Safety evaluation of β-agarase preparations from Streptomyces coelicolor A3(2).

Recent studies on neoagarooligosaccharides prepared by hydrolyzing agar with β-agarase DagA produced from Streptomyces coelicolor A3(2) have enhanced our knowledge about the enzymatic utility of S. coelicolor. For safety evaluation, a crude extracellular protein containing DagA (crDagA) was prepared from the culture broth of S. coelicolor A3(2) M22-2C43, a highly productive strain of DagA. All genotoxicity tests, such as bacterial reverse mutation assay, eukaryotic chromosomal aberration assay, and in vivo micronucleus assay in mice showed no mutagenic activity of crDagA. No abnormalities were found in the appearance or behavior upon single oral administration up to 20,000 mg/kg body weight (BW) [318 mg TOS (Total Organic Solids)/kg BW] and long-term repeated oral administration toxicity tests up to 10,000 mg/kg BW/day (159 mg TOS/kg BW/day) in Sprague Dawley™ rats. In addition, there were no statistically significant differences in the body weight change, food intake, hematology, blood biochemistry, organ weight, and clinical signs between the crDagA-administered and non-administered groups during the experimental period. This result showed that crDagA produced from S. coelicolor A3(2) is a safe, non-toxic substance, and therefore, can be used safely for manufacturing neoagarooligosaccharide, a functional substance effective in improving metabolic syndrome.