Genome Analysis of Vallitalea guaymasensis Strain L81 Isolated from a Deep-Sea Hydrothermal Vent System.

Anders Schouw,Runar Stokke,Francesca Vulcano,Ida Helene Steen,Irene Roalkvam,William Peter Hocking,Eoghan Reeves,Gunhild Bødtker

doi:10.3390/microorganisms6030063

Anders Schouw, Runar Stokke + Show 6 more

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https://doi.org/10.3390/microorganisms6030063

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Journal: Microorganisms	Publication Date: Jul 4, 2018
Citations: 11	License type: CC BY 4.0

Affiliation: University of Bergen, Uni Research (Norway)

Abstract

Abyssivirga alkaniphila strain L81T, recently isolated from a black smoker biofilm at the Loki’s Castle hydrothermal vent field, was previously described as a mesophilic, obligately anaerobic heterotroph able to ferment carbohydrates, peptides, and aliphatic hydrocarbons. The strain was classified as a new genus within the family Lachnospiraceae. Herein, its genome is analyzed and A. alkaniphila is reassigned to the genus Vallitalea as a new strain of V. guaymasensis, designated V. guaymasensis strain L81. The 6.4 Mbp genome contained 5651 protein encoding genes, whereof 4043 were given a functional prediction. Pathways for fermentation of mono-saccharides, di-saccharides, peptides, and amino acids were identified whereas a complete pathway for the fermentation of n-alkanes was not found. Growth on carbohydrates and proteinous compounds supported methane production in co-cultures with Methanoplanus limicola. Multiple confurcating hydrogen-producing hydrogenases, a putative bifurcating electron-transferring flavoprotein—butyryl-CoA dehydrogenase complex, and a Rnf-complex form a basis for the observed hydrogen-production and a putative reverse electron-transport in V. guaymasensis strain L81. Combined with the observation that n-alkanes did not support growth in co-cultures with M. limicola, it seemed more plausible that the previously observed degradation patterns of crude-oil in strain L81 are explained by unspecific activation and may represent a detoxification mechanism, representing an interesting ecological function. Genes encoding a capacity for polyketide synthesis, prophages, and resistance to antibiotics shows interactions with the co-occurring microorganisms. This study enlightens the function of the fermentative microorganisms from hydrothermal vents systems and adds valuable information on the bioprospecting potential emerging in deep-sea hydrothermal systems.

Highlights

In hydrothermal vent systems water-rock reactions produce microbial nutrients such as H2S, CH4 and H2, which create the basis for chemosynthetic food-webs and allow hot spots for biological activity to form in the deep ocean
A DNA-DNA hybridization was performed of A. alkaniphila L81T with V. guaymasensis RA1766G1T and V. pronyensis, respectively
The results revealed a similarity between A. alkaniphila L81T and V. guaymasensis of 69.7% and with V. pronyensis of 13.35%

Summary

Introduction

In hydrothermal vent systems water-rock reactions produce microbial nutrients such as H2S, CH4 and H2, which create the basis for chemosynthetic food-webs and allow hot spots for biological activity to form in the deep ocean. This primary production results in a steady supply of organic matter that may be utilized by heterotrophic microorganisms [1,2,3]. The high-temperature vent fluids have high concentrations of CH4, H2, and CO2, with CH4 values of 15.5 mmol kg−1, among the highest reported for a bare-rock hosted field [5]. The microbial mats growing on the black smokers in LCVF are dominated by chemolitoautotrophic Epsilonproteobacteria [3,9] supporting growth of heterotrophic Bacteroidetes [10,11]

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