Monoxenic and mixed cultures of the small metazoa Philodina erythrophthalma and Aeolosoma hemprichi isolated from a waste-water treatment process

Abstract

Philodina erythrophthalma (an euryphagous Rotatoria) and Aeolosoma hemprichi (a stenophagous Oligochaeta), isolated from a waste-water treatment process, were grown in monoxemic and mixed cultures using a variety of bacterial species as prey. In monoxenic cultures, P. erythrophthalma could grow by feeding on a wide range of bacterial species, while A. hemprichi exhibited a relatively high prey specificity. The growth rates of P. erythrophthalma and A. hemprichi increased in the mixed culture, compared with those in the respective monoxenic cultures. Interestingly, the sizes of bacterial flocs were observed to increase in the presence of P. erythrophthalma. On the basis of the experimental results, the role of metazoa in a waste-water purification process is discussed.