The production of fermented foods is based on the use of starter cultures, for instance lactic acid bacteria that initiate rapid acidification of the raw material. Recently, new starter cultures of lactic acid bacteria with an industrially important functionality are being developed. The latter can contribute to the microbial safety or offer one or more organoleptic, technological, nutritional, or health advantages. Examples are lactic acid bacteria that produce antimicrobial substances, sugar polymers, sweeteners, aromatic compounds, vitamins, or useful enzymes, or that have probiotic properties.

http://mummified.persiangig.com/new_folder/lact1.pdf

Lactic acid bacteria as functional starter cultures for the food fermentation industry

Aims
To assess the ability of human intestinally derived strains of Lactobacillus and Bifidobacterium to produce γ-aminobutyric acid (GABA).

Methods and Results
Strains of Lactobacillus and Bifidobacterium were grown in medium containing monosodium glutamate (MSG). Growth of the bacteria and conversion of MSG to GABA were measured. Of 91 intestinally derived bacteria assessed, one Lactobacillus strain and four strains of Bifidobacterium produced GABA. Lactobacillus brevis DPC6108 was the most efficient of the strains tested, converting up to 100% of MSG to GABA. The ability of the cultured intestinal strains to produce GABA was investigated using a simple pH-controlled anaerobic faeces-based fermentation, supplemented with 30 mg ml−1 MSG. The addition of Lact. brevis DPC6108 to a faeces-based fermentation significantly increased the GABA concentration (P < 0·001), supporting the notion that this biosynthesis could occur in vivo.

Conclusions
The production of GABA by bifidobacteria exhibited considerable interspecies variation. Lactobacillus brevis and Bifidobacterium dentium were the most efficient GABA producers among the range of strains tested. The addition of Lact. brevis DPC6108 to the culturable gut microbiota increased the GABA concentration in fermented faecal slurry at physiological pH.

Significance and Impact of the Study
Identification of optimal MSG conversion to GABA by particular cultured elements of the commensal intestinal microbiota and the demonstration that this can occur under simulated in vivo conditions offer new prospects for microbiota modulation to promote health.

γ-Aminobutyric acid production by culturable bacteria from the human intestine.

The complex polymicrobial composition of human gut microbiota plays a key role in health and disease. Lachnospiraceae belong to the core of gut microbiota, colonizing the intestinal lumen from birth and increasing, in terms of species richness and their relative abundances during the host’s life. Although, members of Lachnospiraceae are among the main producers of short-chain fatty acids, different taxa of Lachnospiraceae are also associated with different intra- and extraintestinal diseases. Their impact on the host physiology is often inconsistent across different studies. Here, we discuss changes in Lachnospiraceae abundances according to health and disease. With the aim of harnessing Lachnospiraceae to promote human health, we also analyze how nutrients from the host diet can influence their growth and how their metabolites can, in turn, influence host physiology.

https://www.mdpi.com/2076-2607/8/4/573/pdf

The Controversial Role of Human Gut Lachnospiraceae.

Bifidobacteria, naturally present in the dominant colonic microbiota, represent up to 25% of the cultivable faecal bacteria in adults and 80% in infants. As probiotic agents, bifidobacteria have been studied for their efficacy in the prevention and treatment of a broad spectrum of animal and/or human gastrointestinal disorders, such as colonic transit disorders, intestinal infections, and colonic adenomas and cancer. The aim of this review is to focus on the gastrointestinal effects of bifidobacteria as probiotic agents in animal models and man. The traditional use of bifidobacteria in fermented dairy products and the GRAS ('Generally Recognised As Safe') status of certain strains attest to their safety. Some strains, especially Bifidobacterium animalis strain DN-173 010 which has long been used in fermented dairy products, show high gastrointestinal survival capacity and exhibit probiotic properties in the colon. Bifidobacteria are able to prevent or alleviate infectious diarrhoea through their effects on the immune system and resistance to colonization by pathogens. There is some experimental evidence that certain bifidobacteria may actually protect the host from carcinogenic activity of intestinal flora. Bifidobacteria may exert protective intestinal actions through various mechanisms, and represent promising advances in the fields of prophylaxis and therapy.

/pdf/review-article-bifidobacteria-as-probiotic-agents-3oyd05vro3.pdf

N.R. Martinez

Papers

Synthesis and utilisation of folate by yoghurt starter cultures and probiotic bacteria.