Differences in Survivability under Starvation Conditions Among Four Species of Purple Nonsulfur Phototrophic Bacteria

Abstract

Survivability under carbon-starvation conditions was investigated in four species of purple phototrophic bacteria: Rhodopseudomonas palustris, Rhodobacter sphaeroides, Rhodospirillum rubrum, and Rubrivivax gelatinosus. All these test organisms survived longer in the light than in the dark. ATP levels in the cultures were maintained in the light, which indicated that survivability was supported by photosynthesis. Survivability and tolerance against hypertonic stress in the dark was higher in Rhodopseudomonas palustris, which is widely distributed in natural environments including soils, than in the three other species.

Anoxygenic Photosynthesis —A Photochemical Reaction That Does Not Contribute to Oxygen Reproduction—

“…These features may be advantageous to AAnP bacteria and, thus, they may outcompete other non-phototrophs in oligotrophic environments. A similar increase in viability by illumination has been reported in anoxygenic phototrophic bacteria such as Rhodopseudomonas palustris ( 5 , 8 ). AAnP bacteria that do not produce oxygen or fix carbon dioxide do not appear to contribute to the global ecosystem.…”

Bacterial Survival under Extreme UV Radiation: A Comparative Proteomics Study of Rhodobacter sp., Isolated from High Altitude Wetlands in Chile

“…It has been reported that purple non-sulfur bacteria under starvation stress support a longer survival by maintaining ATP levels in the cultures using photosynthesis, compared to cultures with a decreased viability in dark conditions (Kanno et al, 2014). Although we identified proteins involved in photosystem (PS) regulation such as the photosynthetic apparatus regulatory protein RegA (RH1_01792) in artificial and natural light treatments, we did not quantify proteins related to photosynthetic complexes in our study.…”

Survivability of Microbes in Natural Environments and Their Ecological Impacts

“…Koenig et al indicated an energy requirement for response to stresses, because bacterial cells under lower energy-producing conditions were more sensitive to toxic solvents ( 18 ). In contrast, photosynthetic energy production in the light increased the viability of photosynthetic bacteria under nutrient-limited conditions ( 7 , 15 , 35 ). Through the action of proteorhodopsin, a light-driven proton pump, light energy is also converted to chemical energy required for starvation survival ( 1 , 6 ).…”