Acidithiobacillus Sp Research Articles

Hybrid Filtration Process for Gas Desulfurization

A hybrid desulfurization process combining a physical filtration stage on cellular concrete (CC abiotic filter, called CCAF) and a biotrickling filter (called BTF) filled with expanded schist as packing material was used to remove high H2S concentrations from a synthetic gas containing dinitrogen (N2), dioxygen (O2) and H2S without the addition of a nutritive solution. Provided that small amounts of oxygen are present in the gas (1.2 ± 0.1% in volume), the global removal efficiency was 100%, and the global removal capacity reached 35 ± 2 gH2S m−3 h−1 for a total empty bed residence time (EBRT) of 120 s (CCAF + BTF). The resilience of the desulfurization process was demonstrated by applying severe changes in the H2S concentrations, from 160 to 1150 ± 20 mg m−3 for an EBRT = 120 s. According to the performances of the abiotic filter, which can decline over time due to the lifetime of the cellular concrete (137 days), the biotrickling filter reacted either as a refining system or as an efficient system able to treat significant H2S loading rates (up to 45 ± 3 gH2S m−3 h−1). Depending on the operating conditions, the increase in the pressure drops of the biotrickling filter (from 45 ± 3 to 234 ± 8 Pa m−1) highlighted biomass accumulation, especially extremophilic Acidithiobacillus sp. Considering the cellular concrete abiotic filter alone, removal capacities of up to 56 ± 3 gH2S m−3 h−1 were recorded for an EBRT of 60 s, demonstrating that gases such as landfill biogas or household biogas could be efficiently treated using this simple technique.

Differential Gene Expression and Bioinformatics Analysis of Copper Resistance-Related Gene afe_1948 from Acidithiobacillus sp. L1

Acidithiobacillus sp. L1, isolated from a coal mine in Agan Town, Lanzhou City, was introduced in this study. The gene afe_1948 relevant to copper resistance from the test bacterial strain was cloned and transformed into Escherichia coli BL21 (DE3) for heterologous prokaryotic expression, and analyzed by SDS-PAGE to evaluate its optimal expression conditions in E. coli. The expressions of afe_1948 in the presence of copper or cadmium were detected by qRT-PCR. The bioinformatics online analysis software was used to predict the physicochemical properties, structural features, functional domains, and possible metabolic pathways of the protein encoded by afe_1948. The result indicated that putative product AFE_1948 is a stable hydrophilic protein that locates on the cytoplasmic membrane or outside the cell. The gene afe_1948 is 1320 bp in length and encodes a total of 439 amino acids. In the experiment, the target gene was noticed to be very sensitive to copper and cadmium. Exposure to different Cu2+ concentration (0.05, 0.1, and 0.2 mol/L) resulted in the up-regulation of relative mRNA expression levels of afe_1948 in Acidithiobacillus sp. L1 by 2, 4, and 11-fold compared with the control, respectively. Similarly, the relative mRNA expression levels when exposed to Cd2+ at 0.02, 0.04, and 0.06 mol/L were increased by 2, 11, and 23-fold, respectively. To further understand the function of the gene, the variation of resistance to Cu2+ or Cd2+ after transferring into the recipient strain was examined by overexpression analysis. In the presence of 1.0 mmol/L Cu2+ or 0.2 mmol/L Cd2+, the highest relative expression levels regarding AFE_1948 were respectively determined to be more than 23% or close to 25% in recombinant E. coli cells. The assay demonstrated that the biomass of recombinant cells decreased significantly in the presence of Cu2+ or Cd2+ with different concentrations, but the content of intracellular AFE_1948 was enhanced, which may be contributed to a strong induction by the increase of the quantity of heavy metals entering into the cell and introduction of the resistance-related gene.

Treatment of mixed waste-gas containing H2S, dichloromethane and tetrahydrofuran by a multi-layer biotrickling filter

