Lipidomic Analysis of Roseobacters of the Pelagic RCA Cluster and Their Response to Phosphorus Limitation

Abstract

The marine roseobacter-clade affiliated cluster (RCA) represents one of the most abundant groups of bacterioplankton in the global oceans, particularly in temperate and sub-polar regions. They play a key role in the biogeochemical cycling of various elements and are important players in oceanic climate-active trace gas metabolism. In contrast to copiotrophic roseobacter counterparts such as Ruegeria pomeroyi DSS-3 and Phaeobacter sp. MED193, RCA bacteria are truly pelagic and have smaller genomes. We have previously shown that RCA bacteria do not appear to encode the PlcP-mediated lipid remodeling pathway, whereby marine heterotrophic bacteria remodel their membrane lipid composition in response to phosphorus (P) stress by substituting membrane glycerophospholipids with alternative glycolipids or betaine lipids. In this study, we report lipidomic analysis of six RCA isolates. In addition to the commonly found glycerophospholipids such as phosphatidylglycerol (PG) and phosphatidylethanolamine (PE), RCA bacteria synthesize a relatively uncommon phospholipid, acylphosphatidylglycerol, which is not found in copiotrophic roseobacters. Instead, like the abundant SAR11 clade, RCA bacteria upregulate ornithine lipid biosynthesis in response to P stress, suggesting a key role of this aminolipid in the adaptation of marine heterotrophs to oceanic nutrient limitation.

An evolutionary conserved detoxification system for membrane lipid–derived peroxyl radicals in Gram-negative bacteria

“…Cells were centrifuged at 3,100 × g at 4°C and normalized to an OD 600 of 0.5. Lipids were extracted from the bacterial pellets via a modified Folch extraction method as detailed previously [ 85 ]. Before extraction, a final concentration of 500 nM of lipid standard, sphingosyl phosphatidylethanolamine (SPE; d17:1/12:0 sphingosyl PE, Avanti Polar Lipids, Birmingham, AL, USA), was added to each sample.…”

Aminolipids elicit functional trade-offs between competitiveness and bacteriophage attachment in Ruegeria pomeroyi

“…Lipid extraction from bacterial cultures was carried out using the modified Folch extraction protocol as described previously [ 20 ]. Before lipid extraction from IM and OM samples, they were spiked with d17:1/12:0 sphingosyl phosphoethanolamine (SPE) to a final concentration of 500 nM.…”

The Proteobacterial Methanotroph Methylosinus trichosporium OB3b Remodels Membrane Lipids in Response to Phosphate Limitation

“…Lipid extraction from M. trichosporium OB3b and the Δ plcP-agt mutant was carried out in three replicates using a modified Folch extraction method, as described previously ( 37 ). Briefly, 1 mL of bacterial culture (OD 540 = 0.5) was pelleted by centrifugation, and chloroform (1 mL), Milli-Q water (0.3 mL), and methanol (0.5 mL) were then added.…”