Overexpressing F0/F1 operon of ATPase in Rhodobacter sphaeroides enhanced its photo-fermentative hydrogen production

The effect of atp genes overexpression in Rhodobacter sphaeroides HY01 on the amount of ATP, nitrogenase activity and hydrogen production were studied. The ATP content of ZTHF0 (F0 operon⁺), ZTHF1 (F1 operon⁺) and ZTHFF (F0 operon⁺, F1 operon⁺) was 6.5 ± 0.2 nmol/mL, 7.6 ± 0.2 nmol/mL and 8.3 ± 0.3 nmol/mL, respectively, which enhanced by 20.3%, 40.7%, and 53.7% compared with that of the control strain ZTH (pRK415⁺), respectively. However, the nitrogenase activities of ZTHF0, ZTHF1 and ZTHFF were 35.8 ± 0.5 nmol acetylene/(min·mg-dcw), 40.1 ± 0.7 nmol acetylene/(min·mg-dcw) and 29.3 ± 0.7 nmol acetylene/(min·mg-dcw), respectively, which increased by 18.2%, 32.3% and 0% compared with that of ZTH, respectively. The expression level of atp genes by real-time PCR showed that ZTHF0 or ZTHF1 only enhanced the expression of F0 operon or F1 operon, respectively, and ZTHFF enhanced the expression of both F0 and F1 operons. At the 5000 ± 200 lux with 10 mL culture, the hydrogen yields of ZTHF0 and ZTHF1 were 7636 ± 59 mL/L-culture and 8458 ± 76 mL/L, which increased by 10.5% and 27.8% compared with that of the control strain, respectively. Moreover, the maximum hydrogen evolution rate of ZTHF0 and ZTHF1 were 94.5 ± 4.1 mL/(Lh) and 103.1 ± 5.0 mL/(Lh), which enhanced by 15.4% and 20.6% compared with that of the control strain, respectively. The results suggested that overexpressing F0 operon or F1 operon could improve ATP content and hydrogen production performance in R. sphaeroides.