THE GROWTH OF PROTOZOA IN STERILIZED SOIL .2. DYNAMIC OF THE CILIATE COMMUNITY

The ciliate community was investigated in laboratory microcosms using forest litter layers treated with either propylene oxide, autoclaving or gamma-irradiation and then amended with untreated soil samples. The subsequent growth of ciliates was followed for 28 days in each treatm ent, with regard to the dominant groups, i.e. colpodids, hypotrichs an d DI epanomonas sp. The result showed marked changes among the treatme nts. In fumigated soil, the population of colpodids increased rapidly after inoculation followed by hypotrichs 14 days later. In the autocla ved treatment, the growth of colpodids was rapid but trophozoites were observed only after 14 days. DI epanomonas sp. appeared from day 3 an d remained only as trophozoite form. The population of hypotrichs incr eased after 28 days. In the irradiated treatment, colpodids were the f irst to grow followed by Drepanomonas sp. from day 3 and hypotrichs fr om day 7. Numbers of colpodids was never significantly different betwe en treatments. Numbers of Drepanomonas sp. were always significantly l arger in autoclaved humus than in the order treatments and numbers of hypotrichs were larger on day 28 in irradiated humus. The different re sponses of the ciliate community, especially the successions of specie s are discussed.