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Food-borne pathogen-related biofilms in food processing environments pose significant risks to human health. To ensure human and environmental safety, natural substances with anti-microbial properties and generally recognized as safe (GRAS) status are the future disinfectants of the food industry. The use of postbiotics in food products is gaining attention due to their many benefits. Postbiotics are soluble substances produced by probiotics or released after their lysis, such as bacteriocins, biosurfactants (BSs), and exopolysaccharides (EPS). Postbiotics have drawn attention because of their clear chemical structure, safety dose parameters, long shelf life, and the content of various signaling molecules, which may have anti-biofilm and antibacterial activities. The main mechanisms of postbiotics to combat biofilm contain suppression of twitching motility, disturbing quorum sensing (QS), and reduction of virulence factors. However, there are obstacles to using these compounds in the food matrix because some factors (temperature and pH) can limit the anti-biofilm impact of postbiotics. Therefore, by using encapsulation or application of these compounds in packaging films, the effect of interfering factors can be eliminated. This review summarizes the concept and safety of postbiotics, focusing on their antibiofilm effect, as well as discussing the encapsulation of postbiotics and their application in packaging films. [ABSTRACT FROM AUTHOR]

Virus survival on fomites may represent a vehicle for transmission to humans. This study was conducted to optimize and validate a recovery method for the porcine respiratory and reproductive syndrome virus (PRRSV), a potential SARS-CoV-2 surrogate, from stainless steel. Coupons (1.5 × 1.5 cm) inoculated with ca. 7 logs TCID50 of PRRSV were dried for 15 min at room temperature, followed by incubation at 4°C and 35% relative humidity. After 1 h and 24 h, the coupons were processed by four different methods: vortex in DMEM media, vortex in DMEM media with beads, vortex in elution buffer, and shake in elution buffer. The rinsates were processed for titration using the TCID50 method in the MARC-145 cell line. All four methods were equally effective to recover the virus from the soiled SS surfaces (> 79% recovery). The amount of infectious virus recovered after 24 h was similar (P  > 0.05) to that recovered after 1 h, indicating that the virus was stable at 4°C for up to 24 h. Using an elution buffer followed by shaking was the least labor-intensive and most economical method. Therefore, this method will be used for future experiments on PRRSV survival and transfer from food-contact surfaces. [ABSTRACT FROM AUTHOR]

