Contrasting microcystin production and cyanobacterial population dynamics in two Planktothrix dominated freshwater lakesToxic and nontoxic Microcystis colonies in natural populations can be differentiated on the basis of rRNA gene internal transcribed spacer diversityMicrocystis genotype succession in relation to microcystin concentrations in freshwater lakesBiphasic kinetics of a methanotrophic community is a combination of growth and increased activity per cellHigh-resolution differentiation of cyanobacteria by using rRNA-Internal Transcribed Spacer denaturing gradient gel electrophoresis