The Effect of Lactulose on the Survival of Lactobacillus rhamnosus in the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) and in vivo

The effect of lactulose on the survival of Lactobacillus rhamnosus VTT E-97800 and on the colon microbiota and its metabolic activity was studied using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) model. L. rhamnosus VTT E-97800 and lactulose together enhanced the production of butyric acid and decreased ammonium concentration in the model. The numbers of Bacteroides were observed to decrease 2.5-2.0 log 10 cfu/ml during the SHIME experiment. In the subsequent in vivo studies the colonisation of the human colon by L. rhamnosus VTT E-97800 could be confirmed using either RAPD or RiboPrinter™ for the strain identification. RAPD showed that 10-60% more L. rhamnosus VTT E-97800 was detected in lactulose subjects compared with controls after strain feeding was discontinued indicating that lactulose might enhance the survival of the strain in the colon.