In vivo mammalian micronucleus test in mice confirms lack of genotoxic potential of a protein-rich powder derived from Xanthobacter sp. SoF1

The growing interest and demand for alternative protein sources has propelled research and production of protein-rich microbial biomass products for human consumption. The potential genotoxicity of a protein-rich biomass derived from Xanthobacter sp. SoF1 (SoF1), an autotrophic hydrogen-oxidizing bacteria, was evaluated in the bone marrow of male NMRI mice in the current work. This study was conducted as the final step of a comprehensive toxicological safety assessment that has been previously published. While a genotoxic evaluation including a bacterial reverse mutation test, an in vitro chromosomal aberration assay in human lymphocytes, and an in vitro micronucleus test in human lymphocytes was previously conducted without incidence, an in vivo mammalian micronucleus test was lacking and thus, this study was performed to provide additional relevant in vivo insights into the genotoxicity of SoF1. No treatment-related adverse effects were observed and no increases in the frequencies of micronucleated immature erythrocytes (MPCEs) in male mice (5/group) at any dose level (0, 500, 1000, and 2000 mg/kg bw) of the test item by oral gavage were observed when compared with the concurrent negative and historical negative control groups. The test item did not exhibit any clastogenic or aneugenic activity in the bone marrow of mice under the applied experimental conditions.