Bacterial leaching of single sulfide minerals and polymetallic sulfide ores was operated in shake flasks and small-scaled columns.The results show that bioleaching of jamesonite is not accessible,the iron extraction rate of pyrrhotite bioleaching reaches 98.2% after 26 d,and the zinc extraction rate of marmatite bioleaching reaches 92.3%,while the corresponding iron extraction reaches only 13.6% after 29 d.Pulp density has a significant effect on metal extraction of pyrrhotite and marmatite bioleaching.The corresponding metal extraction rate decreases with the increase of pulp density.For the polymetallic sulfide ores,zinc extraction of 97.1% is achieved after bioleaching in shake flasks for 10 d,while only 7.8% is obtained after bioleaching in small-scaled column.Analytical results of scanning electron microscopy(SEM) and energy dispersive X-ray analysis(EDX) reveal that large amount of calcium sulfate is formed on the mineral surface.
以活性炭作为含碳金矿中碳质物的替代物,研究了球红假单胞菌对其的降解转化及吸金能力的影响.通过正交试验确定了球红假单胞菌降解活性炭的最优工艺组合:粒度<74μm、炭浆质量分数5%、降解时间14 d、菌液用量1 m L/100 m L,此时活性炭的降解率高达28.35%.金吸附性试验表明,球红假单胞菌可使活性炭的吸金能力降低11.46%.球红假单胞菌使活性炭的微晶结构发生变化;一些芳环结构被破坏;含氧基团和芳香族结构的数量增多.这说明球红假单胞菌在降低碳质物劫金性方面是一种有效微生物.
Acidithiobacillus caldus plays an important role in commercial bioleaching.To understand how NaCl stress adaptation occurs in A.caldus,we grew A.caldus strain SM-1 in media containing high NaCl concentrations.SM-1 grew at concentrations of up to 1.0-mol L^(-1)NaCl,but growth was severely inhibited at higher concentrations.Proteomic analysis showed that SM-1 used multiple strategies to respond to NaCl stress.In addition to several heatshock proteins,enzymes involved in proline biosynthesis increased under NaCl stress.In addition,two DNA-binding proteins and a third protein of unknown function(Atc_(1291)),which was subsequently identified as a putative single-stranded DNA-binding protein,were up-regulated in the presence of NaCl stress.These DNA-binding proteins might play a role in response to osmotic stress.Atc_(1291)was cloned and expressed in Escherichia coli.Surprisingly,we found that E.coli BL21/pET28a-atc_(1291)grew to higher cell densities than E.coli BL21/pET28a,regardless of NaCI stress.Homologs to Atc_(1291)were identified in several groups of Proleohacleria.The role of Atc_(1291)in enhancing cell growth needs further investigation.
Xu GuoChengying JiangYuanming LuoMingjiang ZhangAnsgar PoetschShuangjiang Liu
