Nitrogen Flow in a Chemostat Culture of the Rotifer Brachionus plicatilis

Abstract

Nitrogen flow in a chemostat culture of the rotifer Brachionus plicatilis was measured. It was found that a chemostat could keep the rotifer in a stable condition and were suitable for studying the effect of algal density. The rotifer egested 70-80% of the ingested nitrogen as particulate organic nitrogen (PON) and about 80% of the remaining assimilated nitrogen was utilized for reproduction. Low net growth efficiency (K₂) at high algal densities proved “superfluous feeding”. 20% of PON egested was incorporated in the rotifer again by bacteriovory, and 13% of that was remineralized to NH⁺₄ by bacteria. The PON was accumulated as a suspended or attached form in the culture vessel, which might cause an unstable environment. For a safety culture of the rotifer, removal of PON is an effective counter plan.