Environmental Science and Ecotechnology (Nov 2024)

Optimizing UVA and UVC synergy for effective control of harmful cyanobacterial blooms

  • Yinjie Zhu,
  • Jian Ding,
  • Xiaoxiong Wang,
  • Xuejian Wang,
  • Huansheng Cao,
  • Fei Teng,
  • Shishi Yao,
  • Zhiru Lin,
  • Yuelu Jiang,
  • Yi Tao

Journal volume & issue
Vol. 22
p. 100455

Abstract

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Harmful cyanobacterial blooms (HCBs) pose a global ecological threat. Ultraviolet C (UVC) irradiation at 254 nm is a promising method for controlling cyanobacterial proliferation, but the growth suppression is temporary. Resuscitation remains a challenge with UVC application, necessitating alternative strategies for lethal effects. Here, we show synergistic inhibition of Microcystis aeruginosa using ultraviolet A (UVA) pre-irradiation before UVC. We find that low-dosage UVA pre-irradiation (1.5 J cm−2) combined with UVC (0.085 J cm−2) reduces 85% more cell densities compared to UVC alone (0.085 J cm−2) and triggers mazEF-mediated regulated cell death (RCD), which led to cell lysis, while high-dosage UVA pre-irradiations (7.5 and 14.7 J cm−2) increase cell densities by 75–155%. Our oxygen evolution tests and transcriptomic analysis indicate that UVA pre-irradiation damages photosystem I (PSI) and, when combined with UVC-induced PSII damage, synergistically inhibits photosynthesis. However, higher UVA dosages activate the SOS response, facilitating the repair of UVC-induced DNA damage. This study highlights the impact of UVA pre-irradiation on UVC suppression of cyanobacteria and proposes a practical strategy for improved HCBs control.

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