Energy flux and membrane synthesis in photosynthetic bacteria.

Synthesis of the energy-converting membrane complex of the photosynthetic purple bacterium Rhodopseudomonas capsulata during growth under different conditions of energy flux was studied by examining the disorganizing effects of polymyxin B, with or without lysozyme, on integrity of the cell envelope. Cells growing with a limited supply of energy show an elevated bacteriochlorophyll content and increased resistance to breakdown of the "permeability barrier" by these agents. It seems that purple bacteria respond to energy restriction by preferentially synthesizing excess bacteriochlorophyll-membrane which, in effect, toughens the cell integument.