Adaptation of Bacteria to the Intestinal Niche: Probiotics and Gut Disorder

Abstract

The gastrointestinal tract is a complex ecosystem host to a diverse and highly evolved microbial community composed of hundreds of different microbial species. The interactions that occur between this complex microbial community and the human host have become the focus of scientific research due to increases in the incidence of illnesses associated with deficient or compromised microflora (e.g., gastrointestinal tract infections, inflammatory bowel disease (Crohn's disease and ulcerative colitis), irritable bowel syndrome, antibiotic-induced diarrhea, constipation, food allergies, cardiovascular disease, and certain cancers). Effective multidisciplinary research programs now complement conventional microbiology with molecular ecology techniques to provide culture-independent analysis of the gastrointestinal ecosystem. Furthermore, as we acquire an understanding of gut microflora composition and processes such as intestinal adherence, colonization, translocation, and immunomodulation, we are also elucidating mechanisms by which these can be influenced. This knowledge not only allows scientists to define the activities and interactions of "functional food"-borne beneficial bacteria in the gut, but will also provide the scientific basis for the development of innovative biotechnology-based products tailored to prevent specific diseases and promote overall human gastrointestinal health.

A Randomised Controlled Trial of a Probiotic Lactobacillus Strain in Healthy Adults: Assessment of its Delivery, Transit and Influence on Microbial Flora and Enteric Immunity

“…Gastrointestinal disorders where probiotics might be anticipated to have a therapeutic application include antibiotic-associated diarrhoea; bacterial overgrowth and other diarrhoeal syndromes; in ammatory bowel disease, and colonic cancer (1,12,36). Probiotics also offer the very real potential to deliver therapeutically relevant proteins including enzymes, vaccines and cytokines (37).…”

“…The intestinal micro ora is characterised by its density, diversity and complexity of interactions and is both an asset and a potential liability in health and disease, depending on genetic and other host susceptibility factors (1). There are up to 10-fold more bacteria in the human gut than cells in the body and this accounts for about 1 -2 kg of intestinal contents composed of an estimated 50 genera, belonging to over 400 separate species (2).…”

Human Intestinal Epithelial Cells Are Broadly Unresponsive to Toll-Like Receptor 2-Dependent Bacterial Ligands: Implications for Host-Microbial Interactions in the Gut

“…A wide variety of bacterial species reside within the human colon (61)(62)(63). Gram-positive aerobes such as Lactobacillus and Streptococcus spp.…”

Phage display reveals 52 novel extracellular and transmembrane proteins from Lactobacillus reuteri DSM 20016T

“…The effects of probiotics have been demonstrated in several studies (reviewed by Andersson et al, 2001;Ouwehand et al, 2002;Reid, 1999), but the mechanisms of action behind the effects are often not known. Properties considered important for probiotic activity of bacteria are: adherence to the intestinal surfaces and colonization of the host; reduction of colonization of pathogenic bacteria; production of antimicrobial substances; and interaction with the host and its immune system (reviewed by Dunne, 2001;Ouwehand et al, 1999;Reid & Burton, 2002). Extracellular proteins, i.e.…”