Antifouling diketopiperazines produced by a deep-sea bacterium, Streptomyces fungicidicus

Xiancui Li, Sergey Dobretsov, Ying Xu, Xiang Xiao, Oi Hung, Pei Yuan Qian*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

89 Citations (Scopus)


Modern antifouling coatings use heavy metals and toxic organic molecules to prevent biofouling, the undesirable growth of marine organisms on man-made substrata. In an ongoing survey of deep-sea microorganisms aimed at finding low toxic antifouling metabolites, an actinomycete bacterium was isolated from the Pacific sediment at the depth of about 5000 m. The bacterium was closely related to Streptomyces fungicidicus (99% similarity) according to 16S ribosomal RNA sequence information. The spent culture medium of this bacterium inhibited barnacle larval attachment. Bioassay-guided fractionation was employed to isolate antifouling compounds. The ethyl acetate extract was fractionated by using an open silica gel column. Active fractions were further purified on a HPLC C 18 column. Five diketopiperazines, cyclo-(L-Leu-L-Pro), cyclo-(L-Phe-L-Pro), cyclo-(L-Val-L-Pro), cyclo-(L-Trp-L-Pro), and cyclo-(L-Leu-L-Val) were isolated for the first time from a deep sea bacterium, and the structures of the compounds were elucidated by nuclear magnetic resonance spectroscopy and mass spectrometry. The pure diketopiperazines were tested for antilarval activity using the barnacle Balanus amphitrite . Effective concentrations that inhibited 50% larval attachment (EC 50 ) after 24 h ranged from 0.10 - 0.27 mM. The data suggest that diketopiperazines and other compounds from deep-sea bacteria may be used as novel antifoulants.

Original languageEnglish
Pages (from-to)187-194
Number of pages8
Issue number3
Publication statusPublished - Jan 1 2006
Externally publishedYes


  • Antifouling products
  • Deep-sea bacteria
  • Diketopiperazines
  • Streptomyces fungicidicus

ASJC Scopus subject areas

  • Aquatic Science
  • Applied Microbiology and Biotechnology
  • Water Science and Technology


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