| Abstrakt: |
The use of photosynthetic bacteria (PSB) in wastewater bioconversion is a novel method that can simultaneously realize wastewater treatment and resource recovery. The metabolism of PSB is significantly influenced by dissolved oxygen (DO) conditions; however, the rates of respiration and photosynthesis in PSB metabolism remain unclear. In this study, chemical oxygen demand (COD) removal and PSB biomass were tested, then the respiration and photosynthesis rates were deeply analyzed, and related key enzymes and genes were also discussed. The results showed that COD removal increased with the increase in oxygen concentration, and reached 93% at DO > 2 mg/L. The high DO level also enhanced the growth of PSB. The maximum PSB respiration rates under DO < 0.5, 0.5–2, and >2 mg/L were 216, 237, and 226 O2mg/g h, respectively and the maximum photosynthesis rates were 19, 15, and 15 biomass mg/g h, respectively. Changes in respiration enzyme activity corresponded to those in the respiration rate, and phosphofructokinase and pyruvate kinase activity were higher under high DO concentrations. The respiration gene expression also corresponded to the respiration rate. The photosynthesis enzyme activity corresponded to the photosynthesis rate, and ribulose-1,5-bisphosphate carboxylase/oxygenase activity was the highest under DO < 0.5 mg/L. This study provides important basic data of PSB, which made contributions to large-scale practical application of PSB wastewater bioconversion. It also provides a unique biological sample for respiration and photosynthesis processes of biological research. |
