Amoebal growth in soil microcosms: a model system of C, N, and P. Trophic dynamics

Associations of terrestrial bacteria and amoebae provide a model system for understanding element dynamics mediated by trophic relationships in soil ecosystems. A Pseudomonas sp. and Acanthamoeba sp. were chosen for inoculation into soil sterilized with propylene oxide after screening bacterial and amoebal isolates from blue grama [Bouteloua gracilis (H.B.K.) Lag.] rhizospheres for compatibility and activity. Carbon, nitrogen, and phosphorus uptake and release were monitored in noninoculated, bacterial, and bacterial‐amoebal microcosms for incubation periods up to 30 days. Amoebal systems mineralized significantly more of these elements than systems with bacteria alone. Microbial phosphorus measurements also reflected the heavy amoebal grazing pressure.