Effects of Bacterial Density and the Abundance of Limiting Resources for Bacteria on the Removal Process of Bacteria by Predation.

Abstract

This paper investigated effects of the abundance of total bacterial populations and of limiting resources for bacteria on the removal process of bacteria by predation in a microbial community. For this analysis, an experimental, continuous flow system of a column bed-reactor was employed, to which bacterial suspension containing three species was supplied. The column reactor contains fiber carrier seeded with activated sludge. Population dynamics of bacteria, protozoa, and metazoa in influent and in effluent were examined under several conditions with varying total bacterial density and concentration of limiting resources contained in influent. The experimental results showed the tendency that bacterial density in the effluent was not affected either by the influent total bacterial density or by the resource abundance, which is explained using a mathematical model of one resource, one prey and one predator species. Experimental results suggests that the higher influent abundance of bacteria and/or resources for bacteria raise the size of predacious populations sustained in the community and species richness as well, which keeps the bacterial density in the effluent constant.