Lack of genotoxicity and subchronic toxicity in safety assessment studies of a Clostridium beijerinckii formulation.

A powder formulation of viable Clostridium beijerinckii bacteria (CBEI) was evaluated in a battery of genotoxicity studies and 14-day and 90-day repeat-dose toxicity studies in rats to evaluate CBEI as a food ingredient. All studies followed Organisation for Economic Co-operation and Development (OECD) protocols. CBEI (nonviable) was not mutagenic in an in vitro bacterial reverse mutation assay and was not clastogenic in an in vitro mammalian chromosomal aberration test. Viable CBEI was not genotoxic when evaluated in an in vivo mammalian cell micronucleus assay administered at up to 2.30 × 1011 AFU/kg body weight/day. CBEI was administered to rats via gavage at target doses of 217, 434, and 868 mg/kg body weight/day (equivalent to 4.1 × 1010, 8.2 × 1010, and 1.64 × 1011 AFU/kg body weight/day) in a 14-day dose range-finding study and a 90-day repeat-dose study. Target doses were largely achieved based on analyses from 2 independent laboratories. No mortality or treatment-related adverse effects attributed to CBEI consumption were observed in any endpoint. Bacterial translocation from the intestinal tract to the liver, mesenteric lymph nodes and blood was observed, but only one bacterial colony was found to be CBEI. The no-observed-adverse-effect level (NOAEL) was concluded to be the highest dose tested: 868 mg/kg body weight/day (approximately 1.42 × 1011 AFU/kg body weight/day). These results confirm that CBEI was not genotoxic and was not toxic under the conditions of the conducted studies.