Some of the challenges of yeast encapsulation protocols are low phytochemical internalization rates and limited intracellular compartments of yeasts. This study uses an ultrasound‐assisted batch encapsulation (UABE) protocol to optimize the encapsulation of curcumin and fisetin by recovering nonencapsulated biomaterial and further incorporating it into nonloaded yeasts in three encapsulation stages (1ES, 2ES and 3ES). The effect of selected acoustic energies (166·7 and 333·3 W l−1) on the encapsulation efficiency (EE), yield (EY) and antioxidant activity retention were evaluated, and then, compared with a control process (without ultrasound treatment). Compared to the control, enhanced EEs were achieved for both curcumin (10·9% control to 58·5% UABE) and fisetin (18·6% control to 76·6% UABE) after 3ES and the use of 333·3 W l−1. Similarly, the yeast maximum loading capacity was improved from 6·6 to 13·4 mg g−1 for curcumin and from 11·1 to 26·4 mg g−1 for fisetin after UABE protocol. The antioxidant activity of produced biocapsules was positively correlated with the bioactive‐loaded content of yeasts when ultrasound treatment was applied. Overall, results from this study provide valuable information regarding UABE processes, and moreover, bring new and creative perspectives for ultrasound technology in the food industry. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes has a significant impact on the food industry by forming biofilms on food‐processing equipment. Tandem analysis of whole‐genome sequencing data with biofilm data from 166 environmental and food‐related L. monocytogenes isolates has revealed serotypic and genetic factors that strongly correlate with adherence and biofilm formation, such as lineage, plasmid harbourage, a three‐codon deletion in inlA and the presence of the stress survival islet 1 (SSI‐1). Strains from serotype 1/2b, the majority of which contained SSI‐1, formed the strongest biofilms, while serotype 4b strains, the majority of which did not contain SSI‐1, formed the weakest biofilms. When serotype 1/2a was separated by its SSI‐1 genotype, SSI‐1‐positive 1/2a strains demonstrated significantly higher capacity for biofilm formation after 3 days of growth at 30°C (P < 0·0001). Together, these findings indicate that SSI‐1 may contribute to serotype‐associated differences in the biofilm‐forming capacity in L. monocytogenes. Significance and Impact of the Study: Parallel analysis of whole‐genome sequences and serotype‐specific data was performed to identify genetic markers that correlate with increased adherence and biofilm formation in L. monocytogenes. The analyses revealed the hitherto unrecognized role of SSI‐1 in biofilm formation, contributing to deeper understanding of genetic factors that influence behaviour of the species in the food processing environment.. Significance and Impact of the Study: Parallel analysis of whole‐genome sequences and serotype‐specific data was performed to identify genetic markers that correlate with increased adherence and biofilm formation in L. monocytogenes. The analyses revealed the hitherto unrecognized role of SSI‐1 in biofilm formation, contributing to deeper understanding of genetic factors that influence behaviour of the species in the food processing environment. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the regularity of autoinducer‐2 (AI‐2) secretion during growth and the effect of the addition of various carbohydrates on AI‐2 secretion in Bifidobacterium longum subsp. longum BBMN68 were investigated. The results indicated that the AI‐2 concentration reached its highest level (2536·60 nmol l−1) at the early stationary growth phase, and then decreased to 1263·72 nmol l−1 at the late stationary growth phase in Bifidobacterium cultures. When the density of the cultures which mannose, fructose, sucrose and lactose had been added to reached an OD600 nm of 1·0, the AI‐2 concentrations in the cultures were 1953·84, 1637·34, 1200·99 and 1077·60 nmol l−1, respectively. These concentrations were all significantly higher than that of the control culture (1031·33 nmol l−1). Similarly, the addition of fructooligosaccharide significantly increased the AI‐2 concentrations to 2094·29 nmol l−1. This study provides the advanced evidence that certain carbohydrates promote the secretion of AI‐2, and that this occurs at the single cell level and is therefore unaffected by cell density. Significance and Impact of the Study: This study provided the advanced data of the regularity of autoinducer‐2 (AI‐2) secretion during growth and the promotion on AI‐2 secretion of different added carbohydrates in Bifidobacterium, which may be a new potential strategy to improve the acid resistance of Bifidobacterium applied in the food industry. [ABSTRACT FROM AUTHOR]

The consumption of fermented foods by human kind goes a long way back in history and there are as many types of fermented food as civilizations. Food Science and Technology has progressed from designing nutritional foods towards food with health improvement characteristics such as functional foods. In this sense, the area of food with properties to improve gastrointestinal health such as probiotics, prebiotics and synbiotics has been the most important segment within functional foods. Most of these products are dairy-based so the development of nondairy gut improvement products has been of great interest for the food industry, resulting in the rise of cereal-based probiotic and synbiotic products. Finally, through Nanoscience and the application of Nanotechnology techniques in the food sector, it has been possible to design fermented beverages with synbiotic properties, and the incorporation of nanoparticles with unique and specific bioactivity, which has opened a new horizon in this segment of food created to improve human health and well-being. Significance and Impact of the Study There is currently a great interest in producing healthy food in particular that which has an impact in improving the gastrointestinal health such as probiotics, prebiotics and synbiotics. Most of these functional foods are dairy based and have been greatly accepted worldwide. Nevertheless, there has been a need for the development of nondairy probiotic, prebiotic and synbiotic products. This has encouraged food scientists to study the feasibility of applying other fermenting substrates such as cereals for the development of innovative nondairy fermented functional foods. Therefore, in this review we have addressed the significance of applying cereals and their fractions for the development of probiotic, prebiotic and synbiotic beverages. Furthermore, we have presented the importance of including nanoscience and nanotechnology techniques for the creation of fermented cereal beverages that contain specific bioactive nanoparticles. Thus, this work provides the guidelines to promote the development of novel nano-designed fermented cereal beverages that could significantly have an impact on the health of the consumers. [ABSTRACT FROM AUTHOR]

