Growth and adhesion to HT-29 cells inhibition of Gram-negatives by Bifidobacterium longum BB536 e Lactobacillus rhamnosus HN001 alone and in combination.

OBJECTIVE: The aim of this study was to test the inhibitory effect of supernatants of broth cultures of Bifidobacterium longum BB536 and Lactobacillus rhamnosus HN001, both individually and in combination, against Gram-negative strains (uropathogens, enteropathogens and a reference strain). Moreover, in vitro protection of B. longum BB536 and L. rhamnosus HN001, both individually and in combination, against pathogen adhesion to HT-29 cell line, was investigated. MATERIALS AND METHODS: The inhibitory activity was performed by the agar diffusion test and in vitro antagonistic activity against pathogen adhesion to human epithelial intestinal HT-29 cells was performed using standardized culture techniques. RESULTS: The study showed that B. longum BB536 and L. rhamnosus HN001, individually and in combination have inhibitory activity against the majority of the Gram negative strains tested. Furthermore, the results showed that both probiotic strains have a good capacity to inhibit pathogenic adhesion to HT-29 cells. Moreover, the ability of B. longum BB536 and L. rhamnosus HN001 to inhibit pathogenic adhesion increased when they were used in combination. DISCUSSION: The combination of B. longum BB536 and L. rhamnosus HN001 showed inhibitory activity against Gram-negatives and an improved ability to reduce their adhesion properties and to compete with them. CONCLUSIONS: The simultaneous presence of the two-probiotic strains could promote competitive mechanisms able to reduce the adhesion properties of pathogen strains and have an important ecological role within the highly competitive environment of the human gut.

Impact of gut microbiota on diabetes mellitus.

Various functions of the gut are regulated by sophisticated interactions among its functional elements, including the gut microbiota. These microorganisms play a crucial role in gastrointestinal mucosa permeability. They control the fermentation and absorption of dietary polysaccharides to produce short-chain fatty acids, which may explain their importance in the regulation of fat accumulation and the subsequent development of obesity-related diseases, suggesting that they are a crucial mediator of obesity and its consequences. In addition, gut bacteria play a crucial role in the host immune system, modulation of inflammatory processes, extraction of energy from the host diet and alterations of human gene expression. Dietary modulation of the human colonic microbiota has been shown to confer a number of health benefits to the host. Simple therapeutic strategies targeted at attenuating the progression of chronic low-grade inflammation and insulin resistance are urgently required to prevent or slow the development of diabetes in susceptible individuals. The main objective of this review is to address the pathogenic association between gut microbiota and diabetes, and to explore any novel related therapeutic targets. New insights into the role of the gut microbiota in diabetes could lead to the development of integrated strategies using probiotics to prevent and treat these metabolic disorders.

Microbiological characteristics of the probiotic strains B. longum BB536 and L. rhamnosus HN001 used in combination.

AIM: The aim of this study was to investigate the antagonistic activity between the probiotic strains Bifidobacterium longum (B. longum) BB536 and Lactobacillus rhamnosus (L. rhamnosus) HN001 (ZirCombi, Alfa Wassermann S.p.A., Italy) and to evaluate for the strains tested alone and in combination the resistance in simulated gastrointestinal conditions, the ability to adhere to epithelial intestinal cells and their competition for adhesion. METHODS: The antagonism between B. longum BB536 and L. rhamnosus HN001 was tested modifying the agar diffusion method. The in vitro resistance to gastrointestinal condition of the two strains used alone or in combination was tested using low pH (3.0, 2.5 and 2.0) and different concentrations of bile salts (0.3%, 0.5% and 0.7%). The adhesion ability and the competition for adhesivity on human colon cancer HT-29 cells were tested modifying quantitative methods described in literature. RESULTS: The results demonstrated that B. longum BB536 and L. rhamnosus HN001 showed no in vitro inhibition effect each other and a good resistance to low pH and to different concentrations of bile salts, that was enhanced when they were tested in combination. Moreover, the two strains tested alone and in combination showed a good adhesion on HT-29 cells and no mechanism of competition. CONCLUSION: The study suggests that B. longum BB536 and L. rhamnosus HN001 used in combination show no antagonism and could have functional endosymbiotic effects on intestinal host-microbiota.