MA

thesisThere were at least two types of chemoautotrophic thiobacilli found in the leaching streams of Bingham Canyon min dump. One of these organisms oxidizes free sulfur to sulfuric acid which reaction is its energy reaction. This organism is very similar to Thiobacillus thiooxidans. The other organism oxidizes ferrous to ferric ion as its initial energy reaction and is similar to thiobacillus ferrooxidans. These two bacterial strains complement each other in that T. thiooxidans produces acid which keeps the ferric ion produced by T. ferrooxidans in solution, thereby forming an effective acidic ferric sulfate leaching solution for copper minerals. In addition to these two types of chemoautotrophs, a yeast-like organism was found in every location of the Bingham mine dump waters. The cell biology and physiology of these yeast-type organisms were studied. It was found not to be a chemoautotrophic, but an acidophilic heterotroph. The microbial population in the mine water samples suggests the coexistence of a balanced ecological system in which carbon fixation is dependent on chemoautotrophic bacteria. Acidophilic heterotrophs, utilizing organic matter as their energy and carbon source, are acting to keep the organic content of leach waters at a low concentration favorable to the development of chemoautotrophs. Three different counting techniques, such as a Petroff-Hausser counting technique, the silica gel plate counting technique and the radioisotope labeling technique for the enumeration of the chemoautotrophic thiobacilli were studies. Of these methods, the direct microscopic counts were the only ones found to be satisfactory as the most rapid and relatively reliable method of estimating this type of cell numbers. Statistical evaluation of Petroff-Hausser counting technique was also made to prove the reliability of this method. The correlation between the conversion of ferrous to ferric ion and bacterial growth were studies. It was shown that a given amount of conversion of ferrous to ferric ion over a given time period corresponded to a given increase in the bacterial population. The distribution of Thiobacillus ferrooxidans and their ecological environment in the Bingham mine dump were investigated. It was noted that there was a relationship between the numbers of T. ferrooxidans in leaching systems and the chemical reactions which were known to occur in this process