The improvement of productivity of a photosynthetic purple bacteria, Rhodobacter sphaeroides by manipulating the photosynthetic apparatus

초록

The objective of this study was to investigate the effect of high content of light-absorbing pigments on overall photosynthetic efficiency in high density microalgal cultures. The light harvesting complex Ⅱ (LHC Ⅱ) regulating gene of Rhodobacter sphaeroides, photosynthetic purple bacterium, was removed to construct a mutant strain that had less pigment content. The mutant and wild type strains were cultured under various light intensity by adjusting the distance from the light source. The productivity of the mutant strain was higher at high light intensity (over 118 μE/m2/s) compared with one of the wild type , and was lower at low light intensity (34 μE/m2/s). Especially, the concentration of LHC Ⅱ- mutant strain was 56% higher at 118 μE/m2/s. The reduction of per cell pigment contents in the mutant strain lessened the degree of the mutual shading and thus enhanced the overall photosynthetic efficiency.