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A GROWTH ADVANTAGE FOR MICROCYSTIN PRODUCTION BY MICROCYSTIS PCC7806 UNDER HIGH LIGHT 1
Author(s) -
Phelan Richard R.,
Downing Timothy G.
Publication year - 2011
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2011.01056.x
Subject(s) - biology , microcystis , microcystin , strain (injury) , nitrate , botany , growth rate , food science , cyanobacteria , toxicity , zoology , ecology , genetics , chemistry , geometry , mathematics , organic chemistry , bacteria , anatomy
Batch cultures of both Microcystis PCC7806 and a mcyA − knockout mutant (MT) of PCC7806 were cultured at three different light intensities and five media treatments, so as to vary cellular N:C ratios and concentrations and sampled daily over 5 d for analysis of microcystin concentration, cell numbers, and residual nitrate in the growth medium. A competitive survival advantage was noted at a high‐light level (37 μmol photons · m −2 · s −1 ), where the toxic strain survived while the nontoxic strain became chlorotic. A strong correlation ( r 2 = 0.91, P < 0.001, N = 22) between microcystin concentration and growth rate was observed at high‐light conditions. No advantage was observed at optimal or low‐light conditions, and media composition had no significant effect on the relationship between toxicity and survival at high‐light conditions. These data suggest a possible role for microcystin in protection against photooxidation.