• BMB Reports
• /
• 제38권5호
• /
• pp.545-549
• /
• 2005

Acidithiobacillus ferrooxidans is one of the most important bacterium used in bioleaching, and can utilize $Fe^{2+}$ or sulphide as energy source. Growth curves for Acidithiobacillus ferrooxidans under phosphate starvation and normal condition have been tested, showing lag, logarithmic, stationary and aging phases as seen in other bacteria. The logarithmic phases were from 10 to 32 hours for Acidithiobacillus ferrooxidans cultivated with normal cultivating condition and from 20 to 60 hrs for Acidithiobacillus ferrooxidans cultivated phosphate starvation. Differences of protein patterns of Acidithiobacillus ferrooxidans growing in case of normal or phosphate starvation were separately investigated after cultivation at $30^{\circ}C$ by the analysis of two-dimensional gel electrophoresis (2-DE), matrix-assisted laser desorption/ionization (MALDI)-Mass spectrometry. There were total 6 protein spots identified, which were Recombination protein recA, RNA helicase, AP2 domain-containing transcription factor, NADH dehydrogenase I chain D, Hyothetical protein PF1669, and Transaldolase STY3758. From the 6 identified protein spots, 3 proteins were found to be decreased in expression at the cultivating condition of phosphate starvation, while another three upregulated.

• Environmental Engineering Research
• /
• 제7권4호
• /
• pp.199-206
• /
• 2002

• 자원리싸이클링
• /
• 제30권2호
• /
• pp.14-23
• /
• 2021

실제 광산 현장에서 적재된 광석으로부터 미생물에 의한 중금속 용출 가능성을 알아보고자 호산성 미생물인 Acidithiobacillus ferrooxidans와 Acidithiobacillus thiooxidans를 이용하여 초기 산성조건에서 복합금속광(Pb-Zn-As 광석)을 대상으로 60일에 걸쳐 중금속 용출실험을 진행하였다. 용출 시험 초기에는 초기 산성 조건에 의해 용출되는 소량의 중금속 이외에 미생물의 활성화로 인한 중금속의 용출은 거의 검출되지 않았다. 그러나 A. thiooxidans이 시료의 환경에 적응한 20일 이후, 중금속 용출량이 급격히 증가하였으며, 독성 물질로 위험성이 높은 비소와 철, 아연이 각각 최대 2800 mg/L, 3700 mg/L, 그리고 2050 mg/L로 용출되는 것을 확인하였다. 반면 A. ferrooxidans을 주입한 반응기와 미생물을 주입하지 않은 대조실험 결과에서는 약간의 아연을 제외한 기타 중금속 용출이 전혀 발생하지 않았다. 이를 통해 산성조건의 광산 현장에서 토착 미생물에 의한 황화광 산화 및 중금속의 용출 가능성을 확인할 수 있었고, 본 연구에 사용된 고농도 비소를 함유한 광석 시스템에서는 A. ferrooxidans 보다 A. thiooxidans에 의한 중금속 용출이 더욱 위협적이라는 것을 확인하였다.

• Journal of Microbiology and Biotechnology
• /
• 제12권2호
• /
• pp.268-272
• /
• 2002

Kinetic experiments on the biological oxidation of $Fe^{2＋}$ by Acidithiobacillus ferrooxidans were conducted by measuring the total organic carbon content. The total organic carbon in the solution was determined with different initial concentrations of $Fe^{2＋}$(4, 9, 15, and 20 mg/ml). The growth of At. ferrooxidans and substrate utilization were described by the Monod expression. The total organic carbon was found to be an indicator of the biomass concentration and thus may be effectively utilized for estimating cell growth rates in kinetic model development.

• Journal of Microbiology and Biotechnology
• /
• 제18권7호
• /
• pp.1298-1307
• /
• 2008

In this study, we investigated the inhibition effects of single and mixed heavy metal ions ($Zn^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Cd^{2+}$) on iron oxidation by Acidithiobacillus ferrooxidans. Effects of metals on the iron oxidation activity of A. ferrooxidans are categorized into four types of patterns according to its oxidation behavior. The results indicated that the inhibition effects of the metals on the iron oxidation activity were noncompetitive inhibitions. We proposed a reduced inhibition model, along with the reduced inhibition constant ($\alpha_i$), which was derived from the inhibition constant ($K_I$) of individual metals and represented the tolerance of a given inhibitor relative to that of a reference inhibitor. This model was used to evaluate the toxicity effect (inhibition effect) of metals on the iron oxidation activity of A. ferrooxidans. The model revealed that the iron oxidation behavior of the metals, regardless of metal systems (single, binary, ternary, or quaternary), is closely matched to that of any reference inhibitor at the same reduced inhibition concentration, $[I]_{reduced}$, which defines the ratio of the inhibitor concentration to the reduced inhibition constant. The model demonstrated that single metal systems and mixed metal systems with the same reduced inhibitor concentrations have similar toxic effects on microbial activity.

