Survival of a probiotic, Lactobacillus casei strain Shirota, in the gastrointestinal tract: Selective isolation from faeces and identification using monoclonal antibodies

Lactobacillus casei strain Shirota (LCS) is a probiotic bacterium used in t he production of fermented milk products and lactic acid bacteria preparati ons. To investigate the survival of LCS in the gastrointestinal tract, we h ave developed a selective medium and specific monoclonal antibodies to isol ate and identify this strain. Selective LLV agar medium was prepared by mod ifying LBS medium, a selective medium for lactobacilli, through the replace ment of glucose with lactitol as a carbon source and vancomycin as a select ive antibiotic. Culture in LLV agar medium followed by ELISA using monoclon al antibodies specific for LCS was able to detect the organism in faeces. U sing this method, we studied the faecal recovery of LCS in individuals who drank 125 ml of fermented milk which contained 10(10) live LCS for 3 days. The mean recovery was about 10(7) live bacteria per gram of faeces, indicat ing that LCS survived transit through the gastrointestinal tract after inge stion of the fermented milk. (C) 1999 Elsevier Science B.V. All rights rese rved.