Formation of Gas Vesicles in Phosphorus-limited Cultures of Microcystis aeruginosa

Abstract

SUMMARY: The formation of gas vesicles in samples taken from phosphorus-limited cultures of Microcystis aeruginosa was studied after a phosphate pulse. A light period of at least 10 h after the pulse was needed before gas vesicles were synthesized de novo, and formation did not occur in the dark. The length of the light period correlated with the increase in gas vacuolation. When samples were subjected to 5 h light periods at different times after the addition of phosphate, formation of gas vesicles was only observed when the light period started at least 5 h after the addition of phosphate. Gas vesicle formation was saturated at a photon flux density of approximately 50 μmol m-2 s-1. Synthesis of gas vesicles was not detected when the cultures were treated with chloramphenicol, rifampicin or 3-(3,4-dichlorophenyl)-N, N'-dimethylurea (DCMU); total gas vesicle volume did not decrease under these conditions, suggesting that turnover of gas vesicles occurs very slowly, if at all.