Influence of UV-B radiation on the fitness and toxin expression of the cyanobacterium Cylindrospermopsis raciborskii

BEAMUD SG; PAULA VICO; SIGNE HAAKONSSON; GABRIELA MARTINEZ DE LA ESCALERA; CLAUDIA PICCINI; BEATRIZ BRENA; MACARENA PIREZ; SYLVIA BONILLA

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2015

0018-8158

The harmful bloom-forming cyanobacterium Cylindrospermopsis raciborskii grows in freshwaters over a widerange of light conditions. This species has increased its global distributionrecently. The influence of ultraviolet radiation (UVR) on the fitness and toxinproduction of C. raciborskii has notpreviously been explored. We performed short-term experiments with three C. raciborskii strains (MVCC19, LB2897and CYP011K), and we compared their responses with other bloom-forming species(Microcystis sp.1 and Plankthotrix agardhii) to determine theimpact of UV-B radiation on pigments, biomass and morphological traits. Inaddition, we analyzed the effect of UV-B on the saxitoxin content and sxtU gene expression in the strain MVCC19.C. raciborskii strains were stresseddifferentially by UV-B exposure as evidenced by changes in growth, morphologyand heterocytes number. A significant increase in saxitoxin concentration and sxtU gene expression under UV-B, suggeststhat toxin production in C. raciborskiican be a response to UV-B stress. In comparison, Microcystis sp.1 was more tolerant while P. agardhii was severely impacted by UV-B, indicating alsodifferent sensitivities among cyanobacteria to UVR. Our results underscore theinfluence of UVR on C. raciborskii andthe differences between strains whichshowed phenotypic plasticity, which potentially could affect its distributionin freshwaters.