Editorial: Microbial Food Safety along the Dairy Chain

peer-reviewedMilk is susceptible to contamination with pathogenic and spoilage organisms and, therefore, Microbial food safety along the dairy chain is an important topic, from public health and industry perspectives. The dairy chain is an integral part of global food supply, with dairy food products a staple component of recommended healthy diets. The dairy food chain from production through to the consumer is complex, with various opportunities for microbial contamination of ingredients or food products, and as such interventions are key to preventing or controlling such contamination. Dairy foods often include a microbial control step in their production such as pasteurization, but in some cases may not, as with raw milk products. Microbial contamination may lead to a deterioration in food quality due to spoilage organisms, or may become a health risk to consumers should the contaminant be a pathogenic microorganism. As such food safety and food production are intrinsically linked

Biogenic Amines in Italian Pecorino Cheese

The quality of distinctive artisanal cheeses is closely associated with the territory of production and its traditions. Pedoclimatic characteristics, genetic autochthonous variations, and anthropic components create an environment so specific that it would be extremely difficult to reproduce elsewhere. Pecorino cheese is included in this sector of the market and is widely diffused in Italy (∼62.000t of production in 2010). Pecorino is a common name given to indicate Italian cheeses made exclusively from pure ewes’ milk characterized by a high content of fat matter and it is mainly produced in the middle and south of Italy by traditional procedures from raw or pasteurized milk. The microbiota plays a major role in the development of the organoleptic characteristics of the cheese but it can also be responsible for the accumulation of undesirable substances, such as biogenic amines (BA). Bacterial amino acid decarboxylase activity and BA content have to be investigated within the complex microbial community of raw milk cheese for different cheese technologies. The results emphasize the necessity of controlling the indigenous bacterial population responsible for high production of BA and the use of competitive adjunct cultures could be suggested. Several factors can contribute to the qualitative and quantitative profiles of BA’s in Pecorino cheese such as environmental hygienic conditions, pH, salt concentration, water activity, fat content, pasteurization of milk, decarboxylase microorganisms, starter cultures, temperature and time of ripening, storage, part of the cheese (core, edge), and the presence of cofactor (pyridoxal phosphate, availability of aminases and deaminases). In fact physico-chemical parameters seem to favor biogenic amine-positive microbiota; both of these environmental factors can easily be modulated, in order to control growth of undesirable microorganisms. Generally, the total content of BA’s in Pecorino cheeses can range from about 100–2400 mg/kg, with a prevalence of toxicologically important BA’s, tyramine and histamine. The presence of BA is becoming increasingly important to consumers and cheese-maker alike, due to the potential threats of toxicity to humans and consequent trade implications

Lactiplantibacillus plantarum associated to fermented foods: in vitro evidences for its beneficial role in ameliorating intestinal inflammation

Fermented food microbes have recently recovered scientific interest for their health-promoting potential. Among them, Lactiplantibacillus (Lpb.) plantarum strains, with a long history as starter cultures in the production of a wide variety of fermented foods, showed the potential to affect host health in several in vitro and in vivo studies. Our study was aimed to investigate selected Lpb. plantarum strains, isolated from fermented foods, to face oxidative stress and related inflammatory damage at intestinal level, in order to be considered a promising strategy in intestinal inflammatory diseases. For this purpose, we examined food- and human- associated Lpb. plantarum strains for their in vitro capacity to tolerate oxidative stress as well as for their antioxidant potential by three different chemical assays (DPPH, ABTS and FRAP). In addition, the specific ability of each strain to modulate reactive oxygen species (ROS) levels in response to either oxidative or inflammatory stress and to reduce IL-17A, IL-17F and IL-23 release in an inflamed intestinal cell model was investigated. Overall, the results show that Lpb. plantarum endure high levels of induced oxidative stress through partially neutralizing ROS, whereas they elicit their production when co‑cultured with normal mucosa intestinal cells (NCM460). Moreover, pre‑treatment with food‑borne Lpb. plantarum significantly reduces pro ‑inflammatory cytokines IL‑17F and IL‑23 levels in inflamed NCM460 cells. Both IL-23 and IL-17 are pro-inflammatory cytokines with an active role in the pathophysiology of chronic inflammatory disorders, thus targeting the IL23/IL17 axis could be a considerable way to treat intestinal inflammatory diseases. Our results suggest that food‑vehicled Lpb. plantarum strains might reduce inflammatory response in intestinal cells by directly modulating local ROS production and by triggering the IL‑23/IL‑17 axis with future perspectives on health benefits derived by the consumption of functional foods enriched with selected strains

Lactic Acid Bacteria Exopolysaccharides Producers: A Sustainable Tool for Functional Foods

Lactic acid bacteria (LAB) used in the food industry, mainly for the production of dairy products, are able to synthetize exopolysaccharides (EPS). EPS play a central role in the assessment of rheological and sensory characteristics of dairy products since they positively influence texture and organoleptic properties. Besides these, EPS have gained relevant interest for pharmacological and nutraceutical applications due to their biocompatibility, non-toxicity and biodegradability. These bioactive compounds may act as antioxidant, cholesterol-lowering, antimicrobial and prebiotic agents. This review provides an overview of exopolysaccharide-producing LAB, with an insight on the factors affecting EPS production, their dairy industrial applications and health benefits

