... [more ▼]

In 2005, the Belgian authorities reported a Listeria monocytogenes contamination episode in cheese made from raw goat's milk. The presence of an asymptomatic shedder goat in the herd caused this contamination. On the basis of data collected at the time of the episode, a retrospective study was performed using an exposure assessment model covering the production chain from the milking of goats up to delivery of cheese to the market. Predictive microbiology models were used to simulate the growth of L. monocytogenes during the cheese process in relation with temperature, pH, and water activity. The model showed significant growth of L. monocytogenes during chilling and storage of the milk collected the day before the cheese production (median increase of 2.2 log CFU/ml) and during the addition of starter and rennet to milk (median increase of 1.2 log CFU/ml). The L. <br /><br />monocytogenes concentration in the fresh unripened cheese was estimated to be 3.8 log CFU/g (median). This result is consistent with the number of L. monocytogenes in the fresh cheese (3.6 log CFU/g) reported during the cheese contamination episode. A variance-based method sensitivity analysis identified the most important factors impacting the cheese contamination, <br /><br />and a scenario analysis then evaluated several options for risk mitigation. Thus, by using quantitative microbial risk assessment tools, this study provides reliable information to identify and control critical steps in a local production chain of cheese made from raw goat's milk. [less ▲]

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See detailLa diversité bactérienne et son évolution pendant la conservation de viandes bovines fraîches de différentes origines conditionnées sous vide
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Taminiau, Bernard ULg et al

Poster (2012, December)

Le but de cette étude à été d'évaluer la diversité bactérienne et son évolution pendant la conservation de viandes bovine fraîches sous vide, en fonction de leur origine et du respect ou non d’une ... [more ▼]

Le but de cette étude à été d'évaluer la diversité bactérienne et son évolution pendant la conservation de viandes bovine fraîches sous vide, en fonction de leur origine et du respect ou non d’une température proche du point de congélation. Les dénombrements réalisés ont mis en évidence que les viandes d’origines britannique et belge testées présentent un écosystème microbien différent. Les analyses par approche métagénomique permettront d’éclaircir ces différences, surtout en ce qui concerne la présence de bactéries pouvant jouer un rôle "bioprotecteur" permettant d’améliorer la conservabilité des viandes. [less ▲]

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See detailValidation de la qualité de la viande hachée de porc par une approche métagénomique ciblée
Taminiau, Bernard ULg; Nezer, Carine; Adolphe, Ysabelle ULg et al

Conference (2012, November 13)

Food products represent great biotopes for bacteria. The optimization of foodstuffs conservation pass by a better understanding of those biotopes and their spoilage. The current techniques of new ... [more ▼]

Food products represent great biotopes for bacteria. The optimization of foodstuffs conservation pass by a better understanding of those biotopes and their spoilage. The current techniques of new generation sequencing give a new dimension to the microbial ecology, through the metagenomic analysis of individuals' large number, within a mixed microbial population. Our aim is to demonstrate that this methodology can be successfully applied to the validation of the quality of foodstuffs during storage. This study was carried out on pork minced meat with shelf-life tests in various conditions of preservation (temperature and packaging). The analysis was performed in parallel with standardized microbiological methods and with massive sequencing of two hypervariables regions of the rDNA 16S. The results show an excellent correlation between the two approaches and underline the tremendous utility of metagenomic analysis for in-depth characterization of the potential altering bacteria in fresh meat. [less ▲]

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See detailViandes bovines à longue durée de conservation conditionnées sous vide : isolement et caractérisation de souches de Carnobacterium
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Baptista Rodrigues, Ana Lucia ULg et al

Poster (2012, November 13)

The lactic acid bacteria Carnobacterium divergens and Carnobacterium maltaromaticum are often associated to meat and meat products and may be used as a protective culture, improving the microbial ... [more ▼]

The lactic acid bacteria Carnobacterium divergens and Carnobacterium maltaromaticum are often associated to meat and meat products and may be used as a protective culture, improving the microbial stability and the safety of these products. In this context, the aim of this study was to isolate and characterize Carnobacterium from long shelf-life vacuum-packed beef. LAB counts after culture at +22°C remained below 2.0 log UFC/cm², even at the end of shelf life. On the other hand, the ecosystem evaluation performed by metagenomics revealed the predominance of Carnobacterium and Lactobacillus on the samples. After spreading of a peptone water suspension obtained from the samples on PCA, pure isolates were collected and identified by API 50 CHL galleries. Seventy-eight % of isolates were C. maltaromaticum, 3 % C. divergens and 19 % could not be identified. The next step of this work will consist in performing a genotypic and functional characterization of these Carnobacterium isolates. [less ▲]

