Development of a Genetic System for Marinobacter atlanticus CP1 (sp. nov.), a Wax Ester Producing Strain Isolated From an Autotrophic Biocathode.

Lina J Bird,J Fitzpatrick Doyle,Brandon J Chu,Martin H Moore,Elizabeth L Onderko,Sarah M Glaven,Anthony P Malanoski,Brian J Eddie,Brandy J Johnson,Zheng Wang,Daniel A Phillips

doi:10.3389/fmicb.2018.03176

Abstract

Here, we report on the development of a genetic system for Marinobacter sp. strain CP1, previously isolated from the Biocathode MCL community and shown to oxidize iron and grow as a cathodic biofilm. Sequence analysis of the small and large subunits of the 16S rRNA gene of CP1, as well as comparison of select conserved proteins, indicate that it is most closely related to Marinobacter adhaerens HP15 and Marinobacter sp. ES.042. In silico DNA–DNA hybridization using the genome-to-genome distance calculator (GGDC) predicts CP1 to be a new species of Marinobacter described here as Marinobacter atlanticus. CP1 is competent for transformation with plasmid DNA using conjugation with Escherichia coli donor strain WM3064 and constitutive expression of green fluorescent protein (GFP) is stable in the absence of antibiotic selection. Targeted double deletion mutagenesis of homologs for the M. aquaeoli fatty acyl-CoA reductase (acrB) and fatty aldehyde reductase (farA) genes resulted in a loss of production of wax esters; however, single deletion mutants for either gene resulted in an increase in total wax esters recovered. Genetic tools presented here for CP1 will enable further exploration of wax ester synthesis for biotechnological applications, as well as furthering our efforts to understand the role of CP1 within the Biocathode MCL community.

Highlights

Marinobacter spp. have been isolated from a wide range of ecological niches, including subsurface environments (Bonis and Gralnick, 2015; Leslie et al, 2015; Evans et al, 2018) and hydrocarbon contaminated water (Gauthier et al, 1992), and participate in important environmental processes such as biogeochemical cycling as reviewed by Singer et al (2011) and Handley and Lloyd (2013)
CP1 is a dominant member of the Biocathode MCL community, a stable microbial community enriched from seawater from the Atlantic ocean which grows and produces current on a high potential (310 vs. SHE) electrode with no added carbon
Due to the high degree of identity between the CP1 and HP15 16S and 23S rRNA genes, we further explored whether CP1 should be designated as its own species or represents a strain of M. adhaerens using in silico genome comparison

Summary

Introduction

Marinobacter spp. have been isolated from a wide range of ecological niches, including subsurface environments (Bonis and Gralnick, 2015; Leslie et al, 2015; Evans et al, 2018) and hydrocarbon contaminated water (Gauthier et al, 1992), and participate in important environmental processes such as biogeochemical cycling as reviewed by Singer et al (2011) and Handley and Lloyd (2013). Marinobacter spp. are known to produce wax esters (Barney et al, 2012; Lenneman et al, 2013), and wax ester synthesis pathways have been studied for their potential use in biotechnology applications including in the medical, food, and cosmetic industries, as well as in high-grade lubricants (Wahlen et al, 2009). Previous reports of Marinobacter adhaerens HP15 (Sonnenschein et al, 2011), M. aquaeolei VT8 (Lenneman et al, 2013), and M. subterrani (Bonis and Gralnick, 2015) have shown that this genus is genetically tractable; we developed a genetic system for CP1 in order to support efforts to understand its role in the MCL community. We provide evidence that Marinobacter sp. strain CP1 is taxonomically distinct from M. adhaerens and propose classification as a new species

Methods

Results

Discussion

Conclusion