title: Diversity and antimicrobial potential of bacterial isolates associated with the soft coral Alcyonium digitatum from the Baltic Sea.
abstract: It is well recognized that microorganisms associated with marine invertebrates, in particular sponges and hard corals, are an excellent source of new natural products. Therefore, the diversity of bacteria associated with marine invertebrates and their potential to produce bioactive compounds have received much attention in recent years. We report here for the first time on the biodiversity of bacteria associated with the soft coral Alcyonium digitatum, which is abundant in the Baltic Sea. In order to increase the cultured diversity, bacteria were isolated using four different media, identified with support of 16S rRNA gene sequences and screened for antimicrobial activity using two different media. Activity of crude extracts was tested against Bacillus subtilis, Staphylococcus epidermidis, Escherichia coli, and the yeast Candida albicans. A total of 251 coral-associated bacterial isolates were classified and found to belong to 41 species in 14 genera of the Firmicutes, Actinobacteria, Gammaproteobacteria, and Alphaproteobacteria. The genus Bacillus was most abundant and diverse with 17 recognized species. Forty-eight percent of all 251 isolates exhibited antimicrobial activity. All isolates of Bacillus methylotrophicus and Bacillus amyloliquefaciens displayed inhibition of at least three out of the four tested microorganisms. It became obvious during this study that the production of antibiotic substances not only is strain-specific, but in many cases also depends on the media composition and growth conditions. In addition, the antimicrobial potential of bacteria associated with A. digitatum may represent a promising source for antimicrobial substances.
authors.affiliation: Department of Marine Microbiology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105, Kiel, Germany.|Department of Marine Ecology, Institute of Oceanography, 01 Cau Da, Nha Trang, Khanh Hoa, Vietnam.
authors.forename: Thi Mien
authors.initials: TM
authors.lastname: Pham
authors.affiliation: Department of Marine Microbiology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105, Kiel, Germany.
authors.forename: Jutta
authors.initials: J
authors.lastname: Wiese
authors.affiliation: Department of Marine Microbiology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105, Kiel, Germany.
authors.forename: Arlette
authors.initials: A
authors.lastname: Wenzel-Storjohann
authors.affiliation: Department of Marine Microbiology, GEOMAR Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg 20, 24105, Kiel, Germany. jimhoff@geomar.de.
authors.forename: Johannes F
authors.initials: JF
authors.lastname: Imhoff
mesh_terms: D039903:Actinobacteria / Q000145:classification / Q000302:isolation & purification; D020561:Alphaproteobacteria / Q000145:classification / Q000302:isolation & purification; D000818:Animals; D037421:Anthozoa / Q000382:microbiology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000898:Antibiosis; D001407:Bacillus / Q000145:classification / Q000302:isolation & purification; D001419:Bacteria / Q000145:classification* / Q000302:isolation & purification*; D044822:Biodiversity; D020563:Gammaproteobacteria / Q000145:classification / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D012336:RNA, Ribosomal, 16S
keywords: Antimicrobial activity; Associated bacteria; Bacterial diversity; Soft coral Alcyonium digitatum