Ferrobacillus ferrooxidans: a chemosynthetic autotrophic Bacterium.

Investigations into the cause and control of the production of sulfuric acid in effluents of coal mines, and the effects of such effluents upon streams were begun in 1946.1 Working and abandoned mines of Western Pennsylvania alone contribute an estimated million tons of sulfuric acid per year to the drainage area of the Ohio River. A field survey of mine drainage and receiving streams was inaugurated, and the waters were examined by chemical and bacteriological procedures. The sulfuric acid enters the drainage as ferrous sulfate, FeSO4, which is derived from finely dispersed pyrite, FeS2, in the coal and associated rock strata. By inference, sulfur-oxidizing bacteria were considered as participating in the oxidation of such pyritic materials, but this was proved to be an erroneous supposition (Leathen, Braley, and McIntyre, 1953). However, in an examination of the drainage from the Bradenville Mine in 1947, the change from ferrous to ferric sulfate was observed to increase more rapidly than could be accounted for by absorption of atmospheric oxygen. From such rapidly oxidizing effluents, it became evident that chemosynthetic autotrophic bacteria were associated with bituminous coal mines. One of these microorganisms, described in 1954 (Leathen and Braley), was definitely shown to oxidize ferrous to ferric sulfate and was given the specific name, Ferrobacillus ferrooxidans. Physiological studies of this bacterium have been continued, and it is the purpose of this report to describe further this autotroph, which is indigenous in all bituminous coal regions. Such ferruginous waters, being highly acidic, restrict the autotrophic population and usually kill the heterotrophs which normally inhabit streams. To account for the high acidities of some bituminous coal mine drainage, Powell and Parr