Effect of probiotics on five biochemical microflora-associated characteristics, in vitro and in vivo

Abstract

Background: Several bacterial strains, mainly those belonging to the genera Lactobacillus, Enterococcus, Streptococcus and Bi. dobacterium, are currently used as probiotics. Objective: The aim of this study was to investigate the influence of probiotics on .five biochemical microbial-related functions in vitro and in vivo, in gnotobiotic mice, by applying the GAC:MAC (germ-free animal characteristic/microflora-associated characteristic) concept. Design: Sixteen probiotics were monoinoculated in vitro and/or monoassociated to germ-free mice to investigate the following biochemical parameters in large intestinal samples: inactivation of tryptic activity, degradation of b-aspartylglycine and of mucin, conversion of bilirubin to urobilinogen and b-glucuronidase activity. Results: Lactobacillus reuteri 2010, L. rhamnosus strain 271, L. rhamnosus ATCC7469 and L. rhamnosus GG ATCC53103 expressed b-glucuronidase activity. The other parameters tested were not influenced by any of the probiotics. Conclusions: Bacterial b-glucuronidases have an important intestinal function. As many microbial–host and microbe–diet interactions occur in the gastrointestinal tract of mammals, microbial-related functions should be studied in greater detail in probiotics. Keywords: Germ-free, germ-free animal characteristic, b-glucuronidases, gnotobiotic mice, microflora-associated characteristic, probiotics.