Authors: Feng Xu Wei Zhu Man Xiao Ming Li
Publish Date: 2015/09/09
Volume: 28, Issue: 3, Pages: 1533-1541
Abstract
Single cells of five different Microcystis species M ichthyoblabe M viridis M flosaquae M wesenbergii and M aeruginosa were batchcultured at different temperatures and light intensities a 25 °C and 50 μmol photons m−2 s−1 control culture b 25 °C and 10 μmol photons m−2 s−1 and c 15 °C and 50 μmol photons m−2 s−1 The extracellular polysaccharide content was significantly higher in treatments b and c than in the control treatment All Microcystis species existed as single cells under the control treatment but formed colonies in treatments b and c All of the colonies were irregular with indistinct margins M ichthyoblabe M viridis M flosaquae and M wesenbergii formed colonies with similar morphologies and their cells were loosely aggregated In contrast M aeruginosa formed denser colonies with no distinct holes The colony morphologies differed from the classic morphology of M ichthyoblabe fieldgrown colonies but resembled that of small colonies found in Lake Taihu Yangtze Delta Plain China during early spring This indicates that field and laboratorygrown colonies are governed by similar formation processes We suggest that in laboratory and field environments M ichthyoblabe or M flosaquae colonies are representative of small colonies formed from single Microcystis cells whereas the morphology of older colonies evolves to resemble M wesenbergii and M aeruginosa colonies
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