Regulatory mechanism of high-concentration CO on polysaccharide accumulation in Tetradesmus obliquus cultured in sludge extract.

Microalgae such as Tetradesmus obliquus have great potential in immobilizing high-concentration CO and removing highly toxic organic matters, which could be produced from coal chemical industry and coal chemical wastewater biological treatment process. In this study, Tetradesmus obliquus was cultured in sludge extract and high-concentration CO was added. The maximum cell density and dry weight were respectively (111.46 ± 4.87) × 10 cell/mL and 3.365 ± 0.168 g/L under 30% CO. Tetradesmus obliquus accumulated the most polysaccharides (629.60 ± 31.48 mg/L) on the 30th day under 30% CO. The results of proteomic showed that the upregulation of A0A2Z4THB7 and A0A383VAT1 promoted polysaccharide accumulation. Polysaccharide was mainly formed at the stable phase instead of the log-growth phase due to the abiotic stress caused by high TOC at the log-growth phase. Collectively, this study revealed the regulatory mechanism of high-concentration CO on the toxicity removal and accumulation of polysaccharides in Tetradesmus obliquus.