Complete Genome Sequence, Biological Activities, and Metabolomic Profiles of Mangrove-Derived Streptomyces sp. SM1P

The genome of Streptomyces sp. SM1P was sequenced to give a contig of 7,561,428 bp (71.7% G + C content) and 24 putative secondary metabolite biosynthetic gene clusters (BGCs). Eight of the BGCs showed high similarity (≥ 80%), three have moderate similarity (between 50 and 79%), and eleven showed low similarity (less than 50%) to known BGCs. The strain was cultivated in 7 different media prepared in 3 different solvents and the secondary metabolites were extracted with ethyl acetate to give 21 different extracts. All extracts showed antimicrobial and cytotoxic activities, with extracts from the ISP1/NaCl and ISP4/ASW cultures were the most active against bacteria and brine shrimp nauplii, respectively. The extract of the ISP2/NaCl culture, which gave a high number of spots on TLC, was also active against Plasmodium berghei. Untargeted metabolomic analysis of the ISP1/NaCl, ISP2/NaCl, and ISP4/ASW extracts using gas chromatography-mass spectrometry (GC-MS) and comparisons of the data against the National Institute of Standards and Technology 20 Mass Spectral Library showed variations between their secondary metabolites. Principal Component Analysis of the m/z values showed a correlation between ISP1/NaCl and ISP2/NaCl but not with ISP4/ASW. Metabolomic analysis of ISP2/NaCl extract using liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) and comparisons of the data with those in the GNPS database and others indicated the presence of a lankamycin derivative (an antibiotic) and a cyclosporin derivative (an immunosuppressant). However, many other metabolites did not have a match. The results showed that Streptomyces sp. SM1P has potential as a producer of new secondary metabolites, particularly those with antimicrobial and antitumor activities.