Microbiological source tracking (MST) for food industry is a rapid growing area of research and technology development. In this paper, a new library-independent approach for MST is presented. It is based on a high-throughput liquid microcultivation and FTIR spectroscopy. In this approach, FTIR spectra obtained from micro-organisms isolated along the production line and a product are compared to each other. We tested and evaluated the new source tracking approach by simulating a source tracking situation. In this simulation study, a selection of 20 spoilage mould strains from a total of six genera ( Alternaria, Aspergillus, Mucor, Paecilomyces, Peyronellaea and Phoma) was used. The simulation of the source tracking situation showed that 80-100% of the sources could be correctly identified with respect to genus/species level. When performing source tracking simulations, the FTIR identification diverged for Phoma glomerata strain in the reference collection. When reidentifying the strain by sequencing, it turned out that the strain was a Peyronellaea arachidicola. The obtained results demonstrated that the proposed approach is a versatile tool for identifying sources of microbial contamination. Thus, it has a high potential for routine control in the food industry due to low costs and analysis time. Significance and Impact of the Study The source tracking of fungal contamination in the food industry is an important aspect of food safety. Currently, all available methods are time consuming and require the use of a reference library that may limit the accuracy of the identification. In this study, we report for the first time, a library-independent FTIR spectroscopic approach for MST of fungal contamination along the food production line. It combines high-throughput microcultivation and FTIR spectroscopy and is specific on the genus and species level. Therefore, such an approach possesses great importance for food safety control in food industry. [ABSTRACT FROM AUTHOR]

Clostridium perfringens epsilon toxin, staphylococcal enterotoxin B and shiga toxin are implicated in a number of diseases and food-borne intoxications and are considered potential agents for bioterrorism and warfare. Artificially generated aerosol is the likely mode of delivery of these for nefarious uses, potentially capable of causing mass destruction to human and animal health by inhalation of toxic bioaerosol. Multiplex and unambiguous detection of these agents is of paramount importance for emergency response in a biothreat scenario and for food safety. Multiple-reaction monitoring ( MRM) assay for simultaneous monitoring of the three toxins is reported here using reverse-phase high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. Three different peptides with two fragment ions each were considered for quantification and confirmation. One of the three MRM transitions from each toxin, which exhibited the best sensitivity, was selected for multiplexing of the assay. Simulating a biothreat scenario wherein the bioaerosol is collected in 10 ml of buffer, the multiplex assay was tested with blind samples with one or more of the three toxins even in the presence of interfering Escherichia coli lysate proteins. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of soy lecithin on the bile resistance of Lactobacillus plantarum. Six strains were cultured in MRS broth supplemented with soy lecithin at different concentrations. The strains incubated in MRS broth with 1·0% soy lecithin showed no inhibitory effect on cell growth. After culturing in MRS broth with 0·2-1·0% soy lecithin, the survival rate of harvested cells increased significantly ( P < 0·05) in the 0·3% bile challenge compared with the no added soy lecithin group. The cells incubated with 0·6% soy lecithin were able to grow in an MRS broth with a higher bile salt content. The surface hydrophobicity and cell leakage in the bile challenge were assessed to reveal the physical changes caused by the addition of soy lecithin. The cell surface hydrophobicity was enhanced and the membrane integrity in the bile challenge increased after culturing with soy lecithin. A shift in the fatty acid composition was also observed, illustrating the cell membrane change in the soy lecithin culture. Significance and Impact of the Study In this study, we report for the first time the beneficial effect of adding soy lecithin to an MRS broth on subsequent bile tolerance of Lactobacillus plantarum. Soy lecithin had no inhibitory effect on strain viability but significantly enhanced bile resistance. Surface hydrophobicity and cell integrity increased in strains cultured with soy lecithin. The observed shift in the cell fatty acid composition indicated changes to the cell membrane. As soy lecithin is safe for use in the food industry, its protective effects can be harnessed for the development of bile-sensitive strains with health-benefit functions for use in probiotic products. [ABSTRACT FROM AUTHOR]

