title: Metagenomic sequencing of marine periphyton: taxonomic and functional insights into biofilm communities.
abstract: Periphyton communities are complex phototrophic, multispecies biofilms that develop on surfaces in aquatic environments. These communities harbor a large diversity of organisms comprising viruses, bacteria, algae, fungi, protozoans, and metazoans. However, thus far the total biodiversity of periphyton has not been described. In this study, we use metagenomics to characterize periphyton communities from the marine environment of the Swedish west coast. Although we found approximately ten times more eukaryotic rRNA marker gene sequences compared to prokaryotic, the whole metagenome-based similarity searches showed that bacteria constitute the most abundant phyla in these biofilms. We show that marine periphyton encompass a range of heterotrophic and phototrophic organisms. Heterotrophic bacteria, including the majority of proteobacterial clades and Bacteroidetes, and eukaryotic macro-invertebrates were found to dominate periphyton. The phototrophic groups comprise Cyanobacteria and the alpha-proteobacterial genus Roseobacter, followed by different micro- and macro-algae. We also assess the metabolic pathways that predispose these communities to an attached lifestyle. Functional indicators of the biofilm form of life in periphyton involve genes coding for enzymes that catalyze the production and degradation of extracellular polymeric substances, mainly in the form of complex sugars such as starch and glycogen-like meshes together with chitin. Genes for 278 different transporter proteins were detected in the metagenome, constituting the most abundant protein complexes. Finally, genes encoding enzymes that participate in anaerobic pathways, such as denitrification and methanogenesis, were detected suggesting the presence of anaerobic or low-oxygen micro-zones within the biofilms.
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg Gothenburg, Sweden.
authors.forename: Kemal
authors.initials: K
authors.lastname: Sanli
authors.affiliation: Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg Gothenburg, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Bengtsson-Palme
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg Gothenburg, Sweden.
authors.forename: R Henrik
authors.initials: RH
authors.lastname: Nilsson
authors.affiliation: Department of Mathematical Sciences, Chalmers University of Technology Gothenburg, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Kristiansson
authors.affiliation: Department of Chemistry and Molecular Biology, University of Gothenburg Gothenburg, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Alm Rosenblad
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg Gothenburg, Sweden.
authors.forename: Hans
authors.initials: H
authors.lastname: Blanck
authors.affiliation: Department of Shipping and Marine Technology, Chalmers University of Technology Gothenburg, Sweden.
authors.forename: Karl M
authors.initials: KM
authors.lastname: Eriksson
keywords: biodiversity; biofouling; marine biofilms; microbial ecology; next generation sequencing; pathway analysis; shotgun metagenomics; shotgun sequencing