American Society for Microbiology, Applied and Environmental Microbiology, 5(79), p. 1598-1605, 2013
DOI: 10.1128/aem.03354-12
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ABSTRACT Microbes associated with marine sponges are considered important producers of bioactive, structurally unique polyketides. The synthesis of such secondary metabolites involves type I polyketide synthases (PKSs), which are enzymes that reach a maximum complexity degree in bacteria. The Haplosclerida sponge Arenosclera brasiliensis hosts a complex microbiota and is the source of arenosclerins, alkaloids with cytotoxic and antibacterial activity. In the present investigation, we performed high-throughput sequencing of the ketosynthase (KS) amplicon to investigate the diversity of PKS genes present in the metagenome of A. brasiliensis . Almost 4,000 ketosynthase reads were recovered, with about 90% annotated automatically as bacterial. A total of 235 bacterial KS contigs was rigorously assembled from this sequence pool and submitted to phylogenetic analysis. A great diversity of six type I PKS groups has been consistently detected in our phylogenetic reconstructions, including a novel and A. brasiliensis -exclusive group. Our study is the first to reveal the diversity of type I PKS genes in A. brasiliensis as well as the potential of its microbiome to serve as a source of new polyketides.