Genomics-Driven Discovery of Benzoxazole Alkaloids from the Marine-Derived Micromonospora sp. SCSIO 07395.

Benzoxazole alkaloids exhibit a diverse array of structures and interesting biological activities. Herein we report the identification of a benzoxazole alkaloid-encoding biosynthetic gene cluster ( mich BGC) in the marine-derived actinomycete Micromonospora sp. SCSIO 07395 and the heterologous expression of this BGC in Streptomyces albus . This approach led to the discovery of five new benzoxazole alkaloids microechmycin A-E ( 1 - 5 ), and a previously synthesized compound 6 . Their structures were elucidated by HRESIMS and 1D and 2D NMR data. Microechmycin A (1) showed moderate antibacterial activity against Micrococcus luteus SCSIO ML01 with the minimal inhibitory concentration (MIC) value of 8 μg mL -1 .