In this study, we developed and validated a loop-mediated isothermal amplification ( LAMP) assay for Salmonella detection targeting bcfD gene, a conserved fimbrial operon gene existing in Salmonella. The Salmonella LAMP assay we developed successfully amplified 44 Salmonella strains (14 standard strains and 30 clinical isolates), but none of 9 non- Salmonella standard strains ( Proteus mirabilis, Listeria monocytogenes, Escherichia coli, Pseudomonas aeruginosa, Shigella flexneri, Shigella sonnei, Klebsiella pneumoniae, Campylobacter jejuni and Vibrio parahemolyticus). The detection limit was 5 CFU of Salmonella pure culture or 200 CFU of artificially spiked faeces per reaction system (equivalent to 5000 CFU g−1 of faeces), and this method could directly detect Salmonella in chicken faeces free of pre-enrichment in a reaction time of 25 min. Our experiments show that the LAMP method we developed is a rapid, sensitive, specific and practical method for Salmonella detection. The Salmonella LAMP assay can potentially serve as new on-site diagnostics in the food and agricultural industries. Significance and Impact of the Study A loop-mediated isothermal amplification (LAMP) assay was established to detect Salmonella targeting bcfD gene, a conserved fimbrial operon gene. The detection limit was 5 CFU of Salmonella pure culture or 200 CFU of artificially spiked faeces per reaction system (equivalent to 5000 CFU g−1 of faeces), and this method could directly detect Salmonella in chicken faeces free of pre-enrichment in a reaction time of 25 min. The Salmonella LAMP assay is a rapid, sensitive, specific and practical method for Salmonella detection and can potentially serve as new on-site diagnostics in the food and agricultural industries. [ABSTRACT FROM AUTHOR]

A total of 256 isolates of Staphylococcus aureus were isolated from 98 samples (34 swabs and 64 food samples) obtained from small or medium meat- and cheese-processing plants in Slovakia. The strains were genotypically characterized by multiple locus variable number of tandem repeats analysis ( MLVA), involving multiplex polymerase chain reaction ( PCR) with subsequent separation of the amplified DNA fragments by an automated flow-through gel electrophoresis. With the panel of isolates, MLVA produced 31 profile types, which was a sufficient discrimination to facilitate the description of spatial and temporal aspects of contamination. Further data on MLVA discrimination were obtained by typing a subpanel of strains by multiple locus sequence typing ( MLST). MLVA coupled to automated electrophoresis proved to be an effective, comparatively fast and inexpensive method for tracing S. aureus contamination of food-processing factories. Significance and Impact of the Study Subspecies genotyping of microbial contaminants in food-processing factories may facilitate identification of spatial and temporal aspects of the contamination. This may help to properly manage the process hygiene. With S. aureus, multiple locus variable number of tandem repeats analysis ( MLVA) proved to be an effective method for the purpose, being sufficiently discriminative, yet comparatively fast and inexpensive. The application of automated flow-through gel electrophoresis to separation of DNA fragments produced by multiplex PCR helped to improve the accuracy and speed of the method. [ABSTRACT FROM AUTHOR]

Use of stevia-derived sweeteners was recently officially approved by the European Commission, and their application in the food industry has increased, especially in functional foods. However, there are scarce data about the influence of stevia on probiotic bacteria, which are important both as an inhabitant of the human gut and as a functional food additive. Taking into consideration the broad application of Lactobacillus reuteri in functional foods, the aim of the research was to evaluate the influence of stevia glycosides on its growth. Six Lact. reuteri strains were tested for their ability to grow in the presence of stevioside and rebaudioside A (0·2-2·6 g l−1). The effect of stevia glycosides on biomass concentration, cell count, pH and lactic and acetic acid synthesis was analysed. Both glycosides impaired the growth of analysed strains. However, the inhibitory effect was strain specific, and the concentration-dependent effect was not observed for all parameters. The most pronounced concentration-dependent effect was on lactic and acetic acid production. Taking into account the observed strain-specific inhibitory effect of stevia glycosides, it could be suggested to evaluate the influence of them on each strain employed before their simultaneous application in functional foods. Significance and Impact of the Study The study showed that the growth of Lactobacillus reuteri strains was inhibited in the presence of stevia sweeteners stevioside and rebaudioside A. Probiotics, for example Lact. reuteri strains, are often used as functional additives in health foods and are an important natural inhabitant of the human gastrointestinal tract. Stevia glycosides application in food is increasing; yet, there are no data about the influence of stevia glycosides on Lact. reuteri growth and very few data on growth of other lactobacilli, either in probiotic foods or in the gastrointestinal tract. This research shows that it is necessary to evaluate the influence of stevia glycosides on other groups of micro-organisms in further research. [ABSTRACT FROM AUTHOR]

