DECOMPOSITION OF CELLS AND EMPTY SHELLS OF TESTATE AMEBAS (RHIZOPODA, TESTACEA) IN AN ORGANIC-ACID SOIL STERILIZED BY PROPYLENE-OXIDE FUMIGATION, AUTOCLAVING, AND GAMMA-RAY IRRADIATION

Testate amoebae were killed by propylene oxide fumigation, autoclaving, and gamma-ray irradiation of an organic acid soil. The soil was then incubated with a mixed bacterial inoculum. The decomposition of the cells and the empty shells was followed for 5 weeks by direct counts. No significant disappearance was observed for either the cells or the empty shells. The lack of decomposition during the time-course of the experiment can be explained by the high level of moisture in the soil and leads to two conclusions: (1) The mineralization of dead cells can be delayed if any other source of labile C is available (e.g., soluble C liberated by the treatment); (2) the validity of this measurement of the density, mortality and production of natural populations of testate amoebae is questionable.