The predatory soil flagellate Heteromita globosa stimulates toluene biodegradation by a Pseudomonas sp.

A model food chain was established to investigate the influence of grazing by flagellates on bacteria degrading toluene in batch culture. The rate of toluene consumed by a Pseudomonas sp. strain PS+ (max. 0.37 fmol cell(-1) h (-1)) was significantly higher in the presence of the bacterivorous flagell ate Heteromita globosa (max. 1.38 fmol cell(-1) h-l). A maximum increase of up to 7.5 limes was observed in the rate of toluene consumed by these bact eria during exponential growth of this flagellate. Carbon conversion effici ency (CCE) of bacteria to flagellate biomass was estimated to be 33.4% base d on measured biovolumes and published values for carbon contents. However, the CCE for toluene-derived carbon was lower (max. 4.9%) when calculations were based on incorporation of [ring-U-C-14]toluene into biomass of flagel lates grazing on labelled bacteria. The findings suggest a potential role f or flagellates in bioremediation processes. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights r eserved.