Biomedical subjects

J Debevere

Publications and source records attributed to J Debevere.

At least 19 recordsLinked to original sources

PubMed2003

Relation between microbiological quality, metabolite production and sensory quality of equilibrium modified atmosphere packaged fresh-cut produce.

The quality of four types of fresh-cut produce, packaged in consumer-sized packages under an equilibrium modified atmosphere and stored at 7 degrees C, was assessed by establishing the relation between the microbial outgrowth and the corresponding production of nonvolatile compounds and related sensory disorders. In vitro experiments, performed on a lettuce-juice-agar, demonstrated the production of nonvolatile compounds by spoilage causing lactic acid bacteria and Enterobacteriaceae. Pseudomonas fluorescens and yeasts, however, were not able to produce detectable amounts of nonvolatile metabolites. The type of spoilage and quality deterioration in vivo depended on the type of vegetable. Mixed lettuce and chicory endives, leafy tissues, containing naturally low concentrations of sugars, showed a spoilage dominated by Gram-negative microorganisms, which are not producing nonvolatile compounds. Sensory problems were associated with visual properties and the metabolic activity of the plant tissue. Mixed bell peppers and grated celeriac, on the other hand, demonstrated a fast and intense growth of spoilage microorganisms, dominated by lactic acid bacteria and yeasts. This proliferation resulted in detectable levels of organic acids and the rejection by the trained sensory panel was based on the negative perception of the organoleptical properties (off-flavour, odour and taste). The applied microbiological criteria corresponded well with detectable changes in sensory properties and measurable concentrations of nonvolatile compounds, surely in the cases where lactic acid bacteria and yeasts were provoking spoilage. Consequently, the freshness of minimally processed vegetables, sensitive for outgrowth of lactic acid bacteria and yeasts (e.g., carrots, celeriac, bell peppers, mixtures with non-leafy vegetables) can be evaluated via analysis of the produced nonvolatile compounds.

Bacteria↗

PubMed2003

Survival of Campylobacter jejuni strains of different origin in drinking water.

AIMS: The aim of the study was to measure the survival of 19 Campylobacter jejuni strains of different origins, including two reference strains, four poultry-derived isolates, nine human isolates and four water isolates, in sterilized drinking water. METHODS AND RESULTS: Pure cultures of 19 C. jejuni strains were inoculated in sterile drinking water and incubated at 4 degrees C for 64 days. Survival was determined by culturability on both selective (Karmali agar) and non-selective [Columbia blood agar (CBA)] media. Culturability was shown to be strain and origin-dependent. Campylobacter jejuni showed prolonged survival on a non-selective than on a selective medium. CONCLUSIONS: The origin of the strain is a determining factor for the survival of C. jejuni in drinking water at 4 degrees C. Poultry isolates showed a prolonged survival, which could be an indication that these strains could play an important role in the transmission of campylobacteriosis through water. In addition, culture conditions are an important factor for evaluating the survival of C. jejuni in drinking water at 4 degrees C. The non-selective agar (CBA) allowed growth of C. jejuni over a longer period of time than the selective agar (Karmali). Furthermore, an enrichment broth (Bolton) allowed the recovery of all 19 C. jejuni strains during the 64 days of incubation at 4 degrees C. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlighted differences in culturability depending on culture conditions and on strain origin.

Animals↗

PubMed2003

Modelling the individual cell lag phase. Isolating single cells: protocol development.

AIMS: To develop a protocol to isolate single cells in wells of a microtitre plate, having a high certainty of individual cells, combined with a sufficient yield. METHODS AND RESULTS: Single cells were obtained using 1/2 dilution series in microtitre plates. Seventy-two Lactococcus lactis dilution series were checked by plate counting. When the last five columns of the plates were observed, the chance of having one single cell was 80%, while the yield was 75 wells containing cells. A simulation model confirmed these results. This method was compared with the commonly applied method. CONCLUSIONS: This method makes it possible to combine a higher chance of having one cell in a microtitre well with a slightly higher yield. SIGNIFICANCE AND IMPACT OF THE STUDY: A tool is developed to isolate single cells to provide a suitable base for investigating and modelling the individual cell lag phase.

