Performance and mechanism of carbon dioxide fixation by a newly isolated chemoautotrophic strain Paracoccus denitrificans PJ-1.

CO is regarded as a major contributor to the global warming. CO utilization is promising to reduce the CO emissions. Currently, the biofixation of CO using chemoautotrophs has markedly gain interest in CO utilization. In this study, a newly isolated chemoautotroph, Paracoccus denitrificans PJ-1, was used for the biofixation of CO under anaerobic condition. Experimental results revealed that Paracoccus denitrificans PJ-1 achieved a high carbon fixation rate (13.25 mg·L·h) which was ∼10 times faster than the previous reported chemotrophic bacteria using thiosulfate as electron donor. The best CO fixation activity of Paracoccus denitrificans PJ-1 was achieved at the pH value of 9.0 and CO concentration of 20 vol%. Meanwhile, a high CO fixation yield of 106.03 mg·L was reached. The presence of oxygen was adverse to the biofixation, indicating that strain PJ-1 was more suitable for CO fixation in anaerobic environments. Carbon mass balance analysis revealed that the carbon from CO was mainly fixed into the extracellular organic carbon rather than the biomass. GC-MS analysis and cbbL gene test revealed that Paracoccus denitrificans PJ-1 fixed CO through the Calvin-Benson-Bassham cycle and mainly converted CO to oxalic acid and succinic acid. Overall, the excellent CO fixation capacity of Paracoccus denitrificans PJ-1 suggests that it had potential for CO utilization.

Copyright © 2020 Elsevier Ltd. All rights reserved.