Biological and Chemical Diversity of Bacteria Associated with a Marine Flatworm

• Published in: Marine drugs Vol. 15; no. 9; p. 281
• Main Authors: Lin, Hui-Na, Wang, Kai-Ling, Wu, Ze-Hong, Tian, Ren-Mao, Liu, Guo-Zhu, Xu, Ying
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.09.2017; MDPI
• Subjects: Acetates; Acetic acid; Actinobacteria - chemistry; Actinobacteria - genetics; Actinomycetes; Analogs; Animals; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Antifungal activity; Antifungal Agents - pharmacology; Aquatic invertebrates; Bacteria; Benzoquinones - metabolism; Bioactive compounds; Biodiversity; Biological activity; Cytotoxicity; Drug resistance; Ethyl acetate; Fermentation; Fungicides; Geldanamycin; Geologic Sediments - microbiology; HeLa Cells; Humans; Lactams, Macrocyclic - metabolism; Liquid chromatography; Marine Biology; marine flatworm; Mass spectrometry; Mass spectroscopy; Metabolites; Methicillin; Methicillin-Resistant Staphylococcus aureus - drug effects; Microbial Sensitivity Tests; Microbiological strains; Minimum inhibitory concentration; natural products; Paraplanocera sp; Platyhelminths - microbiology; SAR (radar); Screening; Spectral analysis; Staphylococcus aureus; Staphylococcus infections; Strains (organisms); Streptomyces - chemistry; Streptomyces sp; Structure-Activity Relationship; natural products; marine flatworm; bacteria; Streptomyces sp; geldanamycin; Paraplanocera sp
• ISSN: 1660-3397; 1660-3397
• DOI: 10.3390/md15090281

The aim of this research is to explore the biological and chemical diversity of bacteria associated with a marine flatworm sp., and to discover the bioactive metabolites from culturable strains. A total of 141 strains of bacteria including 45 strains of actinomycetes and 96 strains of other bacteria were isolated, identified and fermented on a small scale. Bioactive screening (antibacterial and cytotoxic activities) and chemical screening (ultra-performance liquid chromatography-mass spectrometry (UPLC-MS)) yielded several target bacterial strains. Among these strains, the ethyl acetate (EA) crude extract of sp. XY-FW47 fermentation broth showed strong antibacterial activity against methicillin-resistant ATCC43300 (MRSA ATCC43300) and potent cytotoxic effects on HeLa cells. The UPLC-MS spectral analysis of the crude extract indicated that the strain XY-FW47 could produce a series of geldanamycins (GMs). One new geldanamycin (GM) analog, 4,5-dihydro-17-O-demethylgeldanamycin (1), and three known GMs (2-4) were obtained. All of these compounds were tested for antibacterial, cytotoxic, and antifungal activities, yet only GM (3) showed potent cytotoxic (HeLa cells, EC = 1.12 μg/mL) and antifungal ( MIC = 2.40 μg/mL) activities. Their structure-activity relationship (SAR) was also preliminarily discussed in this study.