Biotrickling filter could be used for the abatement of volatile inorganic compounds (VICs) and volatile organic compounds (VOCs) simultaneously, a multi-layer biotrickling filter (MLBTF) system was constructed to lift the contradiction of pH between VICs degrader and VOCs degrader. The pH levels of the bottom, middle, and top layers of the MLBTF were controlled at 4.5, 6.0, and 7.5, respectively. Biological removal of ternary mixed hydrogen sulfide (H2S), tetrahydrofuran (THF), and dichloromethane (DCM) was conducted for 120 days. The result indicated that H2S was mainly removed in the bottom layer, the THF and DCM were mainly removed in the middle layer. The removal efficiency of 200 mg/L H2S, 100 mg/L THF, and 100 mg/L DCM were all exceeded 95% with an empty bed residence time of 35 s. The maximum elimination capabilities of H2S, THF, and DCM were 52.5, 26.7, and 17.2 g/(m3·h) respectively. Results from polymerase chain reaction denaturing gradient gel electrophoresis revealed that the dominant microorganisms in the bottom layer of MLBTF were Methylosinus sp. and Acidithiobacillus sp. The Pseudomonas sp., Achromobacter sp., and Methylobacterium sp. remained dominant throughout the operation in the middle and top layers. These findings demonstrated that the proposed method can effectively enhance the performance of VICs and VOCs removal by controlling pH and microbial community in each layer of the MLBTF. It is believed that this work provides a new insight into the biological removal of VOCs by the MLBTF.

Enhancement of manganese extraction in a biochar-enriched bioleaching column with a mixed culture of indigenous bacteria

Abstract. Retnanimgrum E, Wilopo W, Warmada IW. 2021. Enhancement of manganese extraction in a biochar-enriched bioleaching column with a mixed culture of indigenous bacteria. Biodiversitas 22: 2949-2955. Biochar can improve manganese ore extraction during bioleaching by inducing redox reactions and providing a porous matrix for bacterial attachment. In this research, the effect of variations in biochar concentration on the performance of a bioleaching column with a mixed culture of Acidithiobacillus sp. KL3 and Bacillus niacini KB3B1 were studied comprehensively for 30 days. Addition of 0.4% biochar resulted in 89% manganese extraction. Bioleaching with biochar promoted the oxidation of sulfur and yielded high sulfate concentrations, much better pH, and excellent oxidation–reduction potential conditions. The bacteria in the mixed culture survived and adapted to the extreme column environment by releasing extracellular polymeric substance, as evidenced by the sharp increase in the content of the material in the column to 135.7 mg/g over 30 days of incubation. The synergistic effect of the bacteria in the mixed culture greatly contributed to the mechanism of manganese extraction in the column, as indicated by changes in relative bacterial abundance, which is related to bacterial community succession during bioleaching. The relative abundance of B. niacini KB3B1 gradually increased and peaked at 30% over 9 days of measurements. By comparison, the abundance of Acidithiobacillus sp. KL3 first decreased over 9 days of bioleaching and then increased to a maximum of 80% in the final stages of the process. This finding reveals that biochar addition could enhance the mechanisms of bioleaching and improve the yield of manganese extraction.

RNA transcript response by an Acidithiobacillus spp. mixed culture reveals adaptations to growth on arsenopyrite.

Biooxidation of gold-bearing refractory mineral ores such as arsenopyrite (FeAsS) in stirred tanks produces solutions containing highly toxic arsenic concentrations. In this study, ferrous iron and inorganic sulfur-oxidizing Acidithiobacillus strain IBUN Ppt12 most similar to Acidithiobacillus ferrianus and inorganic sulfur compound oxidizing Acidithiobacillus sp. IBUNS3 were grown in co-culture during biooxidation of refractory FeAsS. Total RNA was extracted and sequenced from the planktonic cells to reveal genes with different transcript counts involved in the response to FeAsS containing medium. The co-culture's response to arsenic release during biooxidation included the ars operon genes that were independently regulated according to the arsenopyrite concentration. Additionally, increased mRNA transcript counts were identified for transmembrane ion transport proteins, stress response mechanisms, accumulation of inorganic polyphosphates, urea catabolic processes, and tryptophan biosynthesis. Acidithiobacillus spp. RNA transcripts also included those encoding the Rus and PetI proteins involved in ferrous iron oxidation and gene clusters annotated as encoding inorganic sulfur compound metabolism enzymes. Finally, mRNA counts of genes related to DNA methylation, management of oxidative stress, chemotaxis, and motility during biooxidation were decreased compared to cells growing without mineral. The results provide insights into the adaptation of Acidithiobacillus spp. to growth during biooxidation of arsenic-bearing sulfides.

