RESUMEN
Mutagenesis and screening of hydrogen-producing photosynthetic bacteria,Rhodobacter sp.R7 strain,was investigated by using the combination mutation of ultraviolet ray and LiCl and layer plating methods.A carotenoid mutant named R726 strain was obtained.The plate phenotype properties in carotenoid mutant were different from that of parent strains.Living cells spectra showed that absorption peak of 550 nm was appeared in carotenoid mutant,but not in parent strain.The absorption spectra of extraction of pigment further confirmed the difference of carotenoid composition between the mutant and parent strains.The result of TLC on silica gel plate showed that mutant has a lack of yellow carotenoid composition which occurs in parent strain.H_2 productivity and biomass in carotenoid mutant was higher than that of parent strain.These results revealed that mutant has a modified carotenoid biosynthesis pathway.