Heterologous coexpression of Vitreoscilla hemoglobin and Bacillusmegaterium glucanase in Streptomyces lydicus A02 enhanced its production

Huiling Wu, Jinjin Li, Dan Dong, Ting Liu, Taotao Zhang, Dianpeng Zhang, Weicheng Liu.

Enzyme and Microbial Technology 81 (2015) 80–87

Streptomyces lydicus A02 is a novel producer of commercially important polyene macrocyclic antibioticnatamycin and a potential biocontrol agent to several plant fungal diseases, including wilt caused byFusarium oxysporum f. spp. To improve the natamycin production and the antifungal activity of S. lydicusA02, we coexpressed gene vgb encoding Vitreoscilla hemoglobin (VHb) and bglC encoding Bacillus mega-terium L103 glucanase, both under the control of the strong constitutive ermE* promoter, in S. lydicusA02. Our results showed that coexpressing VHb and glucanase improved cell growth, and the engineeredstrain produced 26.90% more biomass than the wild-type strain after 72 h fermentation in YSG medium.In addition, coexpressing genes encoding VHb and glucanase led to increased natamycin production,higher endogenous chitinase activity and exogenous glucanase activity, as well as enhanced antifungalactivity in the engineered S. lydicus AVG02 and AGV02, regardless of the position of the two genes on theplasmids. Compared with model strains, few reports have successfully coexpressed VHb and other for-eign proteins in industrial strains. Our results illustrated an effective approach for improving antifungalactivity in an industrial strain by the rational engineering of combined favorable factors.