Atlantic microbial membranes change with scarce phosphorus
A peer-reviewed survey of Atlantic Ocean datasets links changes in microbial membrane chemistry to phosphate availability. Lipids carried a larger carbon-to-phosphorus ratio in phosphorus-poor waters, including the Sargasso Sea. The analysis also found that candidate molecular signs of nutrient stress did not agree everywhere, reflecting both microbial adjustment and differences in the communities sampled across the basin.
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Membrane chemistry across the ocean
Microbial membrane lipids changed their elemental composition with nutrient availability across the western Atlantic Ocean. A peer-reviewed Nature Communications analysis combined published measurements of lipids, nutrients and suspended organic matter along cruises between latitudes near 40 degrees south and 55 degrees north. Lipids contain carbon and can also carry phosphorus, nitrogen or sulfur, linking the membranes around microbial cells to ocean nutrient cycles.[1]
A stronger relationship with phosphate
Lipid carbon-to-phosphorus ratios were high in phosphorus-poor waters such as the Sargasso Sea in the North Atlantic. At community scale, phosphate had a stronger relationship with lipid composition than dissolved inorganic nitrogen. Microbes can replace phosphorus-bearing lipid headgroups with alternatives when phosphorus is scarce, although different species also make different lipids. Changes along the cruises therefore combine physiological adjustment with shifts in community membership.[1]
Comparing lipids with suspended particles
A paired North Atlantic dataset contained 128 surface samples with both lipid and bulk particulate measurements. On average, membrane lipids accounted for 8.2 percent of the particles’ carbon. Their contributions were 10.2 percent for phosphorus and 1.1 percent for nitrogen. The carbon-to-phosphorus ratio in lipids tracked changes in the overall particles, but proposed molecular markers of nutrient stress did not agree uniformly. Their interpretation depends on the organisms present and the particular nutrient conditions.[1]