Cell Division↗

PubMed2003

Antimicrobial effect of spices and herbs on Shigella sonnei and Shigella flexneri.

Of 17 spices and herbs tested at 1% (wt/vol) in Mueller-Hinton (MH) agar, only cloves, thyme, oregano, allspice, basil, rosemary, and marjoram showed antimicrobial effects on Shigella. The MICs of thyme, oregano, basil, and rosemary (as determined by the agar dilution method) ranged from 0.5 to 1% (wt/vol) depending on the Shigella strain used. With the use of various combinations of temperatures (12, 22, and 37 degrees C), pHs (5.0, 5.5, and 6.0), and NaCl concentrations (1, 2, 3, and 4%, wt/vol) and the inclusion or exclusion of thyme or basil at 1% (wt/vol) in an MH agar model system, it was established that basil or thyme can contribute to combination processing as a growth-inhibitory factor for Shigella spp. In the presence of basil and thyme, Shigella flexneri did not develop CFU during the 7-day incubation period for, respectively, 14 and 16 of the 18 tested combinations, while growth was noted in the corresponding temperature-pH-NaCl concentration combinations without basil or thyme. A growth-inhibitory effect on Shigella sonnei was also noted. The results of an orientation study involving the addition of basil and thyme to spaghetti sauce prior to autoclaving and S. sonnei inoculation indicated that basil and thyme contributed to the reduction of S. sonnei after 16 days at 12 degrees C but not at 4 degrees C.

Colony Count, Microbial↗

PubMed2002

Predictive modelling for packaging design: equilibrium modified atmosphere packages of fresh-cut vegetables subjected to a simulated distribution chain.

The impact of temperature fluctuations in a simulated cold distribution chain, typical of commercial practice, was investigated on both the microbial and sensorial quality of equilibrium modified atmosphere (EMA) packaged minimally processed vegetables. The internal O2 concentration of the designed packages could be predicted for the different steps of the simulated distribution chain by applying an integrated mathematical system. The internal atmosphere in the packages remained in its aerobic range during storage in the chain due to the application of high permeable packaging films for O2 and CO2. Spoilage microorganisms were proliferating fast on minimally processed bell peppers and lettuce. Yeasts showed to be the shelf-life limiting group. Visual properties limited the sensorial shelf-life. Listeria monocytogenes was able to multiply on cucumber slices, survived on minimally processed lettuce and decreased in number on bell peppers due to the combination of low pH and refrigeration. Aeromonas caviae was multiplying on both cucumber slices and mixed lettuce, but was as well inhibited by the low pH of bell peppers. Storage temperature control was found to be of paramount importance for the microbial (spoilage and safety) and sensorial quality evaluation of EMA-packaged minimally processed vegetables.

Bacteria↗

PubMed2002

Isolation and characterization of enterohaemorrhagic Escherichia coli O157:1H7 from cattle in Belgium and Poland.

EHEC O157 were isolated from faeces of Belgian and Polish beef slaughter cattle. In Belgium, 1281 faecal samples were analysed by immunomagnetic separation [IMS] after enrichment in buffered peptone water from June 1998 till July 1999. Eighty-one samples (6.3%) were positive for E. coli O157. Phage type 8 was most frequently found. Bulls between 1 and 2 years old, slaughtered in September and October were most frequently found positive. Atypical biochemical features were observed in some isolates: 22 (27%) isolates were urease positive and 1 (1.2%) isolate was unable to ferment lactose. In Poland, 551 faecal samples, taken from January 1999 till December 1999, were examined using exactly the same techniques. Four faecal samples (0.7%) were positive for O157 EHEC, yielding seven phage type 8 isolates. All positive samples were from cattle younger than 2 years. Positive samples occurred in August, September and October.

