EXAMINATION OF LIPOPOLYSACCHARIDE (O-ANTIGEN) POPULATIONS OF THIOBACILLUS-FERROOXIDANS FROM 2 MINE TAILINGS

Net acid-generating capacities of 39.74 kg of H2SO4 per ton (ca. 0.05 kg/kg) (pH 2.68) for the Lemoine copper mine tailings (closed ca. 8 ye ars ago; located 40 km west of Chibougamau, Quebec, Canada) and 16.07 kg of H2SO4 per ton (ca. 0.02 kg/kg) (pH 3.01) for the Copper Rand tai lings (in current use and 50 km distant [east] from those of Lemoine) demonstrate that these sulfide tailings can support populations of aci dophilic thiobacilli. Oxidized regions in both tailings environments w ere readily visible, were extremely acidic (Lemoine, pH 2.36; Copper R and, pH 3.07), and provided natural isolates for our study. A 10% (wt/ vol) oxalic acid treatment, which solubilizes both ferric sulfate and ferric hydroxide precipitates (B. Ramsay, J. Ramsay, M. deTremblay, an d C. Chavarie, Geomicrobiol. J. 6:171-177, 1988), enabled the recovery of intact bacterial cells from the tailings material and from liquid synthetic medium for lipopolysaccharide analysis. No viable cells coul d be cultured after this oxalic acid treatment. Sodium dodecyl sulfate -polyacrylamide gel electrophoretic profiles of lipopolysaccharides ex tracted from the Lemoine tailings were complex, indicating a heterogen eous population of Thiobacillus ferrooxidans. Six T. ferrooxidans subs pecies as identified by lipopolysaccharide analysis (i.e., lipopolysac charide chemotypes) were eventually isolated from a total of 112 cultu res from the Lemoine tailings. Using the same isolate and lipopolysacc haride typing techniques, we identified only a single lipopolysacchari de chemotype from 20 cultures of T. ferrooxidans isolated from the Cop per Rand tailings. This homogeneity of lipopolysaccharide chemotype wa s much different from what was found for the older Lemoine tailings an d may reflect a progressive lipopolysaccharide heterogeneity of Thioba cillus isolates as tailings leach and age.