Inhibition of cyanobacterial photosynthetic activity by natural ketones

Abstract

Microbial volatiles have a significant impact on the physiological functions of prokaryotic and eukaryotic organisms. Various ketones are present in volatile mixtures produced by plants, bacteria, and fungi. Our earlier results demonstrated the inhibitory effects of soil bacteria volatiles, including ketones, on cyanobacteria. In this work, we thoroughly examined the natural ketones, 2‐nonanone and 2‐undecanone to determine their influence on the photosynthetic activity in Synechococcus sp. PCC 7942. We observed for the first time that the ketones strongly inhibit electron transport through PSII in cyanobacteria cells in vivo. The addition of ketones decreases the quantum yield of primary PSII photoreactions and changes the PSII chlorophyll fluorescence induction curves. There are clear indications that the ketones inhibit electron transfer from QA to QB, electron transport at the donor side of PSII. The ketones can also modify the process of energy transfer from the antenna complex to the PSII reaction center and, by this means, increase both chlorophyll fluorescence quantum yield and the chlorophyll excited state lifetime. At the highest tested concentration (5 mM) 2‐nonanone also induced chlorophyll release from Synechococcus cells that strongly indicates the possible role of the ketones as detergents.

Four New Genes of Cyanobacterium Synechococcus elongatus PCC 7942 Are Responsible for Sensitivity to 2-Nonanone

“…PCC 9305), Drosophila melanogaster and nematodes [7]. In our experiments [16], the effects of two ketones (2-nonanone and 2-undecanone) on the cyanobacterial photosynthetic apparatus were very similar causing significant disturbances in the photosynthetic apparatus of cyanobacterium Synechococcus elongatus PCC 7942 by inhibition of electron transport through photosystem II. Ketones can participate in antagonistic interactions in the environment raising the question about the cellular targets, on which ketones act and about the mechanisms of their action.…”

Influence of the antiseptic octenidine on spectral characteristics and energy migration processes in photosystem II core complexes

“…In this regard, it may become relevant to monitor the state of PSII in aquatic organisms for environmental contamination with antiseptics. One of the methods for such monitoring, for example, is remote analysis of fluorescence induction, which reflects the lifetime state of PSII in aqueous photosynthetic organisms (Voronova et al 2019 ).…”