Safety assessment of Euglena gracilis ATCC 12894 whole cell biomass

Abstract

A safety assessment of the dried whole cell biomass of Euglena gracilis ATCC 12894 was performed by the bacterial reverse mutation (Ames) assay, an in vitro micronucleus assay, and a 90-day repeat oral toxicity study in Wistar rats. E. gracilis ATCC 12894 whole cell biomass has no added excipients and contains 33.8% protein, 28.8% β-glucans, 19.8% fat, 7.1% ash, and 2.8% moisture. The bacterial reverse mutation assay found no evidence of mutagenicity after exposure to E. gracilis ATCC 12894 whole cell biomass, with or without metabolic activity, at levels up to 1581 µg/plate, the limit dose for the assay. Similarly, no evidence of genotoxicity was observed in the micronucleus assay, with or without metabolic activation, up to 320 µg/mL, the limit dose for the assay. The subchronic toxicity study was performed with the following test article dose groups: 0 (control), 1250, 2500, and 5000 mg/kg/day, administered to male and female Wistar rats via oral gavage for 90 days. No test article-related mortalities or adverse events were reported during the study. Histopathological examination revealed some vacuolation in the livers of males in the 5000 mg/kg/day group. This finding was considered adaptive, due to the approximately 20% fat content of whole cell biomass, and was therefore test article-related, but not adverse. No such findings were reported in female rats in the study. The results of the subchronic toxicity study describe a no observed adverse effect level of at least 5000 mg/kg/day.