Cholesterol oxidation products ( COPs) are a group of compounds formed during processing and storage of foods from animal origin. After ingestion, COPs are absorbed in the intestine and can be distributed to serum and various tissues, potentially promoting a variety of toxic effects. Therefore, inhibition of their intestinal absorption may contribute to reduce the health risks associated with dietary intake of COPs. Some studies have shown that drugs and dietary compounds may inhibit the intestinal absorption of dietary COPs. However, proven cholesterol- and/or food toxins-binding lactic acid bacteria have not been previously evaluated as potential COPs removal agents. The aim of this study was to assess the ability of Lactobacillus casei ATCC334 to remove COPs in aqueous solution. Results showed the ability of both growing and resting cells to remove COPs ( ca. 30-60%). All COPs-bacterium interactions were specific and partly reversible, being resting cells the most efficient for COPs removal in a ranking order of 7- KC > 7α-OH/7β-OH > triol > 5,6β-EP > 5,6α-EP > 25-OH. Binding to the cell wall and/or cell membrane incorporation appears to be the most likely mechanisms involved on COPs removal by L. casei ATCC 334. Significance and Impact of the Study The results of this work demonstrate for the first time the ability of a specific lactic acid bacterial strain to remove cholesterol oxidation products from an aqueous solution. This finding highlights the promising biological protective role of this bacterium as a potential removal agent of these toxic compounds. [ABSTRACT FROM AUTHOR]

In this study, the dissipation of pirimiphos-methyl during wheat fermentation by Lactobacillus plantarum was investigated. Sample preparation for GC/ MS detection of pirimiphos-methyl residues from fermented wheat substrate was carried out by two steps: extraction with 25 mL of methanol : acetone = 1 : 1 solvent mix for 30 min, followed by clean-up procedure through a glass column with florisil coupled with elution by 25 mL of ethyl acetate : acetone = 4 : 1. To obtain the highest pesticide degradation level, the fermentation conditions were optimized according to response surface methodology. Our results showed that L. plantarum was able to reduce the level of pirimiphos-methyl in wheat. Although pirimiphos-methyl was partially labile during sterilization prior inoculation (~37-50%), and there was also spontaneous chemical degradation of pesticide (~6-11%), overall L. plantarum enhanced degradation from 15 to 34%, that is, to nearly 81%. Additionally, the effect of pirimiphos-methyl on the lactobacilli growth, and efficiency of fermentation, was studied where pirimiphos-methyl inhibit the growth of bacteria in concentrations higher than 5 mg kg−1, while the presence of pirimiphos-methyl did not overall affect the lactic acid fermentation. Significance and Impact of the Study Pesticide residues are an unavoidable part of the environment due to their extensive applications in agriculture. As wheat is a major cultivated cereal, the presence of pesticide residues in wheat is a real concern to human health. Reduction in pesticide residues during fermentation has been studied, but there is a lack of data regarding pesticide residues dissipation during cereal fermentation. Present work investigates the dissipation of pirimiphos-methyl during wheat fermentation by L. plantarum. Results are confirmation that food-processing techniques can significantly reduce the pesticide residues in food, offering a suitable means to tackle the current scenario of unsafe food. [ABSTRACT FROM AUTHOR]

Contamination of food industrial environments and recontamination of finished products by Chrysonilia sitophila and Hyphopichia burtonii have long represented serious problems for the bakery industries. As one of the most common ways to slow down or avoid fungal spoilage on bakery products is the use of ethanol, in the present work the effect of this substance has been assessed on growth of two of the most frequently occurring associated moulds, C. sitophila and H. burtonii, by means of tests on both synthetic media and sliced bread. Test on synthetic media: H. burtonii was less markedly affected in lag-phase duration and radial growth rates by the addition of ethanol to DG18 and the reduction in incubation temperature than C. sitophila that failed to grow at the highest concentrations of ethanol tested (2·0 and 4·0% at 15°C; 4·0% at 25°C). Test on sliced bread: ethanol proved to be effective to prevent spoilage by C. sitophila even at the lowest concentration tested (0·8%, w/w), while higher concentrations (2·0%, w/w) were needed to prevent spoilage by H. burtonii. Significance and Impact of the Study This study shows that ethanol could represent an effective barrier to prevent spoilage of bakery products by associated moulds such as Chrysonilia sitophila and Hyphopichia burtonii, whose growth on packed and sliced bread was inhibited at very low (0·8%) or medium (2·0%) ethanol concentrations, respectively. The results obtained represent a fundamental point of reference for the bakery industries, as they can apply them in the productive practice to avoid spoilage by C. sitophila and H. burtonii on their products. [ABSTRACT FROM AUTHOR]

