Disrupting mopAB and mdtB genes affects hydrogen production performance of Rhodobacter capsulatus

Abstract

In Rhodobacter capsulatus, hydrogen production is predominantly limited by nitrogenase activity and light conversion efficiency. Modifying related genes can potentially mitigate these limitations. In this study, partial deletions of the mopAB and mdtB genes were performed in the R. capsulatus JL1 (WT) genome. Resultant mutants, JL11 (mopAB-) and JL15 (mopAB-, mdtB-), demonstrated favorable growth on MedA in photosynthetic anaerobic conditions. However, the growth of JL12 (mdtB-) was inhibited. Batch fermentation experiments revealed an augmented hydrogen production in JL15, achieving a remarkable 177.89 ± 9.98 mmol L−1. Furthermore, the light conversion efficiencies of JL15 reached 4.6% and 3.3% under 3 ± 0.5 klux and 7 ± 0.5 klux, respectively. In comparison, JL1 (WT) achieved efficiencies of 3.3% and 1.8% with nitrogenase activities of 6.16 ± 0.11 and 6.90 ± 0.30 nmol min−1·mg−1. These findings highlight the promising potential of co-deletion as a strategy for enhancing hydrogen production.