Animals↗

PubMed2002

Acid tolerance of Shigella sonnei and Shigella flexneri.

AIMS: Determination of the behaviour of Shigella sonnei and Sh. flexneri under acid conditions. METHODS AND RESULTS: The growth and survival of Shigella spp. (9 isolates) in acidified Brain Heart Infusion (BHI) (pH 5.0-3.25 with pH intervals of 0.25) was determined after 6, 24 and 30 h incubation at 37 degrees C. Subsequently, survival of shigellae was studied in apple juice and tomato juice stored at 7 degrees C and 22 degrees C for up to 14 days and in strawberries and a fresh fruit salad, kept at 4 degrees C for 4 and 48 h. CONCLUSIONS: The minimum pH for growth in acidified BHI for Sh. flexneri and Sh. sonnei was, respectively, pH 4.75 and pH 4.50. Survival in fruit juices and fresh fruits depended upon their pH, the type of strain and the incubation temperature. Shigella spp. Survived for up to 14 days in tomato juice and apple juice stored at 7 degrees C. The shortest survival time (2-8 d) was observed in apple juice at 22 degrees C. Sh. sonnei but not Sh. flexneri was recovered after 48 h from strawberries and fruit salad kept at 4 degrees C. SIGNIFICANCE AND IMPACT OF THE STUDY: Acid foods, especially if kept at refrigeration temperatures, support survival of Shigella spp. and may cause Shigella food poisoning.

Beverages↗

PubMed2002

Effectiveness of some recent antimicrobial packaging concepts.

A new type of active packaging is the combination of food-packaging materials with antimicrobial substances to control microbial surface contamination of foods. For both migrating and non-migrating antimicrobial materials, intensive contact between the food product and packaging material is required and therefore potential food applications include especially vacuum or skin-packaged products, e.g. vacuum-packaged meat, fish, poultry or cheese. Several antimicrobial compounds have been combined with different types of carriers (plastic and rubber articles, paper-based materials, textile fibrils and food-packaging materials). Until now, however, few antimicrobial concepts have found applications as a food-packaging material. Antimicrobial packaging materials cannot legally be used in the EU at the moment. The potential use would require amendments of several different legal texts involving areas such as food additives, food packaging, hygiene, etc. The main objective of this paper is to provide a state of the art about the different types of antimicrobial concepts, their experimental development and commercialization, and to present a case study summarizing the results of investigations on the feasibility of a low-density polyethylene (LDPE)-film containing triclosan to inhibit microbial growth on food surfaces and consequently prolong shelf-life or improve microbial food safety. In contrast with the strong antimicrobial effect in in-vitro simulated vacuum-packaged conditions against the psychrotrophic food pathogen L. monocytogenes, the 1000 mg kg(-1) containing triclosan film did not effectively reduce spoilage bacteria and growth of L. monocytogenes on refrigerated vacuum-packaged chicken breasts stored at 7 degrees C.

Animals↗

PubMed2001

Effect of high oxygen modified atmosphere packaging on microbial growth and sensorial qualities of fresh-cut produce.

The application of High Oxygen Atmospheres (HOA) (i.e. > 70% O2) for packaging ready-to-eat vegetables was evaluated as an alternative technique for low O2 Equilibrium Modified Atmosphere (EMA) packaging (3% O2-5% CO2-balance N2) for respiring products. Comparative experiments between both techniques were performed in-vitro and in-vivo. Typical spoilage causing microorganisms (Pseudomonas fluorescens, Candida lambica), the moulds Botrytis cinerea, Aspergillus flavus and the opportunistic psychrotrophic human pathogenic microorganism associated with refrigerated minimally processed vegetables. Aeromonas caviae (HG4), showed a retarded growth during the conducted in-vitro studies at 4 degrees C in 70%, 80% and 95% O2 as examples of HOA compared to the in-vitro experiments in 5% O2 (as example of EMA packaging) and the effect was more pronounced in 95% O2. The effect of the high O2-concentrations on the human pathogen Listeria monocytogenes resulted in an extended lag phase (95% O2). The plant pathogen Erwinia carotovora was increasingly stimulated by increasing high O2-concentrations. During a storage experiment of three types of ready-to-eat vegetables (mushroom slices, grated celeriac and shredded chicory endive), which are sensitive to enzymatic browning and microbial spoilage, the effect of EMA and HOA (95% O2-5% N2) on their quality and shelf life was compared. High O2 atmospheres were found to be particularly effective in inhibiting enzymatic browning of the tested vegetables. Also, the microbial quality was better as a reduction in yeast growth was observed. The HOA can be applied as an alternative for low O2 modified atmospheres for some specific types of ready-to-eat vegetables, sensitive to enzymatic browning and spoilage by yeasts.

