Labilibaculum manganireducens gen. nov., sp. nov. and Labilibaculum filiforme sp. nov., Novel Bacteroidetes Isolated from Subsurface Sediments of the Baltic Sea.

Verona Vandieken,Bert Engelen,Heribert Cypionka,Helge Niemann,Ian P G Marshall

doi:10.3389/fmicb.2017.02614

Abstract

Microbial communities in deep subsurface sediments are challenged by the decrease in amount and quality of organic substrates with depth. In sediments of the Baltic Sea, they might additionally have to cope with an increase in salinity from ions that have diffused downward from the overlying water during the last 9000 years. Here, we report the isolation and characterization of four novel bacteria of the Bacteroidetes from depths of 14–52 m below seafloor (mbsf) of Baltic Sea sediments sampled during International Ocean Discovery Program (IODP) Expedition 347. Based on physiological, chemotaxonomic and genotypic characterization, we propose that the four strains represent two new species within a new genus in the family Marinifilaceae, with the proposed names Labilibaculum manganireducens gen. nov., sp. nov. (type strain 59.10-2MT) and Labilibaculum filiforme sp. nov. (type strains 59.16BT) with additional strains of this species (59.10-1M and 60.6M). The draft genomes of the two type strains had sizes of 5.2 and 5.3 Mb and reflected the major physiological capabilities. The strains showed gliding motility, were psychrotolerant, neutrophilic and halotolerant. Growth by fermentation of mono- and disaccharides as well as pyruvate, lactate and glycerol was observed. During glucose fermentation, small amounts of electron equivalents were transferred to Fe(III) by all strains, while one of the strains also reduced Mn(IV). Thereby, the four strains broaden the phylogenetic range of prokaryotes known to reduce metals to the group of Bacteroidetes. Halotolerance and metal reduction might both be beneficial for survival in deep subsurface sediments of the Baltic Sea.

Highlights

Bacteroidetes are globally distributed and abundant in diverse environments from very energy-rich animals’ guts to the most energy-limited habitats of our planet such as deep subsurface sediments, the deep biosphere (e.g., Biddle et al, 2008; Ley et al, 2008; Orsi et al, 2013; Inagaki et al, 2015)
We report the isolation and characterization of four novel bacteria of the Bacteroidetes from depths of 14–52 m below seafloor of Baltic Sea sediments sampled during International Ocean Discovery Program (IODP) Expedition 347
As oxygen is depleted within the uppermost sediment layers, fermentation becomes important for the breakdown of the recalcitrant organic material

Summary

Introduction

Bacteroidetes are globally distributed and abundant in diverse environments from very energy-rich animals’ guts to the most energy-limited habitats of our planet such as deep subsurface sediments, the deep biosphere (e.g., Biddle et al, 2008; Ley et al, 2008; Orsi et al, 2013; Inagaki et al, 2015). In the latter, microbes are cut off from the carbon supply of the water column as they are slowly buried in the sediment. It can be speculated that this still provides a competitive advantage for the fermenters of the deep biosphere which have to live on the scarce carbon sources present

Objectives

Methods

Results