Two-stage continuous cultivation of microalgae overexpressing cytochrome P450 improves nitrogen and antibiotics removal from livestock and poultry wastewater

Rui Xiao; Chang Tian; Haijun Wang; Hui Zhang; Huan Chen; Howard H Chou

doi:10.1016/j.biortech.2024.131994

Two-stage continuous cultivation of microalgae overexpressing cytochrome P450 improves nitrogen and antibiotics removal from livestock and poultry wastewater

Bioresour Technol. 2024 Dec 16:418:131994. doi: 10.1016/j.biortech.2024.131994. Online ahead of print.

Authors

Rui Xiao¹, Chang Tian², Haijun Wang³, Hui Zhang³, Huan Chen⁴, Howard H Chou⁵

Affiliations

¹ CAS Key Laboratory of Quantitative Engineering Biology, Center for Synthetic Biochemistry, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, China; Department of Environmental Engineering and Earth Science, Clemson University, South Carolina 29634, United States.
² CAS Key Laboratory of Quantitative Engineering Biology, Center for Synthetic Biochemistry, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, China.
³ College of Resources and Environment, Chengdu University of Information Technology, Chengdu 610225, China.
⁴ Department of Environmental Engineering and Earth Science, Clemson University, South Carolina 29634, United States.
⁵ CAS Key Laboratory of Quantitative Engineering Biology, Center for Synthetic Biochemistry, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, China. Electronic address: howard@siat.ac.cn.

PMID: 39694106
DOI: 10.1016/j.biortech.2024.131994

Abstract

Improper treatment of livestock and poultry wastewater (LPWW) rich in ammonium nitrogen (NH₄-N) and antibiotics leads to eutrophication, and contributes to the risk of creating drug-resistant pathogens. The design-build-test-learn strategy was used to engineer a continuous process using Chlorella vulgaris to remove NH₄-N and antibiotics. The optimized system removed NH₄-N at a rate of 306 mg/L/d, degraded 99 % of lincomycin, and reduced the hydraulic retention time to 4 days. The physiological, metabolic, and genetic mechanisms used by microalgae to tolerate LPWW, remove NH₄-N, and degrade antibiotics were elucidated. A new cytochrome P450 enzyme important for NH₄-N and antibiotic removal was identified. Finally, application of synthetic biology improved the NH₄-N removal rate to 470 mg/L/d, which is the highest removal rate using microalgae reported to date. This research contributes to the mechanistic understanding of wastewater detoxification by microalgae, and the goal of achieving a circular bioeconomy for nutrient and water recycling.

Keywords: Ammonium removal; Chlorella vulgaris; Continuous stirred tank reactor; Nutrient recycling; Xenobiotic degradation.