Abstract
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.
Highlights
CO2 methanation which refers to transformation of CO2 to methane attracted much attention, as it can fix the greenhouse gas of CO2 and produce the renewable energy of methane (Zheng et al 2018; Ma et al 2020a, b)
The Rhodopseudomonas palustris CGMCC 1.2180 (RP)/CdS bio-nano-hybrid cells were constructed by incubating the RP cells with CdS quantum dots (QDs)
In summary, this work demonstrated the construction of bio-nano-hybrid bacterial cells for biomethane production from CO2 under visible light irradiation
Summary
CO2 methanation which refers to transformation of CO2 to methane attracted much attention, as it can fix the greenhouse gas of CO2 and produce the renewable energy of methane (Zheng et al 2018; Ma et al 2020a, b). (Nikiforov et al 2020; Wang et al 2017a, b; Ferry 2011) Among these methods, biomethanation which uses the microorganism as the catalytic module holds great promise because it required minimum energy and operation investment. A new pathway for methane production by bacterial Fe-only nitrogenase was explored (Fixen et al 2016; Zheng et al 2018). 9% of diverse nitrogen-fixing microorganisms contained this Fe-only nitrogenase, suggesting this new biomethanation pathway is widespread among the microorganisms (Zheng et al 2018; Fixen et al 2018). This pioneering finding implied the possibility to use nitrogen-fixing bacteria for biomethanation.
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