Role of Lactobacilli in Gastrointestinal Ecosystem

S. A. DENEV
Trakia University Department of Biology, Section of Microbiology, Agricultural Faculty, BG-6000 Stara Zagora, Bulgaria

Abstract

DENEV, S. A., 2006. Role of Lactobacilli in gastrointestinal ecosystem. Bulg. J. Agric. Sci., 12: 63-114

Lactobacilli are normal and important inhabitants of the gastrointestinal tract of human and animals. They constitute an integral part of healthy gastrointestinal microecology and have received considerable scientific attention. The role that lactobacilli play in the ecology of the gastrointestinal tracts of humans and animals may be of major importance, but it is as yet poorly understood.
The present review summarizes the current state of knowledge regarding the role of lactobacilli in gastrointestinal ecosystem. Topics covered include: nutritional and therapeutic benefits of lactobacilli; deconjugation of bile acids; neutralization of toxins and other intestinal reactions; protection against intestinal pathogens by production of antibacterial substances such as organic acids, hydrogen peroxide, bacteriocins and etc.; stabilization of intestinal microflora, excluding colonization of enteropathogenic bacteria by adhesion to the intestinal wall and competition for nutrients; reduction of the cholesterol level in blood serum by cholesterol assimilation; decrease risk of colon cancer by detoxification of toxic, mutagenic and carcinogenic substances, and modulation of fecal procarcinogenic enzymes such as b-Glucuronidase, azoreductase and nitroreductase; tumor suppression by stimulation of non-specific and specific immune response.

Key words: Lactobacilli, gastrointestinal microflora, gastrointestinal ecosystem, antagonistic, antimutagenic, anticarcinigenic, immunological effects
Abbreviations: GIT - Gastrointestinal tract; GIE - Gastrointestinal ecosystem; GIM - Gastrointestinal microflora; CE - Competitive exclusion; IT - Intestinal tract; LAB - Lactic acid bacteria; BSH - Bile salt hydrolase