Bacteria↗

PubMed2001

Evaluation of culture media for enrichment and isolation of Shigella sonnei and S. flexneri.

The performance of Gram-negative (GN) broth with (10 microg/ml) and without novobiocin, Shigella broth (SB) with 0.5 and 3.0 microg/ml novobiocin, all incubated at 37 degrees C (SB with 3.0 microg/ml novobiocin also at 42 degrees C) and buffered brilliant green bile glucose (EE) broth with 1.0 microg/ml novobiocin incubated at 37 and 42 degrees C were evaluated for resuscitation and growth of Shigella sonnei and S. flexneri (eight strains; unstressed, chill-stressed and acid-stressed) and non-shigellae (11 strains). GN broth with or without novobiocin supported significantly less growth of Shigella sp. No significant differences in growth of shigellae were obtained between the other culture media. Performance depended more on the Shigella strain used. None of the tested media were significantly superior for suppressing the competitive flora. Electivity and selectivity of MacConkey agar (MAC), tergitol-7 agar (T7), desoxycholate citrate agar (DCA), xylose lysine desoxycholate agar (XLD), Salmonella Shigella agar and Hektoen enteric agar (HEA) were determined by ecometric testing. HEA confirmed to be a high selective medium for both non-shigellae and stressed Shigella sp. Klebsiella sp., Enterobacter sp., Citrobacter sp.. Salmonella sp. and the Escherichia strains can mask the presence of shigellae. In vitro competition experiments and experiments with artificially contaminated foods showed higher resistance of S. sonnei than S. flexneri towards the stress imposed by the food matrix and its indigenous flora. Reliable detection, however, of shigellae in foods with the current enrichment and isolation media was not achieved.

Agar↗

PubMed2001

Influence of acetate and CO2 on the TMAO-reduction reaction by Shewanella baltica.

In this work, the TMAO-reduction by Shewanella baltica, one of the representative spoilage organisms in modified atmosphere packaged marine fish fillets, and the effect of acetate and CO2 on this reduction were studied in vitro. The growth of S. baltica and the corresponding evolution of some compounds (acetate, lactate, pyruvate, glucose and trimethylamine (TMA)) were followed during storage at 4 degrees C in two types of broths. The first medium was a defined medium (pH = 6.8) to which lactate or pyruvate was added as hydrogen donor. Pyruvate showed to be more efficient as H-donor for S. baltica than lactate, as growth was much faster when equimolar amounts of pyruvate instead of lactate were present. Although the growth of S. baltica, when pyruvate is used as H-donor and no acetate is added, was not much inhibited by the CO2-atmosphere, CO2 had a pronounced effect on the studied reactions as it partly inhibited the reduction of pyruvate to acetate. The effect of acetate on this reaction was, on the other hand, not significant. To simulate the reactions occurring in situ, a buffered fish extract (pH = 6.8) was used. In spite of the neutral pH, the growth of S. baltica in this medium was highly inhibited by relatively small concentrations of acetate (< 0.3%). When 0.1% of acetate was added to the fish extract, less acetate was formed and lactate was more slowly consumed in comparison to the experiments without the addition of acetate. The consumption of lactate and the production of acetate were almost completely inhibited when the fish extract contained 0.25% of acetate. Apparently, the addition of acetate inhibited the use of lactate as H-donor. After extended storage times (17 days at 4 degrees C) TMA production started. Most probably, alternative H-donors were used by S. baltica, from which the pathway seems to be less energy efficient. This can be deduced from the exceptional growth inhibition of S. baltica by small amounts of acetate. However, when practical storage times for fish (e.g. 6 days at 4 degrees C after packaging) are considered, growth and TMAO-reduction by S. baltica was completely inhibited during this period by 0.25% of acetate.

