Light–dark duration alternation effects on Rhodobacter sphaeroides growth, membrane properties and bio-hydrogen production in batch culture

摘要: Abstract The effects of light–dark duration alternation on bacterial growth and hydrogen (H 2 ) production performance Rhodobacter sphaeroides MDC 6522 from Armenian mineral springs were firstly investigated in batch culture. Five types applied: 1st culture was illuminated continuously (control); 2nd 3rd cultures after inoculation during 24–48 h, then dark conditions applied; 4th 5th 24–48 h period. R. did not grow well the conditions, but H restored upon illumination. When 24 h period, yield maintained at a constant high level 96–144 h, photo-fermentation delayed up to 144 h, compared control. till started (48 h), applied, ability persisted 120 h, whereas control cells observed. Moreover, results indicated that affected formation photosynthetic pigments membrane + conductance. This study is significant for understanding metabolism regulation mechanisms application purple bacteria biotechnology.