Abstract
Strain T5T is the type strain of the species Phaeobacter inhibens Martens et al. 2006, a secondary metabolite producing bacterium affiliated to the Roseobacter clade. Strain T5T was isolated from a water sample taken at the German Wadden Sea, southern North Sea. Here we describe the complete genome sequence and annotation of this bacterium with a special focus on the secondary metabolism and compare it with the genomes of the Phaeobacter inhibens strains DSM 17395 and DSM 24588 (2.10), selected because of the close phylogenetic relationship based on the 16S rRNA gene sequences of these three strains. The genome of strain T5T comprises 4,130,897 bp with 3.923 protein-coding genes and shows high similarities in genetic and genomic characteristics compared to P. inhibens DSM 17395 and DSM 24588 (2.10). Besides the chromosome, strain T5T possesses four plasmids, three of which show a high similarity to the plasmids of the strains DSM 17395 and DSM 24588 (2.10). Analysis of the fourth plasmid suggested horizontal gene transfer. Most of the genes on this plasmid are not present in the strains DSM 17395 and DSM 24588 (2.10) including a nitrous oxide reductase, which allows strain T5T a facultative anaerobic lifestyle. The G+C content was calculated from the genome sequence and differs significantly from the previously published value, thus warranting an emendation of the species description.
Highlights
Strain T5T was isolated from a water sample taken on 25th of October 1999 above an intertidal mud flat of the German Wadden Sea (53°42’20’’N, 07°43’11’’E) and found to be closely related to the type strain of Roseobacter gallaeciensis [1]
The genus Phaeobacter is known to have a high potential for secondary metabolite production, as indicated by biosynthesis of tropodithietic acid (TDA) and N-acyl homoserine lactones (AHLs), as well as presence of genes coding for polyketide synthases (PKS) and nonribosomal peptide synthetases (NRPS) [2,7,8,9,10]
The sulfur-containing TDA, for which the sulfur precursor has not yet been determined, plays an important role in the mutualistic symbioses of P. inhibens and marine algae [12]. p-Coumaric acid causes the organism to switch from a state of mutualistic symbiosis to a pathogenic lifestyle in which toxicity is mediated via the production of the algicidal roseobacticides, which, like pcoumaric, is a sulfur-containing metabolite [13,14]
Summary
Strain T5T was isolated from a water sample taken on 25th of October 1999 above an intertidal mud flat of the German Wadden Sea (53°42’20’’N, 07°43’11’’E) and found to be closely related to the type strain of Roseobacter gallaeciensis [1]. As found for various Phaeobacter strains [2,3,4,5,6,7], P. inhibens strain T5T (= DSM 16374T = LMG 22475T = CIP 109289T) is able to produce the antibiotic tropodithietic acid (TDA) [8]. Production of volatile compounds is widespread over the Roseobacter clade It displays a high proportion of volatile sulfur-containing compounds and seems to play an important role in the sulfur cycle of the ocean [11]. The sulfur-containing TDA, for which the sulfur precursor has not yet been determined, plays an important role in the mutualistic symbioses of P. inhibens and marine algae [12]. DSM 17395 and DSM 24588, originally http://standardsing enomics.org deposited as P. gallaeciensis strains, were recently reclassified as P. inhibens [15]
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