Study on Microbiologically Induced Corrosion of Concrete in Sewer Waste Water

Concrete infrastructures that make up the sewer system exposed to sewer wastewaters are often subjected to microbial corrosion. The activity of sulfur-oxidizing bacteria Acidithiobacillus sp leads to the formation of biogenic sulfuric acid. The biogenic sulfuric acid plays a very vital role in sulfate attack on concrete leading to loss of concrete mass and deterioration. This paper presents the results of a laboratory study of concrete biodegradation by the activity of SOB A.thiooxidans. Concrete samples were immersed in real sewer wastewater under laboratory conditions for 14 months. Changes in chemical composition, weight loss, and sulfate concentration variation in the laboratory sewer were investigated. The influence of biogenic sulfuric acid on biocorrosion of concrete samples was determined in terms of weight loss, formation of corrosion by-products and bioleaching of Ca and Si ions leachates. The weight loss varied in the range 0.031 – 0.263 mm/yr. Changes in sample morphology and by-products formed were observed by X-ray diffraction and SEM methods. The results of morphologic changes showed the formation of gypsum and ettringite with corrosion progression.

Newly Isolated Acidithiobacillus sp. Ksh From Kashen Copper Ore: Peculiarities of EPS and Colloidal Exopolysaccharide.

A novel strain of an iron- and sulfur-oxidizing bacterium was isolated from a natural biotope at Kashen copper ore (Martakert Province, Republic of Artsakh). The strain is able to grow and oxidize ferrous ions in the range of pH 1.4–2.6 with optimal pH 2.0. The optimal temperature for growth is 35°C. Acidithiobacillus sp. Ksh has shown the highest activity for pyrite oxidation among other strains. It also demonstrated high activity in oxidation for copper and copper-gold bearing ores (Armenia). The isolate Acidithiobacillus sp. Ksh was identified as Acidithiobacillus ferrooxidans based on phylogenetic and physiological studies. Comparative studies of EPS production by cells grown on ferrous ions or pyrite were carried out. The chemical composition of capsular and colloidal EPS produced by Acidithiobacillus (At.) ferrooxidans Ksh were revealed to be proteins and carbohydrates. Exosaccharide produced by At. ferrooxidans Ksh is present mainly as polysaccharide in contrast to Leptospirillum (L.) ferriphilum CC, which is oligosaccharide. The structural difference of colloidal particles of these polysaccharides was due to the degree of hydration of the saccharide molecules.

Effect of the Met148Leu mutation on the structure and dynamics of the rusticyanin protein from Acidithiobacillus sp. FJ2

The rusticyanin protein, a blue monomeric copper protein type-1, is one of the main components in the iron-electron transfer chain of the Acidithiobacillus ferrooxidans, and is the product of the rus gene expression. Herein, first the bacterial DNA of Acidithiobacillus sp. FJ2 was extracted. Then, the rus gene sequence and the sequence amino acid rusticyanin protein were determined. The Met148Leu mutation increased the oxidase activity of the rusticyanin protein, thereby enhancing the efficiency of the bioleaching process by bacteria Acidithiobacillus ferroxidans. Met148Leu mutation was created in the rusticyanin protein, then molecular dynamics (MD) simulations and structural analysis were performed. The MD analysis of the wild-type and mutant protein demonstrated a slight instability in the mutant protein and significant instability in the active site of the mutant protein. The usefulness of this study is the genetic manipulation of the native Acidithiobacillus sp. FJ2 bacterium, which can boost the bioleaching efficiency of the bacterium to some extent, and investigating its effects on the structure of a mutant protein using computational methods.

Gene expression response of mutagenic breeding of Acidithiobacillus sp. FJ2 to different concentrations of uranium low grade ore

Acidithiobacillus ferrooxidans ( At. f ) is a bacterium involved in the bioleaching process . In the present study, we investigated the effects of Acidithiobacillus sp. FJ2 induced with diethyl sulfate (DES) as mutagen on the bioleaching of low grade uranium ore. The comparison was carried out within 5, 10, 15, 25 and 50% uranium ore pulp densities in the bioleaching system. The impact of the induction of Acidithiobacillus sp. FJ2 was determined by Eh and pH values, concentrations of Fe 2+ and uranium extraction rates at 24 h intervals. The results showed that DES with 0.8% may lead to an obvious change on bacteria leading to improvement of bioleaching capability in 5, 10, 15% pulp densities. However, the bioleaching activity of the original bacteria was more efficient than DES-induced bacteria at 25 and 50% pulp densities. The gene expression results in 0.8% DES treated bacteria indicated that the bacteria attempt to adjust in the bioleaching systems (with different pulp densities) through decreased cyc2 and increased rus , cyc1 and coxB levels. These results suggest that uranium may induce oxidative stress in the wild and treated strains in the high pulp density, while the bacteria tried to survive and gain more energy from the iron oxidation. However, when the amount of uranium increased, the mutants couldn’t cope up woth the enhanced stress in 25 and 50% pulp densities. It may be due to inhibitory effect of uranium toxicity on adaptive processes which may change the trends.