Propidium monoazide is a DNA-intercalating dye. PMA- qPCR has been reported as a novel method to detect live bacteria in complex samples. In this study, this method was used to monitor the sterilization effects of UHP, ultrasound and high PEF on Escherichia coli O157: H7. Our results showed that all three sterilization techniques are successful to kill viable E. coli O157: H7 cells under their appropriate conditions. PMA- qPCR can effectively monitor the amount of DNA released from viable E. coli O157: H7 cells, and the results from PMA- qPCR were highly consistent with those from plate counting after treatment with UHP, ultrasound and high PEF. The maximal Δ Ct between PMA- qPCR and qPCR obtained in this study was 10·39 for UHP, 5·76 for ultrasound and 2·30 for high PEF. The maximal sterilization rates monitored by PMA- qPCR were 99·92% for UHP, 99·99% for ultrasound and 100% for high PEF. Thus, PMA- qPCR can be used to detect the sterilization effect on food and water supplies after treatment with UHP, ultrasound and high PEF. [ABSTRACT FROM AUTHOR]

Salmonella spp. are an important cause of food-borne infections throughout world, and the availability of rapid and simple detection techniques is critical for the food industry. Salmonella enterica serovars Enteritidis and Typhimurium cause the majority of human gastroenteritis infections, and there are a reported 40 000 cases of salmonellosis in the United States each year. A novel rapid and simple isothermal target and probe amplification (iTPA) assay that rapidly amplifies target DNA ( Salmonella invA gene) using a FRET-based signal probe in an isothermal environment was developed for detection Salmonella spp. in pre-enriched food samples. The assay was able to specifically detect all of 10 Salmonella spp. strains without detecting 40 non- Salmonella strains. The detection limit was 4 × 10 CFU per assay. The iTPA assay detected at an initial inoculum level of <10 CFU in the pre-enriched food samples (egg yolk, chicken breast and peanut butter). This detection system requires only a water bath and a fluorometer and has great potential for use as a hand-held device or point-of-care-testing diagnostics. The iTPA assay is sensitive and specific and has potential for rapid screening of Salmonella spp. by food industry. [ABSTRACT FROM AUTHOR]

Aim: To enhance the information pertaining to the epidemiology of a collection of 378 Listeria spp . isolates obtained from several food-processing plants in Ireland over a 3- year period (2004-2007). Methods and results: The collection was characterized by pulsed-field gel electrophoresis (PFGE). The most prevalent pulse-type was PFGE profile I ( n = 14·5%) that consisted mainly of environmental Listeria spp. samples. Serotyping of 145 Listeria monocytogenes isolates was performed. The most common serovar was 1/2a and comprised 57·4% ( n = 77) of the L. monocytogenes collection. The other serovars were as follows: 4b (14·1%, n = 19), 1/2b (9·7%, n = 13), 4c (4·4%, n = 6) and 1/2c (6·7%, n = 9), respectively. Eleven isolates were identified as non- Listeria spp., the remaining ten L. monocytogenes isolates were nontypeable. The antimicrobial susceptibility testing revealed the antibiotic that isolates displayed the most resistance to was gentamicin (5%) followed by sulfamethoxazole-trimethoprim (2%), tetracycline and ciprofloxacin (1·5%). Conclusions: The subtyping has indicated the diversity of the Listeria spp. The presence of serotype 1/2a, 1/2b and 4b in both raw and cooked ready-to-eat food products is a public health concern, as these serotypes are frequently associated with foodborne outbreaks and sporadic cases of human listeriosis. In addition, the emergence of antimicrobial-resistant L. monocytogenes isolates could have serious therapeutic consequences. Significance and Impact of Study: The molecular subtyping and the further characterization of these isolates may be valuable particularly in the context of a suspected common source outbreak in the future. [ABSTRACT FROM AUTHOR]

