Enhancement of photo-driven biomethanation under visible light by nano-engineering of Rhodopseudomonas palustris

Biomethanation is of great interest as it can transform CO₂ to methane under ambient conditions. In particular, genetically engineered bacterium of Rhodopseudomonas palustris showed great promise for one-step biomethanation powered by solar energy, which is attractive for CO₂ fixation as well as solar energy storage. However, biomethanation with R. palustris under visible light is inefficient due to its poor visible light response. In this study, CdS quantum dots with excellent visible light response were prepared and R. palustris/CdS hybrid cells were constructed. Interestingly, this bio-nano-hybrid cells showed high cell viability without significant cell damage, and the biomethanation performance of was enhanced about ~ 79% compared to that of the bare R. palustris cells. Moreover, the effects of different parameters on the methane production of this bio-nano-hybrid cells were determined, and the methane production rate was further improved by parameter optimization. This work demonstrated an efficient approach to reinforce the biomethanation of bacteria under unfavorable light wavelength, which would be helpful to extend the light spectra for photo-driven biomethanation.