Myxococcal predation on cyanobacterial populations: Nutrient effects1

Abstract

Myxococcus fulvus BGO2, a cyanobacteriolytic bacterium, reduced densities of the cyanobacteria Nostoc muscorum and Phormidium luridum in six inorganic media and in filtered water from Lake Erie when inoculated to give initial myxococcal densities of 5 × 106 cells ml−1. When initial myxococcal densities were lower, the reduction in Nostoc density was delayed in a nutrient‐rich medium and did not occur in a nutrient‐poor medium. These laboratory results suggest that the absence of myxobacteria in cyanobacterial blooms and the absence of cyanobacterial population control by related lytic bacteria, found in natural blooms, may be due, in part, to insufficient inorganic nutrient fertility to support growth of lytic bacterial populations to densities necessary to cause significant cell lysis in host populations.