Aims: Bacterial cellulose is an extracellular polysaccharide secreted by Acetobacter xylinum, which has become a novel material increasingly used in food and medical industries. However, its broad application is limited by its low yield and high cost. 1-Methylcyclopropene (1-MCP) is a potent inhibitor to either exogenous or endogenous ethylene during the biological senescence of plants, which has been broadly applied in commercial preservation of fruits and vegetables. The purpose of this study was to investigate the effects of 1-MCP on both the growth of Acet.  xylinum and its cellulose production to demonstrate the potential enhancement of bacterial cellulose yield. Methods and Results: Three groups of samples were fermented under agitated culture with 125 rev min−1 rotational speed. To the culture media, 0·14 mg of 1-MCP contained in 100 mg dextrose powder was added on assigned days or on the first culture day only. Results from the measurement of bacterial cell concentration and bacterial cellulose yield at the end of a 12-day culture demonstrated that cultures excluding 1-MCP displayed a higher cell concentration and a lower cellulose production, while cultures containing 1-MCP produced 15·6% more cellulose (1-MCP added on day 1) and 25·4% (1-MCP added on each assigned day) with less biomass. Conclusions: 1-MCP was able to affect the growth of Acet. xylinum cells and resulted in increasing bacterial cellulose yield up to 25·4% over controls, which did not contain 1-MCP. Significance and Impact of the Study: This was the first study to use the growth inhibitor of plants to investigate its effects on bacterial growth and production. It also demonstrated a significant enhancement of bacterial cellulose yield by the addition of 1-MCP during the common agitated culture of Acet. xylinum. [ABSTRACT FROM AUTHOR]

In recent years it has become widely recognized that bacteriophages have several potential applications in the food industry. They have been proposed as alternatives to antibiotics in animal health, as biopreservatives in food and as tools for detecting pathogenic bacteria throughout the food chain. Bacteriophages are viruses that only infect and lyse bacterial cells. Consequently, they display two unique features relevant in and suitable for food safety. Namely, their safe use as they are harmless to mammalian cells and their high host specificity that allows proper starter performance in fermented products and keeps the natural microbiota undisturbed. However, the recent approval of bacteriophages as food additives has opened the discussion about ‘edible viruses’. In this review, we examine the promising uses of phages for the control of foodborne pathogens and the drawbacks on which more research is needed to further exploit these biological entities. [ABSTRACT FROM AUTHOR]

Aims: To compare several methods for detection of methicillin resistance in Staphylococcus aureus isolates from food. Methods and Results: Two hundred S. aureus isolates from food of animal origin were screened for methicillin resistance by a PCR assay specific for the mecA gene, an oxacillin agar screen test and a cefoxitin disk diffusion test. Six out of 200 strains (3%) were found to be methicillin-resistant Staphylococcus aureus (MRSA) by PCR. The oxacillin agar screen test detected only one of the MRSA isolates (sensitivity of 16·7%) and mischaracterized three additional strains as MRSA (specificity of 98·45%). None of the MRSA strains was detected by the cefoxitin test (sensitivity of 0%), while 15 methicillin-susceptible S. aureus (MSSA) strains were misclassified as resistant (specificity of 92·3%). Fifteen MSSA strains displayed a β-lactamase hyperproducer-like phenotype. The six MRSA ( mecA-positive) strains resembled the characteristics of heteroresistant strains. Conclusions: As MRSA of animal origin may display atypical phenotypes, PCR appears to be more reliable for detection of methicillin resistance in animal strains. Significance and Impact of the Study: The study stresses the need for implementing the methods of screening S. aureus from food of animal origin for methicillin resistance. [ABSTRACT FROM AUTHOR]