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See detailStudy of the microbial flora of freshwater and seawater fish filets in different packaging conditions by metagenomic analysis targeted on the 16S ribosomal DNA
Delhalle, Laurent ULg; Taminiau, Bernard ULg; Nezer, Carine et al

Conference (2012, October 19)

Metagenomics has appeared as a powerful tool to study bacterial composition of various environmental samples. This work describes the application of this technique to study the bacterial population of two ... [more ▼]

Metagenomics has appeared as a powerful tool to study bacterial composition of various environmental samples. This work describes the application of this technique to study the bacterial population of two fresh fish filets. The two fish species are from freshwater (pangasius) and seawater (haddock), respectively. Samples where directly analyzed the day of receipt. Others samples were analyzed at the end their shelf life after storage at 4°C (1/3 of their shelf life) and 8°C (2/3 of their shelf life). For these samples, packagings were made in plastic wrap for atmospheric air condition and in trays under modified atmosphere. Classical microbiological and 16S rDNA metagenomic analysis were carried out on all these samples. The composition and evolution of microbial populations of fish filet stored under different packaging conditions and temperatures of storage were investigated with identification of bacteria species. A total of 40 different species were identified for both fish types. Gram-negative bacteria are always predominated among the initial flora and at the end of the shelf life in all the trials. At the beginning of storage, the predominant Gram-negative microflora consisted of Moraxellaceae (Acinetobacter spp, Psychrobacter spp.), Pseudomonadaceae (Pseudomonas spp), and Shewanella spp and the Gram-positive flora was identified as Lactobacillaceae (Carnobacterium spp), Brochothrix thermosphacta and Planococcus donghaensis (only for pangasius). For the pangasius, Planococcus donghaensis is only present before the fish is packed and its dominant presence could provide an indication of the freshness of the fish. The metagenomic analysis is a useful tool to identify and to measure the relative proportions of bacterial species in fish filet samples. [less ▲]

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See detailL’analyse métagénomique ciblée au service de la microbiologie des aliments : applications concrètes
Taminiau, Bernard ULg; Nezer, Carine; Delhalle, Laurent ULg et al

Conference (2012, September 21)

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See detailEffect of duration and temperature of previous vacuum-packed storage on the microbiological quality of Belgian Blue meat packed in high-oxygen atmosphere
Didimo Imazaki, Pedro Henrique ULg; Tahiri, Assia ULg; Daube, Georges ULg et al

Poster (2012, September 05)

The aim of this experiment was to study the effect of duration and temperature of previous vacuum-packed (VP) storage on the microbiological quality of Belgian Blue (BB) beef packed in high-oxygen ... [more ▼]

The aim of this experiment was to study the effect of duration and temperature of previous vacuum-packed (VP) storage on the microbiological quality of Belgian Blue (BB) beef packed in high-oxygen atmosphere. VP striploins from bulls (B) and cows (C) were stored at −1 °C and +4 °C for up to 80 days. These meats were subsequently repackaged under modified atmosphere (MA) – 70 % O2/30 % CO2 – at different times, and stored 2 d at +4 °C and 5 d at +8 °C. The average initial counts in VP meats were 3.6 log CFU/cm² (B) and 2.7 log CFU/cm² (C) for total viable count (TVC) at +22 °C; < 2.0 log CFU/cm² (B and C) for lactic ac id bacteria (LAB) at +22 °C; 1.1 log CFU/cm² (B) and 1.3 log CFU/cm² (C) for Enterobacteriaceae at +30 °C and < 1.0 log CFU/cm² (B and C) for Pseudomonas spp. and Brochothrix thermosphacta. During the first 40 days of VP storage, temperature had a striking influence on microbial growth. The maximum count differences between storage temperatures were obtained at the 20th day of storage: 2.7 log CFU/cm² (B) and 2.9 log CFU/cm² (C) for TVC, 4.0 log CFU/cm² (B and C) for LAB and 3.6 log CFU/cm² (B and C) for Enterobacteriaceae. The difference in TVC between temperatures at the 20th day tended to disappear once the meats were repacked under MA and stored during seven days. Conversely, the difference in LAB and Enterobacteriaceae counts tended to be maintained after MA repackaging, showing that duration and temperature of VP storage had influence on microbiological quality of BB meat subsequently stored in high-oxygen atmosphere. Moreover, chilling at temperatures very close to the freezing point of meat during VP storage, which has already showed innumerous advantages for physicochemical quality of meat, was capital to maintain the microbiological quality of BB fresh meat during subsequent MA-packed storage. [less ▲]

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See detailMetagenomic analysis as a tool to better characterize the bacterial content of food and food preparations.
Taminiau, Bernard ULg; Delhalle, Laurent ULg; Nezer, Carine et al

Conference (2012, September 04)

