Fig.4

Effect of a cell density, b substrate concentration, c L-Cys concentration, and d light intensity on the biomethanation performance of RP/CdS hybrid cells. Apart from the tested parameter, other experimental conditions were the same with those used in Fig. 3. Statistical significance of differences was analyzed by t-test, *p > 0.1, #p < 0.01 (marked condition vs. unmarked condition)