Ebosin, a novel exopolysaccharide produced by Streptomyces sp. 139, has obvious antirheumatic arthritis activity in vivo, and its biosynthesis gene cluster (ste), consisting of 27 open reading frames, has been identified. This paper reports our study of the gene functionality of ste8, the predicted protein product of which is homologous to some bacterial chain length determinant Wzz proteins. For characterization of Ste8, ste8 was cloned and expressed in the mutant strain E. coli 086:H2 (∆wzz). The functional complementation of wzz by ste8 was demonstrated by the restoration of wild-type lipopolysaccharide biosynthesis and increased levels of serum resistance of E. coli 086:H2 (∆wzz) (pET30a-ste8). To examine the function of ste8 in ebosin biosynthesis, the gene was knocked out with a double crossover via homologous recombination. The molecular weight of the ebosin derivative EPS-8m produced by the mutant Streptomyces sp. 139 (ste8-) was much lower than that of ebosin, and the binding activity of EPS-8m for IL-1R decreased significantly compared with ebosin. These results demonstrate that ste8 encodes a chain length determinant (Wzz) that functions in ebosin biosynthesis.
Heavy ion irradiation induced mutation is a unique method of physical mutation, with various parameters, high LET and RBE characteristic. The spore suspension of streptomyces avermitilis were irradiated by carbon ions with doses of 0、30、40、50、60 and 70 Gy. The high avermectin producing strain was successfully obtained after the mutagenesis processing by heavy ion beam and the screening of orthomutation strains. Two strains(No.203 and No.148) which potency was 5200μg/ml was sieved and its potency increased 38.64% than the original strain. The obtained strains were used for 1 ton fermentation tank and the pilot 5-ton fermentation tank amplification tests.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.