Leaching Experiments with Some Enrichment Cultures in the Absence of Nutritive Salts

In this report, we describedo bservationso f behavioro n the long time leachinge xperimentsu sings ome enrichmentc ultures.Our study was made by a conbinationo f the followingtw oexperiments;(1) a experimentw ithout containingn utrient except for energy source, which is the same as a method applied usually in a basic study of the pure culture, (2) a long time leachinge xperimentu nder pH 2 with a enrichmentc ulture.The enrichment cultures were used for FeSO4oxidation and S0leaching in the absence of nutritive salts. The relations between treatment time and product amount of Fe3+or SO42-were linear.The followingo bservationws ere obtaineda bout the behavioro f the enrichmentc ulturesi n these experiments.1) It was supposed that the drop of apparent oxidation velocity of Fe2+at the high values of the ratio [Fe3+]/[Fe2+] resultedf rom the regulatorym echanismo f bacteria.2) From the result of leachinge xperimentso f elementals ulfur, it was recognizedth at a enrichmentc ulture kept a constant activity for a long time.