The Influence of Microcystin-LR and Microcystin-LR-Producing Trichormus variabilis (Cyanobacteria) on Green Microalgae in Laboratory Conditions

Abstract

The most studied cyanobacterial toxins are microcystins (MCs), of which microcystin-LR (MC-LR) is the most common, with the most experimentally documented toxicity to aquatic species. The aim of the present study is to examine the influence of an ecologically relevant MC-LR concentration (10 µg L-1) on green microalgae (Chlorella sp., Scenedesmus sp., Coelastrum sp.) by determining the concentration of chlorophyll a. In addition, the influence of the Trichormus variabilis was monitored, characterized as MC-LR producer, on the growth of green microalgae, using the co-cultivation method. MC-LR was detected, quantified, and identified in the methanolic extract of T. variabilis using the high-performance liquid chromatography (HPLC). The study revealed that MC-LR significantly impacted green microalgae growth causing stimulation. In contrast, T. variabilis in co-culture exhibited only an inhibitory effect on the growth. The study revealed the allelopathic effect of environmentally relevant microcystin-LR concentration on green microalgae.