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Biological and Chemical Diversity of Bacteria Associated with a Marine Flatworm

1,2,†, 1,3,†, 4,5, 6, 7 and 1,*
Shenzhen Key Laboratory of Marine Bioresource & Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
School of Life Sciences, Xiamen University, Xiamen 361102, China
Key Laboratory of Marine Drugs, Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
The Eighth Affiliated Hospital, Sun Yat-sen University, Shenzhen 518033, China
Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou 510632, China
Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
HEC Research and Development Center, HEC Pharm Group, Dongguan 523871, China
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Mar. Drugs 2017, 15(9), 281;
Received: 20 July 2017 / Revised: 21 August 2017 / Accepted: 29 August 2017 / Published: 1 September 2017
(This article belongs to the Special Issue Bioactive Compounds from Marine Microbes - II)
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The aim of this research is to explore the biological and chemical diversity of bacteria associated with a marine flatworm Paraplanocera 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 Streptomyces sp. XY-FW47 fermentation broth showed strong antibacterial activity against methicillin-resistant Staphylococcus aureus 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, EC50 = 1.12 μg/mL) and antifungal (Setosphaeria turcica MIC = 2.40 μg/mL) activities. Their structure–activity relationship (SAR) was also preliminarily discussed in this study. View Full-Text
Keywords: marine flatworm; natural products; bacteria; Paraplanocera sp.; Streptomyces sp.; geldanamycin marine flatworm; natural products; bacteria; Paraplanocera sp.; Streptomyces sp.; geldanamycin

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Lin, H.-N.; Wang, K.-L.; Wu, Z.-H.; Tian, R.-M.; Liu, G.-Z.; Xu, Y. Biological and Chemical Diversity of Bacteria Associated with a Marine Flatworm. Mar. Drugs 2017, 15, 281.

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