Jarosite-type precipitates mediated by YN22, Sulfobacillus thermosulfidooxidans, and their influences on strain

To have a better understanding on the properties of the jarosite-type precipitate synthesized by Sulfobacillus thermosulfidooxidans, the evolution of the S. thermosulfidooxidans-mediated precipitation and the influence of the precipitate on this species, a newly isolated strain （YN22） ofS. thermosulfidooxidans was cultured in a medium containing Fe^2＋ as energy source under optimal conditions （pH 1.5, 53 ℃, 0.2 g/L yeast extract, 30 g/L Fe2SO4·7H2O and 170 r/min）, added with or without glass beads. Remarkable differences were found in the oxidation rate of Fe^2＋, the precipitate yield ofjarosite-type compounds and the population density between the two groups of cultures. The group with glass beads has a 6 h faster Fe^2＋ oxidation, 6 h earlier precipitation, 78% higher precipitate yield and much lower population density than those without glass beads. XRD, EDS, FTIR and SEM analysis reveals that the precipitates originated from both groups are a mixture of potassium jarosite and ammoniojarosite, with morphological features similar to the latter. The results of the test referring to influence of the precipitates on YN22 show that the precipitate from the group without glass beads has no apparent influence on Fe^2＋ oxidation rate of YN22 and only a limited influence on growth of the strain, whereas that from the group with glass beads remarkably inhibits the growth and Fe^2＋ oxidation ability of YN22 when a precipitate content over 4 g/L is used.