Aims: This study was aimed to investigate the effectiveness of high-pressure homogenization (HPH) against Alicyclobacillus acidoterrestris. Methods and Results: The susceptibility of three different strains of A. acidoterrestris (DSMZ 2498, Γ4 and c8) to HPH (500–1700 bar) was studied. The experiments were performed in a laboratory medium (malt extract broth) on cells and spores. HPH caused a significant reduction of the initial cell number (1–2 log CFU ml−1 at the highest pressures) in Γ4 and DSMZ 2498 strains, whereas the effect on the spores was less significant. Conclusions: This study showed that the susceptibility of A. acidoterrestris to HPH was strain-dependent: DSMZ 2498 seemed the most susceptible strain, whereas c8 was the most resistant one. Significance and Impact of the Study: The results of our study will provide useful information on the sensitivity of an emerging spoilage micro-organism, such as A. acidoterrrestris, to HPH. [ABSTRACT FROM AUTHOR]

Aims: The work is intended to explore the suitability of underutilized coconut water (a byproduct of food industry) for the production of exopolysaccharides (EPS) by Agrobacterium sp. CFR 24. Methods and Results: Besides checking the suitability of coconut water for the production of water-soluble (WS) and water-insoluble (WIS) EPS, certain fermentation parameters, such as initial pH, incubation period and kinetics of EPS production were investigated. The coconut water medium was found to support the production of both types of EPS. The optimal initial pH and temperature was found to be 6·0 and 30°C, respectively. In shake flask (150 rev min−1) studies, high-cell density inoculum resulted in the production of 11·50 g l−1 of WIS-EPS and 4·01 g l−1 WS-EPS after 72 and 96 h of fermentation, respectively. Conclusions: Coconut water was found suitable for the production of microbial EPS by Agrobacterium sp. CFR 24 strain. Under optimum conditions, it produced a good amount of WIS-EPS, which is comparable with that of the sucrose medium (11 g l−1). Significance and Impact of the Study: This is the first report on the use of coconut water as a fermentation medium for the production of any microbial EPS. Besides producing value-added products, use of this food industry byproduct, which is often being drained out, can significantly reduce the problem of environmental pollution. [ABSTRACT FROM AUTHOR]

j.-h. ryu, h. kim, j.f. frank and l.r. beuchat. 2004.The aim of this study was to determine the role of curli in attachment and biofilm formation byEscherichia coliO157:H7 on stainless steel.Three curli-deficient strains (43895−, 43894− and E0018−) and three curli over-producing strains (43895+, 43894+ and E0018+) ofE. coliO157:H7 were studied. Stainless steel coupons (SSC) were immersed in cell suspensions of each strain for 24 h at 4°C. The number of cells attached to SSC was determined. To determine the ability of attached cells to form biofilm, SSC were immersed in 10% of tryptic soya broth up to 6 days at 22°C. Curli-deficient and curli-producing strains did not differ in their ability to attach to SSC, but only curli-producing strains formed biofilms.Curli production byE. coliO157:H7 does not affect attachment of cells on stainless steel but curli-producing strains are better able to form biofilms.Curli production byE. coliO157:H7 enhances its ability to form biofilm on stainless steel, thereby potentially resulting in increased difficulty in removing or killing cells by routine cleaning and sanitizing procedures used in food-processing plants. [ABSTRACT FROM AUTHOR]

n. fegan, g. higgs, p. vanderlinde and p. desmarchelier. 2003. To determine the numbers of Escherichia coli O157 present in the faeces of naturally infected cattle. A combination of the most probable number (MPN) technique and automated immunomagnetic separation (AIMS) was used to enumerate E. coli O157 in cattle faeces from both pasture-fed and grain-fed animals. A total of 22 E. coli O157 positive faecal samples were enumerated for E. coli O157 (10 from pasture-fed and 12 from grain-fed animals). The numbers of E. coli O157 in cattle faeces varied from undetectable (<3 MPN g−1 of faeces) to 2·4 × 104 MPN g−1. There was no significant difference ( P = 0·06) between the numbers of E. coli O157 in pasture-fed or grain-fed cattle faeces, although the geometric mean (antilog of the mean of log10 transformed MPN values) was higher in grain-fed (130 MPN g−1) than in pasture-fed (13 MPN g−1). Although the number of samples tested is small, the results indicate that E. coli O157 make up a small proportion of the total E. coli population present in cattle faeces. Information on the numbers of E. coli O157 present in cattle will assist in developing more robust quantitative risk assessments and formulating intervention strategies. [ABSTRACT FROM AUTHOR]