• BMB Reports
• /
• 제39권2호
• /
• pp.178-182
• /
• 2006

Four strains of Acidithiobacillus ferrooxidans with different iron oxidation capacity were isolated from different mine drainage stations. The 16S rRNA gene of these strains were cloned and sequenced. Based on our sequences analysis on the four strain and the data on the other strains deposited in Genbank, all A. ferrooxidans may be classified into three phylogenetic groups. The analysis data showed that nucleotide variables (signature sites) were detected in 21 positions, and most of them were found in the first 800bp from 5' terminal except position 970 and 1375. Interestingly, the first 13 signature sites were located in two main regions:the first region (position 175-234) located in V2 while the second region (position 390-439) were detected in constant region between V2 and V3. Furthermore, the secondary structure and minimal free energy were determined in two regions among strains of three groups. These results may be useful in characterizing the microevolutionary mechanisms of species formation and monitoring in biohydrometallurgical application.

• 한국지반환경공학회 논문집
• /
• 제13권4호
• /
• pp.5-11
• /
• 2012

폐광산의 산성배수(AMD)는 황철석을 비롯한 다른 금속 황화물의 산화를 통해 발생한 폐광산의 산성배수는 환경오염의 원인 중 하나이다. 본 연구에서는 이러한 폐광산의 산성배수가 생성되는 과정에서 산화미생물의 관여 정도를 알아보고, 이를 억제할 수 있는 방법에 대해여 살펴보았다. 산성배수 발생에 영향을 미치는 산화미생물로 Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans을 선정하였으며, 이 산화미생물의 활성 및 생장 속도를 측정하였으며, 이산화염소$(ClO_2)$, NaCl, 그리고 계면활성제(ASOR-770) 를 산발생 억제제로 이용하여 실험을 진행하였다. 실험 결과 10ppm 이산화염소가 가장 효과적인 억제제였으며, 산화미생물의 활성도와 생장도를 20% 까지 감소시켜주었다.

• Journal of Microbiology and Biotechnology
• /
• 제21권2호
• /
• pp.124-128
• /
• 2011

Ferredoxin is a typical iron-sulfur protein that is ubiquitous in biological redox systems. This study investigates the in vitro assembly of a [$Fe_2S_2$] cluster in the ferredoxin from Acidithiobacillus ferrooxidans in the presence of three scaffold proteins: IscA, IscS, and IscU. The spectra and MALDI-TOF MS results for the reconstituted ferredoxin confirm that the iron-sulfur cluster was correctly assembled in the protein. The inactivation of cysteine desulfurase by L-allylglycine completely blocked any [$Fe_2S_2$] cluster assembly in the ferredoxin in E. coli, confirming that cysteine desulfurase is an essential component for iron-sulfur cluster assembly. The present results also provide strong evidence that [$Fe_2S_2$] cluster assembly in ferredoxin follows the AUS pathway.

• Advances in environmental research
• /
• 제3권3호
• /
• pp.199-206
• /
• 2014

Dewatering is an extremely important step in wastewater treatment process to reduce the final sludge volume in order to minimize the cost of sludge transportation and disposal. In the present study, the effect of different sludge solids content (1, 2 and 3.8%) on the dewaterability of anaerobically digested sludge using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was studied. The pH reduction rate was higher during initial process in the sludge having low solids content, but after 48 h of bioleaching, similar pH of below 3 was observed with all the different solids content. Bio-oxidation rate of $Fe^{2+}$ was initially higher in sludge with low solids content, but 100% $Fe^{2+}$ was oxidized within 60 h in all the three treatment levels. Compared to the control, specific resistance to filtration was reduced by 75, 78 and 80% in the sludge with a solids content of 1, 2 and 3.8% respectively, showing improvement in dewaterability with an increase in sludge solids content. Sludge effluent quality and sludge settling rate were also improved in treatments with higher solids content after the bioleaching process.

• 대한의생명과학회지
• /
• 제13권2호
• /
• pp.105-110
• /
• 2007

Aspartyl-tRNA synthetase (AspRS) exists in two different forms with respect to tRNA recognition. The discriminating enzyme (D-AspRS) recognizes only tRNA$^{Asp}$, while the non-discriminating one (ND-AspRS) also recognizes tRNA$^{Asn}$ and therefore forms both Asp-tRNA$^{Asn}$ and Asp-tRNA$^{Asp}$. Plus primary sequence distinguishes two general groups of AspRS. There is a predominantly bacterial-type, larger AspRS (about 580 aa) in addition to a shorter archaeal/eukaryotic type (about 430 aa). In vivo data made clear that discriminating and non-discriminating enzymes exist in both groups. The determinants in the protein sequence responsible for tRNA discrimination are not hewn. The AspRS from Acidithiobacillus ferrooxidans might be suggested ND-AspRS fur missing of AsnRS in genomic sequencing data. Therefore, we analyzed the AspRS from A. ferrooxidans with in vitro aminoacylation assay with E. coli unfractionated tRNA, in vivo missense suppression assay with tipA34 mutant and Northern hybridization with probes which were specific with tRNA$^{Asp}$ or tRNA$^{Asn}$. The AspRS from A. ferrooxidans produced more Asp-tRNA than that from E. coli. Only aspS gene from A. ferrooxidans suppressed trpA34 strain in minimal media without tryptophan. Only AspRS from A. ferrooxidans showed mischarged Asp-tRNA$^{Asn}$ band. Therefore, AspRS from A. ferrooxidans is definitely ND-AspRS.