The features of extracellular dissolved organic carbon (EDOC) generation in two typical aerobic sulfur-oxidizing bacteria (Thiobacillus thioparus DSM 505 and Halothiobacillus neapolitanus DSM 15147) and its impact on CO₂ fixation during chemoautotrophic cultivation process were investigated. The results showed that EDOC accumulated in both strains during CO₂ fixation process. Large molecular weight (MW) EDOC derived from cell lysis and decay was dominant during the entire process in DSM 505, whereas small MW EDOC accounted for a large proportion during initial and middle stages of DSM 15147 as its cytoskeleton synthesis rate did not keep up with CO₂ assimilation rate. The self-generated EDOC feedback repressed cbb gene transcription and thus decreased total bacterial cell number and CO₂ fixation yield in both strains, but DSM 505 was more sensitive to this inhibition effect. Moreover, the membrane bioreactor effectively decreased the EDOC/TOC ratio and improved carbon fixation yield of DSM 505. Copyright © 2017 Elsevier B.V.
CitationWang, Y.-N., Tsang, Y. F., Wang, L., Fu, X., Hu, J., Li, H, & Le, Y. (2018). Inhibitory effect of self-generated extracellular dissolved organic carbon on carbon dioxide fixation in sulfur-oxidizing bacteria during a chemoautotrophic cultivation process and its elimination. Bioresource Technology, 252, 44-51. doi: 10.1016/j.biortech.2017.12.089
- Sulfur-oxidizing bacteria (SOB)
- CO₂ fixation
- Extracellular dissolved organic carbon (EDOC)
- cbb gene transcription
- Membrane bioreactor (MBR)