Treatment of nitrogen and phosphorus in wastewater by heterotrophic N- and P-starved microalgal cell

• Published in: Applied Microbiology and Biotechnology 2023, Vol.107 (4), p.1477
• Main Authors: Gao, Weizheng, Guan, Yueqiang, Li, Yiming, Zhang, Xinwei, Fu, Zhongxiang, Zhang, Zhao
• Format: Report
• Language: English
• Subjects: Analysis; Fatty acids; Measurement; Methods; Nitrogen; Phosphorus; Polymerase chain reaction; Purification; Sewage
• ISSN: 0175-7598
• DOI: 10.1007/s00253-023-12380-z

Nitrogen (N) and phosphorus (P) are two major pollutants present in aquaculture wastewater, and their concentrations often do not meet discharge standards. In the present study, the N and P removal efficiency of nutrient-deficient cells (S group) was significantly higher than that of photoautotrophic cells (P group) and heterotrophic cells (H group). After incubation with wastewater, the N and P content of S group cells was significantly increased and reached a level similar to that of the P group and H group cells after 6 days of treatment. Additionally, in the S group cells, the content of total fatty acids (TFAs), which can be used to supply energy and organic carbon for N and P absorption, significantly decreased. In addition, the protein and nucleic acid contents of the S group cells also significantly increased, which revealed the biosynthetic flow of assimilated N and P. Comparative transcriptome analysis showed that compared with the P group and H group, the N metabolism, ribosome, RNA polymerase, and fatty acid degradation pathways were significantly upregulated in the S group cells, and the fatty acid biosynthesis pathway was significantly downregulated, which was in agreement with the biochemical results. In summary, our study showed that N- and P-starved heterotrophic cells are ideal for use in wastewater N and P removal processes. Keypoints * The N and P removal efficiencies of the S group were higher than P and H groups * Fatty acids were degraded to supply energy and carbon for N and P absorption * N metabolism and fatty acid degradation pathways were upregulated in the S group