Probiotics: What are they?
How to select new strains??
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Did you know that the term probiotic has been used for a long time? In Greek it means "for life". According to the definition, probiotics are live microorganisms that confer health benefits to the host when administered in adequate amounts.
Among functional foods, probiotics play a fundamental role in nutrition and health due to the various benefits conferring to the host's gastrointestinal tract microbiota. Probiotics can be consumed in dairy products, processed meats, vegetable products, fruit juices, cereal products, nutritional supplements, tablets, capsules, powder, and in medicines.
Most commercial probiotics are of bacterial origin, derived from the genera Lactobacillus and Bifidobacterium. Among the yeasts with probiotic potential, Saccharomyces boulardii (isolated from the lychee fruit) is the only commercialized strain. All probiotic strains are different, that is, strains of the same species will generally have different properties. Many studies have isolated new strains with probiotic potential by using some tests. The test used for their selection are the following: body temperature survival, stability against stomach acid and bile salts, ability to adhere to the intestinal mucosa, ability to colonize the human gastrointestinal tract, ability to produce antimicrobial compounds, and in vivo tests. Other recommended tests include susceptibility to antibiotics and evaluation of transferable antibiotic resistance genes.
The health benefits attributed to probiotics consumption include anti-cancer, anti-cholesterol, anti-depression and anti-anxiety, anti-obesity, and anti-diabetes activities.
The new techniques in metabolomics, proteomics, genomics and transcriptomics are used to evaluate the expression of genes and metabolites under different conditions related to the host.
Many studies carried out in foods and different environments may contain promising probiotics strains. For example Petrovic et al. (2020) isolated potential probiotic Enterococcus faecium strains from spontaneously fermented sausages. Moreover, potential yeasts from Saccharomyces cerevisiae and Pichia kluyveri have been isolated by Yildiran et al. (2019).
ŽUGIĆ PETROVIĆ, TANJA D. ET AL. Assessment of safety aspect and probiotic potential of autochthonous Enterococcus faecium strains isolated from spontaneous fermented sausage. Biotechnology Letters, p. 1-13, 2020.
YILDIRAN, HATICE; BAŞYİĞİT KILIÇ, GÜLDEN; KARAHAN ÇAKMAKÇI, AYNUR GÜL. Characterization and comparison of yeasts from different sources for some probiotic properties and exopolysaccharide production. Food Science and Technology, v. 39, p. 646-653, 2019.
Aline Galvão Tavares Menezes