Stress and Recovery Responses of Microcystis aeruginosa Exposed to Extreme Light for Different Durations

Abstract

Cyanobacterial growth is a significant problem in most parts of the world. Control measures are necessary to suppress cyanobacterial growth in natural water bodies. When the control measures were discontinued, cyanobacteria growth rebounded quickly. This study was conducted to provide insight into the stress and recovery responses of cyanobacteria. Microcystis aeruginosa was exposed to extreme light for 8 days, and the changes in response to the light exposure were observed. Post-exposure recovery performances were accessed by allowing Cyanobacteria to recover under optimum conditions for 8 days. Extreme light exposure causes stress on M. aeruginosa, but by adjusting the growth, pigmentation, chlorophyll fluorescence, and antioxidant levels, M. aeruginosa surpasses the stress. M. aeruginosa showed sudden changes in parameters on the eighth day of extreme light exposure. The post-stress recovery capacity of M. aeruginosa was positively correlated with the exposure duration. These findings suggest that exposure to light stress causes hardening of M. aeruginosa. The inter-parameter relationships differed between the stress and recovery phases. Besides, non-photochemical quenching was strongly correlated with cellular H2O2 content, which can indirectly explain the oxidative stress status of M. aeruginosa. This study highlights the research requirement on the post-stress recovery capacity of M. aeruginosa.