Isolation and Identification of an Anthracimycin Analogue from <i>Nocardiopsis kunsanensis</i>, a Halophile from a Saltern, by Genomic Mining Strategy

Abstract

Modern medicine is unthinkable without antibiotics; yet, growing issues with microbial drug resistance require intensified search for new active compounds. Natural products generated by Actinobacteria have been a rich source of candidate antibiotics, for example anthracimycin that, so far, is only known to be produced by <i>Streptomyces</i> species. Based on sequence similarity with the respective biosynthetic cluster, we sifted through available microbial genome data with the goal to find alternative anthracimycin-producing organisms. In this work, we report about the prediction and experimental verification of the production of anthracimycin derivatives by <i>Nocardiopsis kunsanensis</i>, a non-<i>Streptomyces</i> actinobacterial microorganism. We discovered <i>N. kunsanensis</i> to predominantly produce a new anthracimycin derivative with methyl group at C-8 and none at C-2, labeled anthracimycin BII-2619, besides a minor amount of anthracimycin. It displays activity against Gram-positive bacteria with similar low level of mammalian cytotoxicity as that of anthracimycin.