Conference Proceeding

Isolation of halichrome A from a Metagenomic Library Derived from the Marine Sponge Halichondria okadai

Mr. Takahiro Abe,
In the ocean, many structurally unique compounds that have significant biological activities have been isolated from various marine invertebrates. Especially, sponges, belonging to the porifera, are also isolated many natural products. Recent research suggests that many marine sponges harbor various microbial symbionts, by which many bioactive compounds are produced, and that the number of cultivable bacteria represents 1% or fewer of the total environmental bacteria. So, to take advantage of sponge symbionts efficiently, the metagenomic analysis is optimal as culture independent analysis technique. In this study, we isolate metagenomic DNA from bacterial symbionts of Japanese marine sponge, H. okadai, and isolated a pigment from a metagenomic library. Marine sponge, H. okadai, was crushed with buffer and separated by centrifuge and the genomic DNA was extracted from bacteria fraction. Firstly, metagenomic DNA was ligated into fosmid vector pCC1FOS vector (Epicentre) and the ligated vectors were transformed into E. coli EPI300 (Epicentre). The transformants were spread onto LB medium. A total of 150000 fosmid clones metagenomic library were constructed. Then, isolated genomic DNA was ligated into BAC vector pCC1BAC (Epicentre) and the ligated vectors were transformed into E. coli EPI100. Constructed fosmid library derived from H. okadai, was screened for pigment production to obtain several active clones. Then, tinted clones were screened and the compound was purified from culture broth of clone by several chromatography steps to afford single isolated compound. We clarified that yellow pigment shows moderate cytotoxicity to B16 cell. We isolated the novel pigment halichrome A, which was determined to be a biindole, and which exhibited cytotoxicity against B16 melanoma cells.

Published: 28 July 2017

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Copyright: © 2017 Takahiro Abe. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.