Membranal phosphatidylglycerol enhances oxygen diffusion and release from cyanobacteria

Abstract

Efficient oxygen transfer is critical challenge in algae-bacteria consortia, where aerobic bacteria depend on oxygen supplied by algae for the degradation of organic pollutants. Despite the well-documented role of cyanobacterial photosynthesis in oxygen production, the mechanisms regulating oxygen diffusion and release remain poorly understood. This study investigates the abiological functions of phosphatidylglycerol (PG), a key membrane phospholipid, in modulating oxygen dynamics in Synechococcus elongates. By engineering a PG-enriched pgsA mutant strain, we observed significantly enhanced oxygen diffusion and bubble release compared to the wild-type strain. Molecular dynamics simulations revealed that PG enrichment lowers energy barriers and increases the rate of oxygen permeation across the cell membrane. Single-cell adhesion measurements using atomic force microscopy demonstrated reduced cell-bubble adhesion forces in the pgsA strain, promoting efficient oxygen bubble detachment. PG incorporation also reduced surface roughness, decreased envelope stiffness, and enhanced membrane hydrophilicity, further supporting oxygen release. Importantly, PG enrichment did not affect photosynthetic efficiency or cell growth, indicating that the observed enhancements are driven by PG's abiological functions. These findings provide new insights into the role of membrane lipids in cyanobacterial oxygen dynamics and highlight PG's potential for improving oxygen delivery in environmental applications such as wastewater treatment and aquatic ecosystem restoration.