Metagenomic analysis is a new culture-independent approach for assigning a taxonomic, genic or functional identity to bacterial DNA fragments of unknown origin. Its power and utility is increasingly ... [more ▼]

Metagenomic analysis is a new culture-independent approach for assigning a taxonomic, genic or functional identity to bacterial DNA fragments of unknown origin. Its power and utility is increasingly rising thanks to the next generation sequencing techniques. It is now mature and cheap enough to be transposed to more applied fields like the food microbiology. We demonstrated in several studies the extraordinary potential of the targeted metagenomic analysis to different problematics related to food products. First, this approach is highly useful for the validation of the shelf life of food products. We analyzed standardized pork minced meat and meat product samples packaged either under modified atmosphere (MAP - 30% CO2, 70% O2) or under permeable atmosphere packaging, stored at different temperature (4°C, 4-8°C and 12°C) until the end of shelf-life. The metagenomic analysis allowed to identify species of all the sub-dominant bacterial populations. This approach showed why MAP can improve meat quality by favoring certain species rather than others. As a second example, we sought to identify the potential spoiling bacteria in several food products like raw fish, rind cheese or vacuum packed beef meats in order to illustrate the usefulness of metagenomics for the quality control of food preparations. Samples from various food matrices were screened to identify the bacterial contaminants. We combined the bioinformatics analysis with a classical approach to generate effective quantitative data for the various bacterial populations detected. This analysis characterizes the samples both on the identity of the potential spoiling bacteria present and on the quantification level of the contaminants. Finally, the metagenomic analysis reveals the presence of numerous uncultured and uncharacterized bacteria. The use of a carefully designed analysis pipeline has been used to ensure to label the bacterial population with a precise taxonomic identity and to determine whether the targeted population corresponds to a known species or not. This way, even if the nearest known homologous sequence is an environmental sample, its relatedness to known species can be deduced. This represents a new tool to trace yet uncharacterized food spoiling bacteria. [less ▲]

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See detailMolecular identification of the bacterial populations of steak tartare, a raw consumed meat preparation: a practical use of targeted metagenomic analysis
Taminiau, Bernard ULg; Delhalle, Laurent ULg; Nezer, Carine et al

Poster (2012, September 04)

Steak tartare is a popular meat dish in Belgium and other european countries. It is often consumed with french fries or as sandwich spread. This product, due to its raw nature, is highly sensitive to ... [more ▼]

Steak tartare is a popular meat dish in Belgium and other european countries. It is often consumed with french fries or as sandwich spread. This product, due to its raw nature, is highly sensitive to bacterial alteration. A better understanding of the bacterial content of this meat product will thus be insightful to master the alteration hazards. Throughout a targeted metagenomic analysis we characterized the bacterial populations of several steak tartare samples. These samples were bought and analyzed during the same day, from three different commercial sources: butchery, sandwich vendor and restaurant. A classic microbiological analysis was performed in parallel. The metagenomic analysis was targeted on two different hypervariable regions of the bacterial 16S rDNA, in order to compare the bacterial identification efficiency. A total of 60,500 sequences for 12 samples were submitted to a metagenomic analysis. The best hypervariable region enabled us to identify 356 different bacterial species. Lactobacillus algidus is the leading bacterial species, representing 52% of the total analyzed sequences, followed by an uncultured Pseudomonas sp. (8.43%) and Photobacterium phosphoreum (7.92%). The analysis of the results shows that remarkable differences appear between the three sources of steak tartare. First, the samples from the butchery are mainly composed of Lactobacillus populations and to a lesser extend of environmental contaminants like Xanthomonas campestris. On the opposite, the samples from the restaurant are contaminated with higher level of Leuconostocaceae like Leuconostoc carnosum or an uncultured Weissella sp., or with gamma-proteobacteria like Pseudomonas sp. or Psychrobacter sp. These last samples were characterized with some alteration (slime, off odor) that can thus be put in relation with the bacterial populations identified. Combining a broad-range sequencing effort to a rigorous computer analysis gives a powerful tool for the microbiology of food products. Its application can be virtually extended to every food product be readily transposed to the food industry. [less ▲]

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See detailThe extraordinary potential of metagenomic tools for food microbiology: an example with bacterial microbiota of raw and pasteurized milk cheeses
Delhalle, Laurent ULg; Nezer, Carine; Taminiau, Bernard ULg et al

Poster (2012, September 03)

Among the culture-independent techniques, ultra-sequencing has contributed to place metagenomic analysis as the best alternative to study complex microbiota. During the last three years, metagenomic ... [more ▼]

