From winter dormancy to spring bloom: Regulatory mechanisms in Microcystis aeruginosa post-overwintering recovery

Chenjun Fu; Xinyi Wang; Jing Yu; Hu Cui; Shengnan Hou; Hui Zhu

doi:10.1016/j.watres.2024.122807

From winter dormancy to spring bloom: Regulatory mechanisms in Microcystis aeruginosa post-overwintering recovery

Water Res. 2024 Nov 17:269:122807. doi: 10.1016/j.watres.2024.122807. Online ahead of print.

Authors

Chenjun Fu¹, Xinyi Wang², Jing Yu², Hu Cui², Shengnan Hou², Hui Zhu³

Affiliations

¹ State Key Laboratory of Black Soils Conservation and Utilization, Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² State Key Laboratory of Black Soils Conservation and Utilization, Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
³ State Key Laboratory of Black Soils Conservation and Utilization, Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China; University of Chinese Academy of Sciences, Beijing 100049, China; Jilin Provincial Engineering Center of CWs Design in Cold Region & Beautiful Country Construction, Changchun 130102, China. Electronic address: zhuhui@iga.ac.cn.

PMID: 39577387
DOI: 10.1016/j.watres.2024.122807

Abstract

Cyanobacterial blooms pose a significant environmental threat in freshwater ecosystems. These cyanobacteria exhibit resilience to cold and dark conditions during winter and flourish as temperature rise in warmer seasons. However, there is a limited understanding of the dynamic growth recovery process and regulatory signaling mechanisms in cyanobacteria after overwintering. In this study, we employed Microcystis aeruginosa (M. aeruginosa) as a model to simulate its growth recovery when subjected to increasing temperature after overwintering under low temperature (4 °C) and dark conditions. We investigated changes in cell growth, microcystin levels, and signaling pathways throughout this recovery phase. Our results indicated that compared to the non-overwintering treatment (T1), the overwintered treatment (T2) experienced a 55.6 % decrease in algae density and a significant reduction in microcystin-LR (MC-LR) levels within the 15-20 °C temperature range (p < 0.05). Overwintering suppressed photosynthetic efficiency during the recovery phase of M. aeruginosa, activated the antioxidant system, and impaired cellular ultrastructure, making algal cells more vulnerable to death. At the transcriptional level, overwintering down-regulated pathways such as photosynthesis, ribosome, the Calvin cycle, and oxidative phosphorylation, hindering the growth and metabolic capacity of M. aeruginosa. In conclusion, this study highlights the inhibitory impacts of overwintering on growth and metabolism of cyanobacteria during the recovery process. It provides insights into the mechanistic foundations of seasonal cyanobacterial blooms and the crucial role of signaling regulation in these processes.

Keywords: Microcystin-LR; Microcystis aeruginosa; Overwintering; Photosynthesis; Transcriptome.