Dan Wang1, Ning Zhang1, Kaixin Tang1, Yueqiu Bai1, Yanqiu Tian1, Jinlu Hu1
1School of Life Sciences, Northwestern Polytechnical University, Xi’an, Shaanxi 710072, China
Correspondence: Jinlu Hu, hujinlu@nwpu.edu.cn
The persistent organic pollutant perfluorooctanoic acid (PFOA) is ubiquitous in the aquatic environment. However, little is known about its toxicity to cyanobacteria or the mechanisms by which they self-adapt to it. This study revealed that the bloom-forming cyanobacterium Microcystis aeruginosa was initially inhibited and subsequently self-adapted to PFOA exposure for 12 d. PFOA inhibited M. aeruginosa growth but the inhibition rate gradually decreased and stabilized over time. With increasing PFOA concentration, the reactive oxygen species levels and superoxide dismutase and photosystem II activity significantly increased while the respiratory rate, NDH-1 activity, and total carbohydrate content significantly decreased. Self-adaptation mechanisms included the antioxidant pathways, energy transfer and distribution of photosystems, and repair of the PSI and NDH complexes. The patterns of change in the foregoing parameters were consistent with those of the expression levels of the genes in their associated metabolic pathways. In addition, PSII overcompensation might be a strategy by which M. aeruginosa contends with oxidative stress induced by PFOA. Various downstream photosynthesis-related proteins were upregulated in response to increasing PFOA exposure time. These findings may help elucidate the physiological and genetic stress and self-adaptation responses of microalgae to PFOA exposure.