Microcystin production of Microcystis viridis (cyanobacteria) under different culture conditions

Abstract

Toxic cyanobacterium Microcystis viridis was isolated from the eutrophic Dianchi Lake of south-western China. Three microcystins were detected from this strain by high-pressure liquid chromatography. Among them, [Dha 7 ] microcystin-RR is the major component and represents about 70-80% of the total toxins of this strain. We examined its microcystin production pattern in relation to culture conditions such as light intensity, nutrition, temperature, pH and growth phase. Of all the factors examined, light intensity and pH influenced the toxin production much more than other factors. At 25ЊC, a high production of [Dha 7 ] microcystin-RR was obtained at light intensity 15 E s Ϫ1 m Ϫ2 , and both low and high pH (pH 7.0 and pH 9.2) enhanced the yield of microcystin-RR. No strong relationships were found between total toxin and temperature ranging from 15ЊC. The highest production of total toxins was measured in the mid-exponential growth phase and lowest production towards the declining growth phase. Remarkable changes in toxin production and morphology emerged coincidentally following the transfer of nitrogen-deficient cells into fresh MA medium during the time course. These findings may shed light on the correlation between toxin production and morphogenesis of this strain.

Late-summer phytoplankton in western Lake Erie (Laurentian Great Lakes): bloom distributions, toxicity, and environmental influences

“…Given that secondary metabolites are produced by diverse cyanobacteria encompassing varied ecological niches, it is plausible that microcystin synthesis is associated with and/or regulated by environmental factors affecting cell metabolism, growth, and ultimately, abundance . Reports that state microcystin production and/ or cell quota are influenced by select abiotic parameters, including temperature, irradiance, macro/micronutrients, and pH (van der Westhuizen and Eloff 1985;Lukac and Aegerter 1993;Song et al 1998;Downing et al 2005), support this premise.…”

Variation of Microcystis and microcystins coupling nitrogen and phosphorus nutrients in Lake Erhai, a drinking-water source in Southwest Plateau, China

“…Numerous studies based on field samples and laboratory cultures have addressed the question how changes in environmental conditions have an impact on MC production (Neilan et al 2012), including nutrient elements (Song et al 1998;Jiang et al 2008;Wu et al 2006), temperature (Sivonen 1996), pH (Song et al 1998) and light intensity (Sivonen 1990). Nitrogen, phosphorous and the ratio of nitrogen and phosphorus were regarded as the important factors for Microcystis blooms and MC production (Chorus et al 2001;Gupta et al 2001;Gobler et al 2007;Jiang et al 2008;Joo et al 2009).…”

Sorption, degradation and mobility of microcystins in Chinese agriculture soils: risk assessment for groundwater protection

“…More specifically, MC-RR, LR, and Dha 7 LR are commonly found in freshwater cyanobacterial blooms in China. In recent few years, cyanobacterial blooms occurred in many large freshwater lakes such as Lake Dianchi (the 6th largest freshwater lake in China) and Lake Taihu (the 3rd largest freshwater lake in China) with increasing frequency and intensity (Li et al, 2001;Song et al, 1998). As a result, toxic cyanobacterial blooms and MCs have received more attention following the report by Jochimsen and his colleagues (Jochimsen et al, 1998) regarding the deaths of 50 patients exposed to MCcontaminated water during a dialysis treatment.…”