Acetates↗

PubMed2001

Effect of stress induced by suboptimal growth factors on survival of Escherichia coli O157:H7.

This study investigated the growth and survival of E. coli O157:H7 exposed to a combination of suboptimal factors (22 degrees C, 7 degrees C, -18 degrees C/0.5% NaCl, 5.0% NaCl/pH 7.0, pH 5.4, pH 4.5/addition of lactic acid) in a simulation medium for red meat (beef gravy). Prolonged survival was noted as the imposed stress was more severe, and as multiple growth factors became suboptimal. At a defined temperature (7 degrees C or -18 degrees C), survival was prolonged at the more acid, more suboptimal pH (pH 4.5 > pH 5.4 > pH 7.0) while at a defined pH (pH 4.5), better survival was observed at 7 degrees C than at 22 degrees C. This suggests that application of the hurdle concept for preservation of food may inhibit outgrowth but induce prolonged survival of E. coli O157:H7 in minimal processed foods. At both 22 degrees C and 7 degrees C, the addition of lactic acid instead of HCl to reduce pH (to pH 4.5) resulted in a more rapid decrease of E. coli O157:H7. High survival was observed in beef gravy, pH 5.4 at -18 degrees C (simulation of frozen meat)-reduction of log 3.0 to log 1.9 after 43 days--and in beef gravy, pH 4.5 and 5% NaCl at 7 degrees C (simulation of a fermented dried meat product kept in refrigeration)--less than 1 log reduction in 43 days. In these circumstances, however, a high degree of sublethal damage of the bacterial cells was noted. The degree of sublethal damage can be estimated from the difference in recovery of the pathogen on the non-selective TSA medium and the selective SMAC medium.

Acids↗

PubMed2001

Effect of acid resistance of Escherichia coli O157:H7 on efficacy of buffered lactic acid to decontaminate chilled beef tissue and effect of modified atmosphere packaging on survival of Escherichia coli O157:H7 on red meat.

The present study examined the effect of pH-independent acid resistance of Escherichia coli O157:H7 on efficacy of buffered lactic acid to decontaminate chilled beef tissue. A varied level of acid resistance was observed among the 14 strains tested. Eight strains were categorized as acid resistant, four strains as acid sensitive, and two strains demonstrated acid-inducible acid resistance. The survival of an acid-resistant (II/45/4) and acid-sensitive (IX/8/16) E. coli O157:H7 strain on chilled beef tissue treated with 1 and 2% buffered lactic acid, sterile water, or no treatment (control) was followed. A gradual reduction of E. coli O157:H7 was noticed during the 10 days of storage at 4 degrees C for each of the treatments. Decontamination with 1 and 2% buffered lactic acid did not appreciably affect the pathogen. Differences in the pH-independent acid resistance of the strains had no effect on the efficacy of decontamination. The effect of modified atmosphere packaging (MAP) on survival of E. coli O157:H7 in red meat was also studied. MAP (40% CO2/60% N2) or vacuum did not significantly influence survival of E. coli O157:H7 on inoculated sliced beef (retail cuts) meat compared to packing in air. The relative small outgrowth of lactic acid bacteria during storage under vacuum for 28 days did not affect survival of E. coli O157:H7. Neither lactic acid decontamination nor vacuum or MAP packaging could enhance reduction of E. coli O157:H7 on beef, thus underlining the need for preventive measures to control the public health risk of E. coli O157:H7.

