Probiotics and prebiotics in animal feeding for safe food production

Here, we review what is known about the microorganisms present in raw milk, including milk from cows, sheep, goats and humans. Milk, due to its high nutritional content, can support a rich microbiota. These microorganisms enter milk from a variety of sources and, once in milk, can play a number of roles, such as facilitating dairy fermentations (e.g. Lactococcus, Lactobacillus, Streptococcus, Propionibacterium and fungal populations), causing spoilage (e.g. Pseudomonas, Clostridium, Bacillus and other spore-forming or thermoduric microorganisms), promoting health (e.g. lactobacilli and bifidobacteria) or causing disease (e.g. Listeria, Salmonella, Escherichia coli, Campylobacter and mycotoxin-producing fungi). There is also concern that the presence of antibiotic residues in milk leads to the development of resistance, particularly among pathogenic bacteria. Here, we comprehensively review these topics, while comparing the approaches, both culture-dependent and culture-independent, which can be taken to investigate the microbial composition of milk.

The complex microbiota of raw milk

ummary
Background
Probiotics are defined as live micro-organisms which confer a health benefit on the host. Although most probiotics are bacteria, one strain of yeast, Saccharomyces boulardii, has been found to be an effective probiotic in double-blind clinical studies.

Aims
To compare the main properties that differentiates yeast from bacteria and to review the properties of S. boulardii explaining its potential benefits as a probiotic.

Methods
The PubMed and Medline databases were searched using the keywords ‘probiotics’, ‘yeast’, ‘antibiotic associated diarrhea’, ‘Saccharomyces boulardii’,‘bacterial diarrhea’ and ‘inflammatory bowel disease’ in various combinations.

Results
Several clinical studies have been conducted with S. boulardii in the treatment and prevention of various forms of diarrhoea. Promising research perspectives have been opened in terms of maintenance treatment of inflammatory bowel diseases. The mechanism of S. boulardii’s action has been partially elucidated.

Conclusion
Saccharomyces boulardii is a strain of yeast which has been extensively studied for its probiotic effects. The clinical activity of S. boulardii is especially relevant to antibiotic-associated diarrhoea and recurrent Clostridium difficile intestinal infections. Experimental studies clearly demonstrate that S. boulardii has specific probiotic properties, and recent data has opened the door for new therapeutic uses of this yeast as an ‘immunobiotic’.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2036.2007.03442.x

Review article: yeast as probiotics-saccharomyces boulardii

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.

https://biblio.ugent.be/publication/4174905/file/4174948.pdf

Antimicrobial resistance in the food chain: a review.

Antibiotic resistance in non-enterococcal lactic acid bacteria and bifidobacteria

http://ssu.ac.ir/cms/fileadmin/user_upload/Mtahghighat/tfood/ARTICLES/koliat/Antibiotic_resistance_in_food_lactic_acid_bacteria—a_review.pdf

Shalini Mathur

Papers

Antibiotic resistance in food lactic acid bacteria--a review.

Starter cultures in dairy industry: A review