BIOLOGICAL SOLUBILIZATION OF SOME METALS BY A NEW ACIDITHIOBACILLUS SPECIES ISOLATED FROM A MODERATE SULFUR HOT SPRING

A chemolithotrophic bacterium was isolated from sulfur hot spring. According to phenotypic traits and 16-23S rDNA intergenic spacer region analysis, the isolate was identified and named as Acidithiobacillus sp. MR39, which was a gram-negative, rod- shape and non-motile bacterium. The strain was able to grow in a synthetic liquid medium supplemented with the mineral ore as the source of energy. The optimum conditions were found to be within initial pH range of 2.0-2.5, at 34±1˚C and with shaking at 120 rpm. The bacterium had a remarkable potential for mineralization of 88% iron, 75% copper, 59% zinc, 59% nickel and 40% cobalt upon their growth in the liquid media. After adapting the bacterial cells to copper ions in 100 mM for 5-day incubation, biorecovery of Cu increased about 10% comparing to unadapted cells that are able to dissolve approximately 15% of total cu of mineral concentrate. Considering the finding in this study, the strain MR39 offers a great prospect for in situ extraction of metals from various ores along with other indigenous bacteria that can grow under ambient conditions.

Pyrolusite Bioleaching by an Indigenous <i>Acidithiobacillus</i> sp KL3 Isolated from an Indonesian Sulfurous River Sediment

The manganese bioleaching process of pyrolusite from Kliripan, Indonesia using Acidithiobacillus sp KL3 was investigated. The influence pulp densities of pyrolusite (0.01, 0.02, 0.03 and 0.05 g/cm3) on the bioleaching processes were studied for 16 days. The reduction on pH values, the increasing of oxidation-reduction potential (ORP), sulfate and manganese concentration were analyzed. The manganese bioleaching mechanism of pyrolusite by the strain was monitored using Scanning Electron Microscope-Energy Dispersive-X-ray Spectroscopy (SEM-EDX). The results indicated that 0.02 g/cm3 of pyrolusite was considered to be the optimal pulp density for manganese bioleaching process. During this process, pH values decreased, furthermore resulted in increasing of ORP, the concentration of sulfate and manganese. SEM-EDX analysis clearly showed the evidence of directly bacterial cell attachment into the surface of pyrolusite. Extracellular polymeric substances (EPSs) were further founded on that surface. Sulfur elemental was oxidized by the strain which was then confirmed of resulting in solubilized manganese.

Sequencing of the rus gene before and after the mutation with DES in the bacterial Acidithiobacillus sp. FJ2

Sequencing of the rus gene before and after the mutation with DES in the bacterial Acidithiobacillus sp. FJ2

STUDY ON THE USE OF ACIDOPHILIC IRON OXIDIZING BACTERIA FOR DISSOLVING IRON FROM LOW-GRADED CHALCOPYRITE ORES

Biomining is a microbiological-based approach to extract minerals from ores without adding acids and other extraction chemicals. Having biological nature, the process is considered environmental friendly and tends to be applied more widely nowadays, especially for low-graded ores, for which chemical extraction is no longer efficient. In this study, two iron oxidizing bacterial strains Acidithiobacillus sp. IOB1 and Leptospirillum sp. IOB2 originated from mining sites in Vietnam were used in laboratory leaching experiments for the recovering minerals from low-graded chalcopyrite ores. The obtained results showed that both strains could significantly accelerate the leaching process, the highest iron dissolution rate was estimated for 0.83 g×kg-1×d-1 within two weeks of incubation with strain IOB2, about 30 % and 50 % respectively higher than leaching with strain IOB1 or control without bacteria, respectively. The iron extraction from ores was also evidenced by EDX analyses comparing the ore particles before and after incubation with the bacteria. Microscopic observation of DAPI-stained ore particles also showed high cell density attached to the particles, instead of freely moving in the liquid extract. Furthermore, FISH analyses using a specific probe for the g-Proteobacteria GAM42a revealed that only ~50 % of DAPI-stained cells were Acidithiobacillus sp. IOB1 – like in the leaching experiment with this train as starting culture, indicating that other bacterial species have developed and contributed to the metal dissolution here; however very rare positive signals were observed in leaching experiment with strain IOB2 as starting culture or the control without added bacteria. Thus, the acidophilic iron oxidizing strains Acidithiobacillus sp. IOB1 and Leptospirillum sp. IOB2 could serve as potential microbial sources for the development of biologically based approaches to extract minerals from ores, especially for those having low mineral contents.