Adaptation, Physiological↗

PubMed2000

Shelf life of modified atmosphere packed cooked meat products: addition of Na-lactate as a fourth shelf life determinative factor in a model and product validation.

Cooked meat products are often post-contaminated because of a packaging and/or slicing step after the pasteurisation process. The shelf life is therefore limited and can be extended by adding Na-lactate. A previously developed model for the spoilage of gas packed cooked meat products, including temperature, water activity and dissolved CO2 as independent variables, was extended with a fourth factor: the Na-lactate concentration in the aqueous phase of the meat product. Models were developed for the maximum specific growth rate mu(max) and the lag phase lambda of the specific spoilage organism Lactobacillus sake subsp. carnosum. Quadratic response surface equations were compared with extended Ratkowsky models. In general, response surface equations fitted the experimental data best but in the case of mu(max) the response surface model predicted illogical growth behaviour at low water activities and high Na-lactate concentrations. A extensive product validation of the mathematical models was performed by means of inoculated as well as naturally contaminated industrially prepared cooked meat products. The deviations of the experimentally determined versus predicted growth parameters in inoculated cooked meat products were in general small. Both types of models were also able to predict the shelf life of naturally contaminated cooked meat products, except for pâté where an under-estimation of the shelf life was predicted by the response surface equations. The validation studies revealed higher accuracy of the extended Ratkowsky models in comparison to the response surface equations. A significant shelf life extending effect of Na-lactate was predicted, which was more pronounced at low refrigerated temperatures. A synergistic effect has also been noticed between Na-lactate and carbon dioxide which, at least partly, could be explained by the pH-decreasing effect of CO2.

Animals↗

PubMed2000

Modification of the bile salts-Irgasan-brilliant green agar for enumeration of Aeromonas species from food.

The present study evaluated the productivity of BIBG medium for the isolation of Aeromonas spp. from food and describes a modification of the BIBG medium (mBIBG) (increased pH (8.7), replacement of xylose by soluble starch as a carbon source, decreased concentration of bile salts) to increase its selectivity and electivity. Using the mBIBG medium, growth of the majority of the Enterobacteriaceae (9/10) was suppressed except for Citrobacter freundii. The mBIBG medium supported growth of Pseudomonas species but a clear distinction between Aeromonas and Pseudomonas colonies could be made. Interpretation of the mBIBG medium should be performed after 24 h of incubation. It was noted that three of the 27 Aeromonas strains tested did not develop on the mBIBG medium. The ability or inability to grow on a selective medium is strain-dependent. Enumeration of Aeromonas species (A. hydrophila LMG 3771, A. caviae LMG 3775, A. veronii biovar veronii LMG 9075, A. veronii biovar sobria LMG 13071) from artificially contaminated foods (shrimp, minced meat (beef/pork), precut leek, and shredded carrots) confirmed that the mBIBG medium is suitable for quantitative recovery of aeromonads (ca. 10(2)-10(7) cfu/g) in the presence of a high background flora (10(5)-10(6) cfu/g). Screening of naturally contaminated foods (vegetables, seafood, meat) for the presence of Aeromonas resulted in three out of 14 food samples showing presumptive Aeromonas colonies on mBIBG.

Aeromonas↗

PubMed2000

The use of immuno-magnetic separation (IMS) as a tool in a sample preparation method for direct detection of L. monocytogenes in cheese.