Bacterial composition, genotoxicity, and cytotoxicity of fecal samples from individuals consuming omnivorous or vegetarian diets

This study analyzes the composition of viable fecal bacteria and gut toxicology biomarkers of 29 healthy volunteers, who followed omnivorous, lacto-ovo-vegetarian, or vegan diets. In particular, the research was focused on the prevalence of some representative viable bacteria from the four dominant phyla (Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria) commonly present in human feces, in order to evaluate the relationship between microorganisms selected by the habitual dietary patterns and the potential risk due to fecal water (FW) genotoxicity and cytotoxicity, considered as biomarkers for cancer risk and protective food activity. The relative differences of viable bacteria among dietary groups were generally not statistically significant. However, compared to omnivores, lacto-ovo-vegetarians showed low levels of total anaerobes. Otherwise, vegans showed total anaerobes counts similar to those of omnivores, but with lower number of bifidobacteria and the highest levels of bacteria from the Bacteroides-Prevotella genera. FW genotoxicity of lacto-ovo-vegetarians resulted significantly lower either in relation to that of omnivores and vegans. Lacto-ovo-vegetarians also showed the lowest levels of cytotoxicity, while the highest were found for vegans. These results highlighted that lacto-ovo-vegetarian diet was particularly effective in a favorable modulation of microbial activity, thus contributing to a significant reduction of the genotoxic and cytotoxic risk in the gut

Comparative Genomics of Lactiplantibacillus plantarum: Insights Into Probiotic Markers in Strains Isolated From the Human Gastrointestinal Tract and Fermented Foods

Lactiplantibacillus (Lpb.) plantarum is a versatile species commonly found in a wide variety of ecological niches including dairy products and vegetables, while it may also occur as a natural inhabitant of the human gastrointestinal tract. Although Lpb. plantarum strains have been suggested to exert beneficial properties on their host, the precise mechanisms underlying these microbe-host interactions are still obscure. In this context, the genome-scale in silico analysis of putative probiotic bacteria represents a bottom-up approach to identify probiotic biomarkers, predict desirable functional properties, and identify potentially detrimental antibiotic resistance genes. In this study, we characterized the bacterial genomes of three Lpb. plantarum strains isolated from three distinct environments [strain IMC513 (from the human GIT), C904 (from table olives), and LT52 (from raw-milk cheese)]. A whole-genome sequencing was performed combining Illumina short reads with Oxford Nanopore long reads. The phylogenomic analyses suggested the highest relatedness between IMC513 and C904 strains which were both clade 4 strains, with LT52 positioned within clade 5 within the Lpb. plantarum species. The comparative genome analysis performed across several Lpb. plantarum representatives highlighted the genes involved in the key metabolic pathways as well as those encoding potential probiotic features in these new isolates. In particular, our strains varied significantly in genes encoding exopolysaccharide biosynthesis and in contrast to strains IMC513 and C904, the LT52 strain does not encode a Mannose-binding adhesion protein. The LT52 strain is also deficient in genes encoding complete pentose phosphate and the Embden-Meyerhof pathways. Finally, analyses using the CARD and ResFinder databases revealed that none of the strains encode known antibiotic resistance loci. Ultimately, the results provide better insights into the probiotic potential and safety of these three strains and indicate avenues for further mechanistic studies using these isolates

Influence of organic viticulture on non- Saccharomyces wine yeast populations

This study evaluated the population dynamics of non-Saccharomyces biota during spontaneous fermentation of organic musts. Non-Saccharomyces yeasts were found to be present at high levels during all fermentations. A total of 543 yeast colonies were isolated, 190 from Lysine-Medium (LM) agar, 254 from Wallerstein Laboratory Nutrient (WLN) agar and 99 from YPD agar. To estimate yeast population dynamics during spontaneous fermentation a genotypic approach was applied. PCR-RFLP of the ITS1-5.8S rDNA-ITS2 region and sequence determination of the D1/D2 region of the 26S rRNA gene enabled identification of the yeast isolates at the species level. Hanseniaspora uvarum, Metschnikowia fructicola and Candida zemplinina predominated, while Issatchenkia terricola, Issatchenkia orientalis and Pichia sp. were identified with a lower frequency. Hanseniaspora uvarum, M. fructicola and C. zemplinina represented 43%, 31% and 11% of the total non-Saccharomyces population isolated, respectively. Some yeast isolates were shown to be closely related to Hanseniaspora spp. and Candida spp. on the basis of the D1/D2 sequences. Based on those results, the coexistence of different Hanseniaspora and Pichia species in grape musts was supposed, and their complete identification was achieved using additional molecular markers. Moreover, strain typing and differentiation was carried out by RAPD-PCR. High strain polymorphisms were observed in the different species. For some strains, appreciable properties were demonstrated both in vitro by the API-ZYM test and in must. In must microvinification some strains showed good fermentation performances, low production of acetic acid and a partial capability to degrade malic acid