Acute oral toxicity and bacterial translocation studies on potentially probiotic strains of lactic acid bacteria

Three potentially probiotic lactic acid bacteria (LAB) strains, Lactobacill us rhamnosus HN001 (DR20(TM)), Lb, acidophilus HN017 and Bifidobacterium la ctis HN019 (DR10(TM)), have recently been identified and characterized, The present study was designed to evaluate the acute oral toxicity of these st rains to mice, and also to investigate bacterial translocation and gut muco sal pathology in BALB/c mice fed HN019, HN001 or HN017 fur 8 consecutive da ys at a high dose of 10(11)cfu/mouse/day. Results showed that these probiot ic strains had no adverse effect on general health status, feed intake, bod y weight gain and intestinal mucosal morphology (villus height, crypt depth , epithelial cell height and mucosal thickness), No viable bacteria were re covered from blood and tissue samples (mesenteric lymph nodes, li,er and sp leen) of mice, and no treatment-associated illness or death was observed. A ccording to these results, the oral LD50 Of HN019, HN001 and HN017 is more than 50 g/kg/day for mice, and their acceptable daily intake (ADI) value is 35 g dry bacteria per day for a 70-kg person, This suggests that the probi otic strains HN019, HN001 and HN017 are non-pathogenic and likely to be saf e for human consumption. (C) 2000 Elsevier Science Ltd. All rights reserved .