Abstract

Flow cytometry’s (FCM) measurement of membrane potential (MP) and cell respiration viability based on continuous culture was used to investigate the responses of aerobic anoxygenic phototrophic bacteria (AAPB) in the heterotrophic growth and regulation mechanism of photosynthesis to environmental changes. An AAPB strain Erythrobacter sp. JL475 and a non-AAPB strain Erythrobacter sp. JL316 were used as the experimental bacteria, both of which were isolated from the South China Sea. The results showed that light-cultured AAPB showed higher MP and biomass at 10°C, suggesting an obvious stimulation of light on AAPB growth. By contrast, dark-cultivated JL475 had higher MP and biomass at higher temperature (20, 30 and 40°C). The rate of heterotrophic respiration at different temperature environment ranked as follows: dark-cultivated JL316 > dark-cultivated JL475 > light/dark cycling cultivated JL475. Light undoubtedly increased the cell viability of AAPB, especially of apoptosis cells. The CTC⁺% at different carbon concentration ranked as follows: light/dark cycling cultivated JL475 > dark-cultivated JL316 > dark-cultivated JL475. It was concluded that the heterotrophic respiration would played a key role in energy metabolism of AAPB, photosynthesis may provide an advantage for AAPB to survive in a variety of diverse environments.

Key words: Flow cytometry, aerobic anoxygenic phototrophic bacteria, membrane potential, respiration