Primary photosynthetic processes of Thalassiosira weissflogii under the effect of ciprofloxacin

Fluoroquinolone antibiotics such as ciprofloxacin have been actively used in medical practice, including the COVID-19 pandemic, to suppress adverse bacterial infections. Widespread application and improper disposal have resulted in the ubiquity of antibiotics in the environment, which can affect aquatic life, including phytoplankton. The effect of fluoroquinolone antibiotics on the photosynthetic processes of marine diatoms, which are the main producers in marine ecosystems, has been little studied. In this work the effect of the antibiotic ciprofloxacin on the primary photosynthetic processes in the marine diatom Thalassiosira weissflogii was studied. It has been shown that ciprofloxacin affects the functioning of PSII, preventing the transfer of absorbed energy from the excited antenna chlorophyll molecules to the PSII RC (φDo). Under the influence of ciprofloxacin, a decrease in the efficiency of electron donation to P680+ (FV / FO), inhibition of the quantum yield of PSII (FV / FM), a decrease in the proportion of active RCs (ABS / RC), and an increase in the dissipation of absorbed energy in RCs (DIo / RC) were revealed. It has been shown that the mechanism of action of ciprofloxacin is associated with damage of PSII RC. Ciprofloxacin enhances the photosensitivity of microalgae and causes an increase in lipid peroxidation products. It is proposed to apply the parameters of chlorophyll fluorescence analyzing the effect of antibiotics on microalgae.