The term "functional foods" comprises some bacterial strains and products of plant and animal origin containing physiologically active compounds beneficial for human health and reducing the risk of chronic diseases. Among the best known functional compounds probiotics, prebiotics and natural antioxidants should be given as examples. These substances can be obtained by biotechnological methods and by extraction from plant or animal tissues.
Due to antimicrobial properties, nisin is one of the most commonly used and investigated bacteriocins for food preservation. Surprisingly, nisin has had limited use in animal feed as well as there are only few reports on its influence on microbial ecology of the gastrointestinal tract (GIT). The present study therefore aimed at investigating effects of dietary nisin on broiler chicken GIT microbial ecology and performance in comparison to salinomycin, the widely used ionophore coccidiostat. In total, 720 one-day-old male Ross 308 chicks were randomly distributed to six experimental groups. The positive control (PC) diet was supplemented with salinomycin (60 mg/kg). The nisin (NI) diets were supplemented with increasing levels (100, 300, 900 and 2700 IU nisin/g, respectively) of the bacteriocin. The negative control (NC) diet contained no additives. At slaughter (35 days of age), activity of specific bacterial enzymes (α- and β-glucosidases, α-galactosidases and β-glucuronidase) in crop, ileum and caeca were significantly higher (P<0.05) in the NC group, and nisin supplementation decreased the enzyme activities to levels observed for the PC group. A similar inhibitory influence on bacterial activity was reflected in the levels of short-chain fatty acids (SCFA) and putrefactive SCFA (PSCFA) in digesta from crop and ileum; no effect was observed in caeca. Counts of Bacteroides and Enterobacteriacae in ileum digesta were significantly (P<0.001) decreased by nisin and salinomycin, but no effects were observed on the counts of Clostridium perfringens, Lactobacillus/Enterococcus and total bacteria. Like salinomycin, nisin supplementation improved broiler growth performance in a dose-dependent manner; compared to the NC group, the body weight gain of the NI900 and NI2700 groups was improved by 4.7 and 8.7%, respectively. Our findings suggest that dietary nisin exerts a mode of action similar to salinomycin and could be considered as a dietary supplement for broiler chickens.
Providing safe products and compliance of legal requirements is still a great challenge for food manufacturers regarding microbiological safety, especially in the context of Listeria monocytogenes food contamination. L. monocytogenes is a human pathogen, which, due to the ability of survival and proliferation in preservation conditions such as high salinity, acidity and refrigeration temperatures, is a significant threat to the food industry. Novel methods of elimination of the bacterial pathogen in food products and food processing environments are required. Among emerging technologies, one of the very promising solutions is using bacteriophages as natural control agents. This review focus on the major aspects of phage-based inhibition of L. monocytogenes in aspects of food safety. We describe an overview of foods and technological factors influencing the efficacy of phage use in biocontrol of L. monocytogenes. The most noteworthy are food matrix properties, phage concentration and stability, the time of phage application and product storage temperature. The combined methods, phage immobilization (active packing), pathogen resistance to phages and legislation aspects of antilisterial bacteriophage use in the food industry are also discussed.
Aims: We have developed a PCR‐based assay using custom designed panel of primers which allows rapid detection of class IIa bacteriocin‐coding genes. To demonstrate the applicability of the developed assay, the method was applied on 40 metagenomic DNA preparations isolated from native microbiota of Polish artisanal cheeses produced in the Tatra Mountains. Methods and Results: The developed assay was designed on the basis of a large scale alignment of class IIa bacteriocin‐coding genes. A panel of seven primer pairs with confirmed ability to detect class IIa bacteriocin‐coding sequences was obtained. The following study has revealed a superb bacteriocinogenic potential of all forty analysed cheese samples. Conclusions: The majority of obtained sequences were lactic acid bacteria (LAB) related, although some sequences showed significant similarity to bacteriocin‐coding sequences present in non‐LAB bacteriocin producers. The results suggest that several potentially new bacteriocin‐coding sequences were found. Significance and Impact of the Study: The developed assay can be extremely helpful in establishing whether isolates from the environment of interest have a potential of synthesizing antilisterial class IIa bacteriocins. Application of the approach may represent a useful tool contributing to ecological studies looking for valuable probiotic, bacteriocinogenic microbiota developing in foods.
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