Small water clusters stimulate microcystin biosynthesis in cyanobacterial Microcystis aeruginosa

Abstract

Recent research has indicated that different scales of water clusters can cause different biological effects from normal water clusters. In this study, we used the cyanobacterium Microcystis aeruginosa FACHB-905 as a model organism to investigate the effect of small water clusters (SWCs) on the growth and toxin production of toxic cyanobacteria. The results showed that SWCs were able to stimulate the growth of M. aeruginosa, which resulted in increased cell numbers and higher specific growth rates after a 20-day treatment. Moreover, the SWCs treatment up-regulated microcystin (MC) synthesis and exudation in 6 days in M. aeruginosa. Subsequently, the intracellular MC content decreased after the 16th day. SWCs had positive effects on the photochemical system as well as the uptake of nitrogen and phosphorus for the majority of the period. Moreover, the cell photosynthetic pigment concentrations were transitorily stimulated by SWCs. It is assumed that SWCs stimulated cell growth by promoting photosynthesis as well as nitrogen and phosphorus uptake, whereas the enhanced MC production is related to pigment concentrations (Chl a and carotenoid). This study reveals that SWCs is a novel environmental factor that stimulates growth and enhances MC production in M. aeruginosa.