Oxidation of micronized elemental sulphur in soil

The rate of oxidation of micronized elemental sulphur in three soils was measured over a range of temperatures between 2 and 20°C. Temperature had a marked effect with a Q₁₀ (temperature coefficient) between 1.9–3.1. The period for 50% oxidation varied between 6–10 days at 20°C to between 36–42 days at 2°C. All the oxidation curves showed an initial lag. At 20°C the oxidation rate was four times that of flowers of sulphur and was related to the smaller particle size. Additives (wetting and dispersing agents) in the commercial micronized sulphur preparation used (‘Thiovit’) were inhibitory at high concentrations but stimulatory at low concentrations. The significance to field conditions is discussed.     

Effects and limitations of elemental sulphur applications for enhanced phytoextraction

The application of elemental sulphur (S) to heavy metal contaminated soils is a strategy to increase metal extraction by plants. Here, we examined to which degree the efficiency of phytoextraction could be enhanced by increasing the S application rate on afield where S had already been applied for 6 years. For this purpose, the field experiment was continued for another two years doubling the S application rate on half of the S treatment plots, while continuing application at the previous rate on the other half. Doubling the application rate significantly accelerated the dissolution of calcite and the decrease in soil pH and also increased cadmium (Cd) and zinc (Zn) uptake by sunflower and tobacco. But even in a best-case-scenario remediation of the site would still take more than a century. The results indicate that we reached the maximum potential of S application to enhance metal phytoextraction on the study site. Further decrease in pH by additional S applications would bear an excessive risk of decreasing yields and increasing metal leaching out of the root zone.     

Solid media with elemental sulphur for detection of sulphuroxidizing microbes

Two solid media containing finely dispersed elemental sulphur and permitting autotrophic growth of sulphur-oxidizing organisms are described. On these media, colonies of sulphur-oxidizing cells are surrounded by a clear zone. A facultative S-oxidizingStreptomyces was isolated with the new technique.     

Analysis of the elemental sulfur bio-oxidation by Acidithiobacillus ferrooxidans with sulfur K-edge XANES

Elemental sulfur bio-oxidation by the typical acidophilic sulfur-oxidizing microbe Acidithiobacillus ferrooxidans was investigated by using the technique of sulfur K-edge XANES spectroscopy. Our results showed that the majority of elemental sulfur altered by A. ferrooxidans was dissolved into the organic phase containing carbon disulfide, while a part of it floated. The fitted results of sulfur K-edge XANES spectrum of the floated sulfur showed that the floating part of the elemental sulfur powder was converted to polymeric sulfur and the relative concentration of sulfur in cyclo-octasulfur S₈ and polymeric sulfur was 37.2 and 62.8%, respectively. It seems that the cyclo-octasulfur is converted to the polymeric sulfur and this appears to be necessary for oxidation of elemental sulfur by A. ferrooxidans. The results have important implications for our understanding of the mechanisms for bio-oxidation of elemental sulfur.     

Microbial oxidation of elemental sulphur in brown soil

Plant and Soil - Brown soil formed from loamy clay was examined for its ability to produce sulphate from added elemental suphur. At higher rates of sulphur applications the pH of a slightly acid...     

The influence of oxygen concentration in liquid medium on elemental sulphur oxidation by Thiobacillus thiooxidans

Rate of elemental sulphur biooxidation by Thiobacillus thiooxidans bacteria in continuous culture with nutrient circulation was determined for oxygen concentration in liquid in the range 1–17?mg/dm³ for temperature range 19–40?°C, pH from 1.5 to 4.5 and for CO₂ concentration above 110?mg/dm³. Equation describing the influence of above mentioned parameters on the rate of sulphur oxidation was presented.     

Preliminary proteomic analysis of Thiobacillus ferrooxidans growing on elemental sulphur and Fe2+ separately

Thiobacillus ferrooxidans is one of the most important bacterium used in bioleaching, and can utilize Fe2+ or sulphide as energy source. Growth curves for Thiobacillus ferrooxidans have been tested, which show lag, logarithmic, stationary and aging phases as seen in other bacteria. The logarithmic phases were from 10 to 32 hours for Thiobacillus ferrooxidans cultivated with Fe2+ and from 4 to 12 days for Thiobacillus ferrooxidans cultivated with elemental sulphur. Differences of protein patterns of Thiobacillus ferrooxidans growing on elemental sulphur and Fe2+ separately were investigated after cultivation at 30 degrees C by the analysis of two-dimensional gel electrophoresis (2-DE), matrix-assisted laser desorption/ ionization (MALDI)-Mass spectrometry and ESI-MS/MS. From the 17 identified protein spots, 11 spots were found more abundant when growing on elemental sulphur. By contrast 6 protein spots were found decreased at elemental cultivation condition. Among the proteins identified, cytochrome C have been previously identified as necessary elements of electron-transferring pathway for Thiobacillus ferrooxidans to oxidize Fe2+; ATP synthase alpha chain and beta are expressed increased when Thiobacillus ferrooxidans cultivated with Fe2+ as energy source. ATP synthase Beta chain is the catalytic subunit, and ATP synthase alpha chain is a regulatory subunit. The function of ATPase produces ATP from ADP in the presence of a proton gradient across the membrane.     

