Toxicological evaluation of Microbacterium foliorum SYG27B-MF.

Abstract Microbacterium foliorum is a naturally occurring bacteria in cruciferous vegetables and ripened cheese. The safety of M. foliorum SYG27B-MF has been assessed in both acute and subchronic studies and a battery of mutagenicity and clastogenicity tests. In a single dose acute study, the LD 50 of M. foliorum SYG27B-MF was greater than 3 g/kg bw or 5.1 × 1016 colony forming unit (CFU)/kg bw, the highest dose tested. In a 90-day subchronic toxicity study in 80 Sprague-Dawley rats, no animals died and there were no treatment-related abnormalities at doses of 0, 500, 1000, or 2000 mg/kg bw. In a 90-day repeated toxicity test, the no-observed-adverse-effect level (NOAEL) M. foliorum SYG27B-MF was 2000 mg/kg/day or 3.4 × 1016 CFU/kg bw/day, the highest level tested. A mutagenicity study using reverse bacterial mutation tests and a genotoxicity study employing cultured hamster ovarian fibroblasts (CHO-K1) cell showed that M. foliorum SYG27B-MF was not mutagenic or clastogenic in the presence or absence metabolic activation. In an in vivo mouse micronucleus assay, M. foliorum SYG27B-MF did not induce did not induce micronuclei formation in the bone marrow cells of mice, indicating that it is non-clastogenic. The results from these studies support the safety of M. foliorum SYG27B-MF for use as a production organism for human food ingredients. Highlights • The LD 50 of M. Foliorum was well above 3 g/kg bw or 5.1 × 1016 CFU/kg bw in rats. • The NOAEL of M. foliorum SYG27B-MF was higher than 2000 mg/kg bw/day or 3.4 × 1016 CFU/kg bw/day in SD rats. • M. foliorum SYG27B-MF was found to be non-mutagenic and non-clastogenic. • M. foliorum SYG27B-MF appears to be safe as a production organism in human food ingredients. [ABSTRACT FROM AUTHOR]