Chlortetracycline (CTC) usually presents in livestock wastewater with oxytetracycline (OTC), causing damage to human health and ecosystems. It's urgent to seek low-cost and ecofriendly technology for antibiotics removal. In this study, effects of CTC and CTC + OTC (CTC:OTC= 1:1, g/g) on Spirulina platensis have been investigated. EC50 value of CTC for S. platensis was 8.76 mg/L at 96 h and risk quotient value in wastewater was 15.85. Inhibition of CTC on S. platensis gradually enhanced with increase of CTC, but CTC + OTC below 1.0 mg/L didn't harm the growth of microalgae. Chlorophyll-a (Chl-a) and carotenoid content showed a parabolic trend with extension of time at CTC group. Chl-a synthesis gradually decreased with increase of CTC + OTC stress. High concentrations of CTC and CTC + OTC showed obvious inhibition on phycocyanin production. Polyunsaturated fatty acids (PUFA) and saturated fatty acids (SFA) contents peaked at 1.0 mg/L CTC, corresponding to the minimum of superoxide dismutase (SOD) activity in S. platensis. SFA and PUFA contents decreased when CTC + OTC content was above 2.0 mg/L. CTC and CTC + OTC (both over 2.0 mg/L) stimulated production of dissolved extracellular organic matters in S. platensis. Removal efficiency of CTC by S. platensis was about 98.63–99.95% and its biodegradation pathways were hydroxylation and side-chain breakdown.
Bibliographical noteFunding Information:
This work was supported by Research Project of State Key Laboratory of Food Science and Technology, Nanchang University ( SKLF-ZZB-201915 ); The Key Project of Jiangxi Provincial Department of Science and Technology ( 20181BAB206030 , 20181BBF60026 , GCXZ2014-124 , 20161BBF60057 ); National Natural Science Foundation of China (No. 21878139 , 21878237 , 21706087 , 21466022 , 21766019 , 51708308 ) and the Post-doctoral Innovative Talents Support Program of China ( BX20190147 ).
© 2021 Elsevier B.V.
- Biodegradation pathway
- Dissolved extracellular organic matters
- Intracellular metabolites
- S. platensis