• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.1046-1054
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• 2001

Bioleaching is the process in which insoluble metal sulfide is oxidized by specialized iron- and/or sulfur-oxidizing lithotrophic bacteria in acidic, metal-rich environments. Most of these processes are carried out by the genus Thiobacillus. Three novel Thiobacillus strains (Thiobacillus thiooxidans AZ11, Thiobacillus thiooxidans MET, and thiobacillus thiooxidans TAS) associated with bioleaching have been isolated from soil and sludge (Korean patent No. 1999-0073060 for T. thiooxidans AZ11, Korean patent No. 1999-0005798 for T. thiooxidans MET, and Korean patent No. 1999-0073059 for T. thiooxidans TAS). A partial sequence of 16S ribosomal RNA gene (16S rDNA) and the entire sequence of 16S/23S intergenic spacer region (ISR) were determined in the three above novel strains and in Thiobacillus ferrooxidans ATCC19859 as a reference strain. When phylogenetic analysis was performed based on G+C contents and sequence alignments, T. ferroxidans ATCC19859 was found to be closely related to previously registered T. ferrooxidans strains in a monophyletic manner, while the three novel T. thiooxidans strains were classified in a paraphyletic manner. Close examination on the base composition of 16S/23S ISR revealed that the 5\` part (nucleotide residues 21-200) was specific for the genus Thiobacillus. On the other end, the 3\` part (nucleotide residues 201-520) showed specificity in T. ferrooxidans strains, but not in T. thiooxidans strains. These results suggest that the proximal and distal halves of 16S/23S could be used as a genetic marker for the identification of the genus Thiobacillus and the species T. ferrooxidans, respectively.

• Journal of the Korean GEO-environmental Society
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• v.13 no.4
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• pp.5-11
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• 2012

Acid mine drainage (AMD) is one of the most severe environmental problem that results from the oxidation of pyrite $(FeS_2)$ and various other metal sulfides. In this study, the influence of microorganism was tested on the process where AMD was released and the method to inhibit AMD generated by microorganisms at abandoned mine area. The activity and growth rate of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, common microorganisms affecting AMD occurrence, were measured. Chlorine dioxide $(ClO_2)$, NaCl, or surfactant (ASOR-770) was used as an inhibitor for working on activity and growth of microorganism. Among the three inhibitors, 10ppm of chlorine dioxide was the most effective inhibitor for AMD control due to the reduced the activity and growth of microorganisms by 20%.

• Journal of Ginseng Research
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• v.24 no.3
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• pp.107-112
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• 2000

One of the physiologically important ginseng diseases is red-colored phenomena (RCP) that is caused by accumulation of red-colored substances on the epidermis of ginseng roots. Although RCP severely deteriorates the quality of ginseng products, there has been little information on what red-colored substance is and how RCP occurs. Therefore, the heavy losses of cultivators and ginseng industry are suffering by RCP, For this reason, we have investigated with the morphochernical characteristics of RCP to find out main cause of it. The red-colored substances (RS) on the epidermis of red-colored ginseng (RCG) were examined using inverted light microscope, confocal laser scanning microscope (CLSM)and furier transform infrared (FT/IR) spectrometer. Red brown substances were accumulated in the cell wall of the epidermis from early stage to late stage of RCC. Especially, cell wall of the late stage of RCG was covered with the sub-stances with 80~ 130 fm thick. Therefore, the cell wall of RCG cannot protect the ginseng root cells from the mechanical damages, bacteria and fungi. To analyse red substances of roots, RS were isolated from epidermis of RCG and extracted using various solvents. RS is strongly insoluble but it was bleached by oxidizing agents including 12% (v/v) NaOCl. Therefore, RS was Presumed to make up of high chelation power. The proriles of FT/IR spectra or both healthy ginseng (HEG) and RCG showed a significant difference at two wavelength,2857 cm$\^$-1/(C-H) and 1032 cm$\^$-1/(S=O), respectively. Furthermore, absorption peak of 2857cm$\^$-l/ appears on the only epidermis of RCG. The other peak is shown lower absorption rate on the epidermis of RCG than that of healthy ginseng. Also, FT/IR spectra of the mixture of carboxym-ethylcellulose (CMC) and iron (Fe$\^$3+/) were very similar to RCG spectrum profiles. One of a interesting fact is that the contents of phenolic compounds at the epidermis of healthy ginseng were highest. The results of these experiments sup-port the RCP was closely related with the chemical interaction between inorganic elements (Fe) of rhizosphere and organic matters (cellulose, cellobiose, cell sap, etc.) of ginseng roots.

• KSBB Journal
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• v.11 no.2
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• pp.238-245
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• 1996

Microbial desulfurization characterlstics of a bituminous coal have been determined by using Thiobacillus ferrooxidans. The effects of process variables (such as coal pulp density, particle size and addition of surfactants) on pyrite removal have been investigated in both shake and airlift-bioreactor culture experiments. In shake experiments, pyrite could be removed over 78% for pulp densifies below 20% (w/v) and removed below 40% for pulp densities over 30% (w/v) in 8 days. Pyrite removal decreased with increasing pulp densities, and it also decreased sharply with increasing particle sizes. In airlift bioreactor experiments, pyrite at 50% (w/v) pulp density could be removed about 50%. Its value is much higher than 15% at the same pulp density in a shake experiment. With addition of surfactants, pyrite removal was enhanced in shake experiments significantly, whereas it was slightly decreased in an airlift bioreactor experiment.