A sample preparation procedure was developed for direct detection of L. monocytogenes in cheese. The sample preparation protocol consisted of a 10-fold dilution and homogenization, a centrifugation step to precipitate large food particles, passage of the supernatant over a sieve and through a separatory funnel to further eliminate food particles and fat, a centrifugation step to recover the bacterial pellet and finally enzymatic digestion of the suspension to degrade the remaining small food particles. Recovery of L. monocytogenes was confirmed by plating on Oxford medium and confirmation of suspected colonies. This protocol enabled direct detection (without prior enrichment) of low numbers of L. monocytogenes (0.5-1.5 cfu/g cheese) from different types of cheese. The performance of Dynabeads Anti-Listeria (Dynal, Oslo, Norway) for selective recovery of L. monocytogenes and their applicability in the above mentioned procedure for direct detection of low numbers of L. monocytogenes from cheese was evaluated. IMS could not separate and recover L. monocytogenes from the food particles in the concentrated suspension. The use of IMS after a 24 h enrichment procedure (as recommended by the manufacturer) allowed for the detection of low numbers of L. monocytogenes (< 10 cfu/g). However, experiments in broth cultures showed that although the detection limit of IMS with Dynabeads Anti-Listeria was 40-100 cfu/ml, the ratio of L. monocytogenes to non-Listeria flora was not increased. Thus, selective enrichment or concentration of L. monocytogenes was not obtained.

Animals↗

PubMed2000

Isolation and identification of tetracycline resistant lactic acid bacteria from pre-packed sliced meat products.

In recent years, the food chain has been recognised as one of the main routes for transmission of antibiotic resistant bacteria between the animal and human population. In this regard, the current study aimed to investigate if tetracycline resistant (tetR) lactic acid bacteria (LAB) are present in ready-to-eat modified atmosphere packed (MAP) sliced meat products including fermented dry sausage, cooked chicken breast meat and cooked ham. From population graphs based on doubling tetracycline concentrations between 0 and 256 microg ml(-1), only fermented dry sausage was shown to contain a high-level retR LAB population (5.10(1) - 2,23.10(4) CFU/g), and this in four out of ten examined sausages. From these four positive sausages, a total of 100 strains were isolated on de Man, Rogosa and Sharpe-sorbic acid (MRS-S) agar without tetracycline (n = 45) and on MRS-S agar supplemented with a tetracycline breakpoint concentration of 64 microg ml(-1) (n = 55). Using resistance histograms derived from the disc diffusion method, all these strains were grouped as sensitive to rifampicin, erythromycin and ampicillin. All strains from the tetracycline-containing MRS-S plates were resistant to tetracycline. Identification with whole-cell protein profiling revealed that the total strain set represented four different species: Pediococcus pentosaceus, Lactobacillus plantarum, Lactobacillus sakei subsp. carnosus and Lactobacillus curvatus. All species are commonly associated with fermented dry sausage, either as starter culture or as natural contaminants. The latter three species were found to comprise all tetracycline resistant strains. To our knowledge, this is the first report providing evidence for the presence of tetR LAB in final ready-to-eat pre-packed fermented dry sausages.

Food Microbiology↗

PubMed2000

Incidence and identification of mesophilic Aeromonas spp. from retail foods.

Sixty-eight food samples were examined for the presence of mesophilic Aeromonas species both qualitatively and quantitatively. Aeromonads were isolated from 26% of the vegetable samples, 70% of the meat and poultry samples and 72% of the fish and shrimps. Numbers of motile aeromonads present in the food samples varied from <10(2) cfu g(-1) to >10(5) cfu g(-1). GLC analysis of FAMEs was used to identify a selection of presumptive Aeromonas colonies to fenospecies or genomic species level. Aeromonas strains belonging to the Aer. caviae complex, which also includes the potentially pathogenic genospecies HG4, were mostly isolated from vegetables but were also found in meat, poultry and fish. In addition, three strains of the virulent taxon Aer. veronii biovar sobria HG8 were isolated from poultry and minced meat. All members of the Aer. hydrophila complex, predominant in the fish, meat and poultry samples, were classified in the non-virulent taxon HG3. Although the significance of Aeromonas in foods remains undefined, the isolation of Aeromonas HG4 and HG8 strains from a variety of retail foods may indicate that these products can act as possible vehicles for the dissemination of food-borne Aeromonas gastroenteritis.

Aeromonas↗