Among the culture-independent techniques, ultra-sequencing has contributed to place metagenomic analysis as the best alternative to study complex microbiota. During the last three years, metagenomic studies were used essentially for environmental samples but it could be used also to analyse bacterial populations of food samples. This work describes the application of this technique to study the bacterial population of different types of soft cheeses. Among these, three of them are a typical Belgian soft cheese with washed rind (two with raw milk and the third with pasteurized milk). The fourth is a French creamy soft cheese made with raw milk. Classical microbiological and 16S rDNA metagenomic analysis were carried out in the core and on the rind of the four cheeses, giving a total of 8 samples. In total, 48 genus and 163 species were identified for all samples. As expected Lactoccocus lactis and/or cremoris are the most representative species in the core of the four cheeses. On the rind of cheeses, the predominant bacterial species are Psychrobacter glacinola, Staphylococcus equorum, Corynebacterium casei and Marinilactibacillus psychrotolerans. Brevibacterium spp and Psychroflexus spp are important for the rind of washed rind cheeses. All these species are present in different proportions following the origin and the cheese making process and they are well known for their organoleptic properties on the rind of cheese. The two Belgian soft cheese made with raw milk are composed of many more different bacterial species. While the cheese made from pasteurized milk contains less species mainly composed by Lactococcus lactis (97,6%) in the core. An unexpected result is the low diversity of the a French creamy soft cheese made with raw milk with only two predominent species : Lactoccocus cremoris and Leuconostoc citreum are present in the core (94,9% and 4,9% , respectively) and on the rind (93,8% and 5% , respectively). Compared with the other cheeses made with raw milk, this result is surprising. The bacterial cheese microbiota plays a central role in cheese-making. The subtleties of cheese character, as well as their shelf-life, are largely determined by the evolution of their microbiota. [less ▲]

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See detailA new approach of food microbiology with the metagenomic tools: an application on fish
Delhalle, Laurent ULg; Taminiau, Bernard ULg; Nezer, Carine et al

Poster (2012, September 03)

Metagenomics has appeared as a powerful tool to study bacterial composition of various environmental samples. Its interest has started to appear in food microbiology but only on the study of very ... [more ▼]

Metagenomics has appeared as a powerful tool to study bacterial composition of various environmental samples. Its interest has started to appear in food microbiology but only on the study of very particular bacterial populations of fermented food. This work describes the application of this technique to study the bacterial population of two fresh fish filets. The two fish species are from freshwater (pangasius) and seawater (haddock), respectively. Samples where directly analyzed the day of receipt. Others samples were analyzed at the end their shelf life after storage at 4°C (1/3 of their shelf life) and 8°C (2/3 of their shelf life). For these samples, packagings were made in plastic wrap for atmospheric air condition and in trays under modified atmosphere. Classical microbiological and 16S rDNA metagenomic analysis were carried out on all these samples. The composition and evolution of microbial populations of fish filet stored under different packaging conditions and temperatures of storage were investigated with identification of bacteria species. A total of 40 different species were identified for both fish types. Gram-negative bacteria are always predominated among the initial flora and at the end of the shelf life in all the trials. At the beginning of storage, the predominant Gram-negative microflora consisted of Moraxellaceae (Acinetobacter spp, Psychrobacter spp.), Pseudomonadaceae (Pseudomonas spp), and Shewanella spp and the Gram-positive flora was identified as Lactobacillaceae (Carnobacterium spp), Brochothrix thermosphacta and Planococcus donghaensis (only for pangasius). Regardless the packaging and the fish origin, significant variations of the initial flora were noted. The important growth of some Gram negative populations could indicate a risk of spoilage. Thus, the metagenomic approach could be used to adequately determine the duration of shelf-life. For the pangasius, Planococcus donghaensis is only present before the fish is packed and its dominant presence could provide an indication of the freshness of the fish. The metagenomic analysis is a useful tool to identify and to measure the relative proportions of bacterial species in fish filet samples. [less ▲]

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See detailLes modèles de microbiologie prévisionellepour la maitrise de la sécurité des aliments (synthèse bibliographique)
Delhalle, Laurent ULg; Daube, Georges ULg; Adolphe, Ysabelle ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(3), 369-381

Predictive microbiology aims to predict the evolution of microorganisms in foods with mathematical models. Several models have been published and the complexity of some of them makes their use difficult ... [more ▼]

Predictive microbiology aims to predict the evolution of microorganisms in foods with mathematical models. Several models have been published and the complexity of some of them makes their use difficult for the uninitiated. However, the use of this discipline will become widespread in coming years. These models provide, for example, additional tools to ensure the microbiological safety of food, to establish the contamination flow in a food chain, to develop and to assist the quality assurance systems. The development of new computer software and database will enable stakeholders in the food chain to have a better control of microbiological hazards. The aim of this summary is to give an overview of existing models of predictive microbiology and their applications. A first approach of the primary, secondary and tertiary models is given. The modelling of latency, integrated models and growth tests are also discussed. [less ▲]

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