Effect of removal of unattached cells on the bio-oxidation rate of pyrite in a fluidised bed reactor

Summary The relative significance of attached and unattached bacteria in bio-oxidation was assessed using a fluidised bed reactor. The unattached bacteria were removed from the system after different times in batch culture. Following wasout, the concentration of unattached bacteria recovered rapidly. This was ascribed to desorption of attached bacteria rather than growth of free, unattached bacteria. Throughout the cell depletion and repopulation phase, the rate of pyrite oxidation remained fairly constant.     

Biological oxidation of elemental sulphur added to three composts from different feedstocks to reduce their pH for horticultural purposes

The biological oxidation of elemental sulphur (S(o)) added to three alkaline composts prepared with a range of organic wastes (CC, melon crop residues; MC, mixed manures; and BC, pine bark) to reduce their pH was studied. The titration curves showed that to achieve an equivalent pH drop, compost CC needed a larger dose of S(o) than did composts MC and BC. The acidification efficiency was high in the three composts (53%), but the pH reduction obtained from the titration curves in MC and BC composts was lower than expected. S(o) oxidation in amended composts was found to be related to pH and CaCO(3) content decreases, and to the rise in CaSO(4) and electrical conductivity levels. A remarkable increase in the autotrophic bacteria population and a slight increase in heterotrophic bacteria along with S(o) oxidation were recorded. Actinomycetes, fungi and yeasts were not affected by the addition of S(o) to composts.     

高硫高砷金精矿生物预氧化条件优化

摘要:【目的】研究温度以及返回液添加量对体系中氧化效果以及金(Au)氰化浸出率的影响。【方法】针对某高硫高砷金精矿建立了一套连续生物预氧化体系(氧化时间6 d),比较不同的温度(40℃和45℃)和返回液添加量(0和600mL)对生物预氧化效果的影响:间隔8 h连续测定氧化体系中的氧化液、氧化渣以及氰化渣中的总Fe、总S、总As以及SO4 2－和Au含量;并用16S rRNA基因克隆文库的方法对体系中的浸矿菌群结构进行分析。【结果】结果显示,提高温度和添加氧化返回液都会改变体系:升高温度在一定程度上提高了体系的氧化程度,主要表现为显著降低了尾渣中总铁、总硫含量,显著提高了尾渣中的S6 + 比例,并且降低前三槽氧化体系的耗碱量;投加返回液则会降低体系的氧化程度,主要表现为显著提高了尾渣金品位和铁含量,显著降低了尾渣中的S6 + 以及Au 浸出率;Dissimilarity和DCA结果表明温度变化对体系的影响更为显著;氧化过程中的Au 浸出率、硫氧化率以及As 去除率,三者互为显著正相关;克隆文库结果显示,该浸矿菌群主要包括3类细菌: Acidithiocacillus caldu (71%)、Leptospirillum ferriphilum (23%)和Sulfobacillus thermosulfidooxidans(6%),基于97%相似性的OTU覆盖率达93.67%。【结论】研究结果表明,相对于添加返回液,温度变化会更显著的改变体系反应效率。提高体系温度有利于矿物的氧化,而添加返回液会降低Au浸出率。本文首次研究了连续生物预氧化过程中温度梯度和返回液添加对体系的影响,本研究结果对中温生物预氧化工业生产的工艺优化、降低工业运行成本具有重要的指导意义。     

Effects of elemental sulphur on the activity of adenylate kinase and performance of isolated rabbit heart

The experiments performed have shown that elemental sulphur inhibited only cytoplasmic isoenzyme of adenylate kinase without having any effect on mitochondrial isoenzyme. Effect of sulphur is related to its reaction with SH-groups of enzyme. Sulphur also by 50% inhibited cytoplasmic adenylate kinase in intact myocardium during perfusion of isolated rabbit heart. Under this circumstances the amplitude of contractions is diminished but perfusate flow is increased. Thus elemental sulphur must be considered as a new specific SH-reagent and vasodilator drug.     

Tools for characterizing the whole-cell bio-oxidation of alkanes at microscale

This article describes the first reported microwell whole-cell bioconversion using a water immiscible substrate that matches the specific activity and yield achieved in a 1.2 L stirred tank bioreactor. Maximum yields of 0.6 g/L(total) 1-dodecanol achieved in 24 h compare favorably to 0.28 g/L(total) 1-dodecanol after 48 h obtained in a stirred tank reactor. Using the microwell platform we present a rapid and systematic approach to identify the key bottlenecks in the bio-oxidation of long-chain alkanes using Escherichia coli expressing the alkane hydroxylase (alkB) complex. The results indicate that mass transfer rates limit productivity in the n-dodecane bio-oxidation system, rather than inherent enzyme activity. Furthermore, substrate solubility, oxygen availability and glucose concentration act cooperatively to affect the amount of by-product, dodecanoic acid. Optimizing these factors using response surface methodology enabled specific yields of 1-dodecanol to increase eightfold and overoxidation to dodecanoic acid to be reduced from 95% to 55%. This resulted in specific activities of 10.4 μmol/min/g(dcw) on n-dodecane; approximately 50% of the 21 μmol/min/g(dcw) obtained with n-octane. For the first time, this in vivo rate difference is within the range reported for the purified enzyme. Finally, the results obtained also provide strong evidence that the mechanism of E. coli interaction with alkanes is mainly via uptake of alkanes dissolved in the aqueous phase rather than by direct cell-droplet contact.