Growth, toxin production, active oxygen species and catalase activity of Microcystis aeruginosa (Cyanophyceae) exposed to temperature stress

LEDA GIANNUZZI; BERND KROCK ; MELINA CELESTE CRETTAZ MINAGLIA⁎; LORENA ROSSO ; CHRISTIAN HOUGHTON ; DANIELA SEDAN ; GABRIELA MALANGA ; MARIELA ESPINOSA; DARÍO ANDRINOLO ; MARCELO HERNANDO ⁎

COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. C, COMPARATIVE PHARMACOLOGY AND TOXICOLOGY.

ELSEVIER SCIENCE BV

Año: 2016 vol. 189 p. 22 - 30

0742-8413

Microcystis are known for their potential ability to synthesize toxins,mainlymicrocystins (MCs). In order to evaluatethe effects of temperature on chlorophyll a (Chl a), growth, physiological responses and toxin production ofa nativeMicrocystis aeruginosa, we exposed the cells to low(23 °C) and high (29 °C) temperature in addition to a26 °C control treatment. Exponential growth ratewas significantly higher at 29 °C compared to 23 °C and control,reaching 0.43, 0.32 and 0.33 day−1 respectively. In addition, therewas a delay of the start of exponential growthat 23 °C. However, the intracellular concentration of Chl a decreased significantly due to temperature change. Asignificant increase in intracellular ROS was observed in coincidencewith the activation of enzymatic antioxidantcatalase (CAT) during the first two days of exposure to 23° and 29 °C in comparison to the control experiment,decreasing thereafter to nearly initial values. Five MCs were determined by LC-MS/MS analysis. In the experiments,the highest MC concentration, 205 fg [Leu1] MC-LR.cell−1 expressed as MC-LR equivalent was measuredin the beginning of the experiment and subsequently declined to 160 fg.cell−1 on day 2 and 70 fg.cell−1 on day 4in cells exposed to 29 °C. The same trend was observed for all other MCs except for the least abundant MC-LRwhich showed a continuous increase during exposure time. Our results suggest a high ability of M. aeruginosato perceive ROS and to rapidly initiate antioxidant defenses with a differential response on MC production.