Figure 3
Co-expression effect of proteorhodopsin and hydrogenase on H2 production. (A) Co-expression effect of proteorhodopsin with exogenous retinal and hydrogenase on H2 production. Recombinant E. coli BL21(DE3) with a single plasmid, pET-HmH/pR, were grown with or without retinal under a light intensity of 70 μmole photon/(m2·s). E. coli harboring the parent pET-21b vector was used as a negative control. (B) Co-expression effect of proteorhodopsin with endogenous retinal and hydrogenase on H 2 production. Recombinant E. coli BL21(DE3) with two plasmids, pET-HmH and pACYC-RDS, were grown under the same light conditions. H2 production was measured using GC as described in the Methods. Each value and its error bars represent the mean of two independent cultures and the standard deviation, respectively.