The toxicity of graphene and its impacting on bioleaching of metal ions from sewages sludge by Acidithiobacillus sp.

The increasing production of graphene raised concerns about their releasing into sewage sludge, however, there is little information about graphene impacting on the growth of bacteria and hence their bioleaching of metal ions from sewages sludge. In this study, we reported that Acidithiobacillus sp., isolated from sewages, were used to bioleach Cu2+ and Zn2+ from sewages sludge in the presence of graphene. The negative effect on the growth of Acidithiobacillus sp. and dose-dependent were observed in presence of graphene, where the optical density (OD420) of the culture decreased from 0.163 to 0.045, while the bioleaching efficiency of Cu2+ (70%–16%) and Zn2+ (80%–48%) were also reduced when the graphene dose decreased from 50 mg L−1 to 1 mg L−1. Furthermore, scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed that the direct contacts between graphene and cell at 1 mg L−1 graphene caused cell membrane disruption, while Acidithiobacillus sp. grew better by forming dense biofilms around the suspended graphene at a 50 mg L−1. LIVE/DEAD staining further demonstrated that almost no live cells were detected at 1 mg L−1 graphene. The toxicity of graphene could generally be explained by depending on the concentration of graphene. The new findings provide an insight into dose dependence, which impacted on the growth of Acidithiobacillus sp. and their bioleaching of metal ion from sludge.

Molecular Regulatory Network Involved in Biofilm Structure Development by <i>Acidithiobacillus</i> <i>thiooxidans</i> Includes Pel Exopolysaccharide Machinery

The Acidithiobacillus genus plays a relevant role in bioleaching. The molecular understanding of biofilm formation has been pointed out to design biological strategies to improve the efficiency of this industrial process and to prevent environmental damages caused by acid mine/rock drainages. In Acidithiobacillus spp., the molecular mechanisms involved in biofilm formation are currently emerging. The second messenger cyclic diguanylate (c-di-GMP) appears as a key player for biofilm formation by Acidithiobacillus sp. Here, results obtained from genomic analysis to characterize c-di-GMP pathway in At. thiooxidans are reported. Intracellular levels of c-di-GMP have been previously measured and data indicated that they are higher in adhered cells than planktonic ones. During the course of characterization of c-di-GMP effectors, a complete pel-like gene cluster has been identified in At. thiooxidans. By using total RNA obtained from planktonic and adhered sulfur-grown cells, transcriptomic analysis revealed that pelA belonging to the pel-like gene cluster is overexpressed in adhered cells. Moreover, genetic experiments were performed to compare wild type and null-mutant strains of At. thiooxidans for assessing the role of Pel exopolysaccharide. All together, the results obtained suggest a specific role for Pel machinery in the attachment to solid energy substrates by At. thiooxidans.

Physiological and comparative genomic analysis of Acidithiobacillus ferrivorans PQ33 provides psychrotolerant fitness evidence for oxidation at low temperature

Friendly environmental hydrometallurgy at low temperatures is principally promoted by Acidithiobacillus ferrivorans. Until recently, the synergy between cold tolerance and the molecular mechanism of ferrous iron (Fe2+) oxidation was unknown. In the present paper, we conducted a physiological and comparative genomics analysis of the new strain A. ferrivorans PQ33 to elucidate the oxidation mechanism at low temperatures, with emphasis placed on trehalose and the Rus operon. PQ33 exhibited a doubling time of 66.6 h in Fe2+ at pH 1.6 and 63.6 h in CuS at 5 °C. Genomic island (GI) identification and comparative genome analysis were performed with four available genomes of Acidithiobacillus sp. The genome comprised 3,298,172 bp and 56.55% GC content. In contrast to ATCC Acidithiobacillus ferrooxidans strains, the genome of A. ferrivorans PQ33 harbors one GI, which contains a RusB gene. Moreover, five genes of peptidyl-prolyl cis–trans isomerase (PPIases) were observed. Furthermore, comparative analysis of the trehalose operon suggested the presence of a horizontal transfer event. In addition, comparison of rusticyanin proteins revealed that RusB has better intrinsic flexibility than RusA. This comparison suggests psychrotolerant fitness and supports the genetic canalization of A. ferrivorans PQ33 for oxidation at low temperature.

