Jarosite-type precipitates mediated by YN22, Sulfobacillus thermosulfidooxidans, and their influences on strain
(School of Resources Processing and Bioengineering, Central South University, Changsha 410083, China )
Abstract: 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) of S. thermosulfidooxidans was cultured in a medium containing Fe2+ 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 Fe2+, the precipitate yield of jarosite-type compounds and the population density between the two groups of cultures. The group with glass beads has a 6 h faster Fe2+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 Fe2+ 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 Fe2+ oxidation ability of YN22 when a precipitate content over 4 g/L is used.
Key words: strain YN22; Sulfobacillus thermosulfidooxidans; precipitate; jarosite; ammoniojarosite