There were three continuous batch cultures,and by culturing in three photoperiod(i.e.,light∶dark ratio,respectively for 24h∶0h,12h∶12hand 8h∶16h),the effect of photoperiod on growth and activity of photosystem was studied in order to support artificial culture of Nostoc sphaeroides Kutzing indoor.The research results indicated that there was obvious growth inhibition of 24 hours continuous illumination on the second and third batch cultures,which indicate that 24 hours continuous illumination is not good fo...