Effect of metal sulfide pulp density on gene expression of electron transporters in Acidithiobacillus sp. FJ2.

In Acidithiobacillus ferrooxidans, one of the most important bioleaching bacterial species, the proteins encoded by the rus operon are involved in the electron transfer from Fe2+ to O2. To obtain further knowledge about the mechanism(s) involved in the adaptive responses of the bacteria to growth on the different uranium ore pulp densities, we analyzed the expression of the four genes from the rus operon by real-time PCR, when Acidithiobacillus sp. FJ2 was grown in the presence of different uranium concentrations. The uranium bioleaching results showed the inhibitory effects of the metal pulp densities on the oxidation activity of the bacteria which can affect Eh, pH, Fe oxidation and uranium extractions. Gene expression analysis indicated that Acidithiobacillus sp. FJ2 tries to survive in the stress with increasing in the expression levels of cyc2, cyc1, rus and coxB, but the metal toxicity has a negative effect on the gene expression in different pulp densities. These results indicated that Acidithiobacillus sp. FJ2 could leach the uranium even in high pulp density (50%) by modulation in rus operon gene responses.

Improved chalcopyrite bioleaching by Acidithiobacillus sp. via direct step-wise regulation of microbial community structure

A direct step-wise regulation strategy of microbial community structure was developed for improving chalcopyrite bioleaching by Acidithiobacillus sp. Specially, the initial microbial proportion between Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was controlled at 3:1 with additional 2g/L Fe2+ for faster initiating iron metabolism. A. thiooxidans biomass was fed via a step-wise strategy (8–12th d) with the microbial proportion 1:1 for balancing community structure and promoting sulfur metabolism in the stationary phase. A. thiooxidans proportion was further improved via another step-wise feeding strategy (14–18th d) with the microbial proportion 1:2 for enhancing sulfur metabolism and weakening jarosite passivation in the later phase. With the community structure-shift control strategy, biochemical reaction was directly regulated for creating a better balance in different phases. Moreover, the final copper ion was increased from 57.1 to 93.2mg/L, with the productivity 2.33mg/(Ld). The novel strategy may be valuable in optimization of similar bioleaching process.

Microbial solubilization of phosphorus from phosphate rock by iron-oxidizing Acidithiobacillus sp. B2

Procedures for solubilization of phosphorus from insoluble phosphates by acidophilic autotrophs and heterotrophs are considered to be research subjects of great importance in sustainable soil management, and could become, in the future, an alternative to current expensive methods of industrial fertilizer production. Furthermore, this biological production of fertilizer can be considered to be more environmentally friendly than current production methods.The object of this study was to investigate the possibility of phosphorus leaching from phosphate rock apatite using sulphuric acid generated from pyrite by iron-oxidizing Acidithiobacillus sp. B2, and to test the possible application of the mixture of these two minerals to produce a natural phosphate fertilizer.Iron-oxidizing Acidithiobacillus sp. B2 was isolated from copper sulphide mine wastewater (Lake Robule) in Bor, Serbia. The bacterium was identified by 16SrDNA oligonucleotide sequence and characterized using matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS).The leaching experiment was carried out in laboratory conditions at 28°C for a period of four weeks.The results showed that up to 34.5% of the inorganic phosphorus was leached from the test mixture when in suspension with iron-oxidizing Acidithiobacillus sp. B2, while at the same time, the degree of leaching from a control suspension (without iron-oxidizing Acidithiobacillus sp. B2) was only up to 3.8%.Due to its low cost and environmental acceptance, treatment of soil with phosphate minerals in combination with pyrite and acidophilic iron- and sulphur-oxidizing bacteria could become an attractive and alternative way to improve the quality of alkaline soils.

Insights into the enhancement mechanism coupled with adapted adsorption behavior from mineralogical aspects in bioleaching of copper-bearing sulfide ore by Acidithiobacillus sp.

In this study, two typical bioleaching strains (A. ferrooxidansandA. thiooxidans) were employed for exploring the enhancement mechanism of the adapted adsorption behavior in the bioleaching of copper-bearing sulfide ore.