Dynamics of Metabolic Activities and Gene Expression in the Roseobacter Clade Bacterium Phaeobacter sp. Strain MED193 during Growth with Thiosulfate

Abstract

bMetagenomic analyses of surface seawater reveal that genes for sulfur oxidation are widespread in bacterioplankton communities. However, little is known about the metabolic processes used to exploit the energy potentially gained from inorganic sulfur oxidation in oxic seawater. We therefore studied the sox gene system containing Roseobacter clade isolate Phaeobacter sp. strain MED193 in acetate minimal medium with and without thiosulfate. The addition of thiosulfate enhanced the bacterial growth yields up to 40% in this strain. Concomitantly, soxB and soxY gene expression increased about 8-fold with thiosulfate and remained 11-fold higher than that in controls through stationary phase. At stationary phase, thiosulfate stimulated protein synthesis and anaplerotic CO 2 fixation rates up to 5-and 35-fold, respectively. Several genes involved in anaplerotic CO 2 fixation (i.e., pyruvate carboxylase, propionyl coenzyme A [CoA], and crotonyl-CoA carboxylase) were highly expressed during active growth, coinciding with high CO 2 fixation rates. The high expression of key genes in the ethylmalonyl-CoA pathway suggests that this is an important pathway for the utilization of two-carbon compounds in Phaeobacter sp. MED193. Overall, our findings imply that Roseobacter clade bacteria carrying sox genes can use their lithotrophic potential to gain additional energy from sulfur oxidation for both increasing their growth capacity and improving their long-term survival.

Characterisation of Non-Autoinducing Tropodithietic Acid (TDA) Production from Marine Sponge Pseudovibrio Species

“…Quantitative real time-PCR signals were normalized to the constitutively expressed housekeeping gene gyrB . This gene was chosen on the basis that it is universally used for normalization of gene expression data in a broad spectrum of microbial species [ 47 , 48 ].…”

Microbial Surface Colonization and Biofilm Development in Marine Environments

“…Some MRC bacteria synthesize and store poly-␤-hydroxyalkanoates when carbon and energy resources are available but inorganic nutrients are limiting (781,782), which may enhance bacterial viability via poly-␤-hydroxyalkanoate catabolism when other sources of organic substrates are scarce (594). Some MRC bacteria also carry out lithotrophic sulfur oxidation to conserve additional energy (783,784), which may be explored to enhance anaplerotic CO 2 fixation, growth, and survival (761,785). These traits provide MRC bacteria with additional competitive advantages for energy acquisition, energy conservation, and stabilization of bacterium-alga and bacteriumsurface associations.…”

Ecophysiology of the Cosmopolitan OM252 Bacterioplankton ( Gammaproteobacteria )

“…More recently, we have also learned that sox genes are common in the oxic marine water column ( 53 , 62 , 63 ). Indeed, many marine prokaryotes contain these genes, and thiosulfate oxidation can be used to stimulate growth under mixotrophic conditions and even anapleurotic carbon fixation (see, for example, references 64 – 67 ). Thus, a variety of microorganisms from oxic marine waters are poised for thiosulfate-based chemolithotrophy and sometimes autotrophy.…”