• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.1
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• pp.48-52
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• 2000

An autotrophic sulfur oxidizer, Thiobacillus sp. ASWW-2, was isolated from activated sludge, and its sulfur oxidation activity was characterized. Thiobacillus sp. ASWW-2 could oxidize elemental sulfur on the broad range from pH 2 to 8. When 5-50 g/L of elemental sulfur was supplemented as a substrate, the growth and sulfur oxidation activity of Thiobacillus sp. ASWW-2 was not inhibited. The specific sulfur oxidation rate of strain ASWW-2 decreased gradually until sulfate was accumulated in medium up to 10 g/L. In the range of sulfate concentration from 10 g/L to 50 g/L, the sulfur oxidation rate could keep over $2.0g-S/g-DCW{\cdot}d$. It indicated that Thiobacillus sp. ASWW-2 has tolerance to high concentration of sulfate.

• Microbiology and Biotechnology Letters
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• v.34 no.4
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• pp.338-341
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• 2006

The growth characteristics of sulfur-oxidizing bacteria, Acidithiobacillus thiooxidans AZ11, MET, and TAS were investigated in mineral salt media supplemented with elemental sulfur of 1$\sim$50 g $L^{-1}$. The sulfur oxidation rates of A. thiooxidans. MET and TAS increased highly with increasing sulfur concentration up to 10 g L$^{-1}$, but the rates increased slowly in sulfur concentration over 10 g L$^{-1}$. A. thiooxidans AZ11 showed the parallel increase of sulfur oxidation rate until sulfur concentration increased up to 40 g L$^{-1}$. The maximum sulfur oxidation rates (V$_{max}$) of AZl1, MET and TAS were 1.88, 1.38 and 0.43 g S L$^{-1}$ d$^{-1}$, respectively. The maximum specific growth rates (${\mu}_{max}$) of AZ11, MET, and TAS were 0.33 d$^{-1}$, 0.30 d$^{-1}$ and 0.45 d$^{-1}$, respectively. Although MET and TAS couldn't grow at sulfate concentration of 40 g L$^{-1}$, AZ11 could grow in the presence of 58 g L$^{-1}$ sulfate, the final oxidation product of elemental sulfur.

• Journal of Microbiology and Biotechnology
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• v.15 no.4
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• pp.716-721
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• 2005

The role of an effective microbial species is critical to the successful application of biological processes to remove sulfur compounds. A bacterial strain was isolated from the soil of a malodorous site and identified as Burkholderia spp. This isolate was able to oxidize thiosulfate to sulfate, with simultaneous pH decrease and accumulation of elemental sulfur. The specific growth rate and the sulfate oxidation rate using the thiosulfate basal medium were $0.003 h^{-1}\;and\;3.7 h^{-1}$, respectively. The isolated strain was mixotrophic, and supplementation of $0.2\%$ (w/v) of yeast extract to the thiosulfate-basal medium increased the specific growth rate by 50-fold. However, the rate of sulfate oxidation was more than ten times higher without yeast extract. The isolate grew best at pH 7.0 and $30^{\circ}C$, and the sulfate oxidation rate was the highest at 0.12 M sodium thiosulfate. In an upflow biofilter, the isolated strain was able to degrade $H_2S\;with\;88\%$ efficiency at 8 ppm and 121/h of incoming gas concentration and flow rate, respectively. The cell density at the bottom of the column reached $3.2{\times}10^8$ CFU/(g bead) at a gas flow rate of 121/h.

• Journal of Microbiology and Biotechnology
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• v.26 no.11
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• pp.1871-1880
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• 2016

Bio-oxidation is an effective technology for treatment of refractory gold concentrates. However, the unsatisfactory oxidation rate and long residence time, which cause a lower cyanide leaching rate and gold recovery, are key factors that restrict the application of traditional bio-oxidation technology. In this study, the oxidation rate of refractory gold concentrates and the adaption of microorganisms were analyzed to evaluate a newly developed two-step pretreatment process, which includes a high temperature chemical oxidation step and a subsequent bio-oxidation step. The oxidation rate and recovery rate of gold were improved significantly after the two-step process. The results showed that the highest oxidation rate of sulfide sulfur could reach to 99.01 % with an extreme thermophile microbial community when the pulp density was 5%. Accordingly, the recovery rate of gold was elevated to 92.51%. Meanwhile, the results revealed that moderate thermophiles performed better than acidophilic mesophiles and extreme thermophiles, whose oxidation rates declined drastically when the pulp density was increased to 10% and 15%. The oxidation rates of sulfide sulfur with moderate thermophiles were 93.94% and 65.73% when the pulp density was increased to 10% and 15%, respectively. All these results indicated that the two-step pretreatment increased the oxidation rate of refractory gold concentrates and is a potential technology to pretreat the refractory sample. Meanwhile, owing to the sensitivity of the microbial community under different pulp density levels, the optimization of microbial community in bio-oxidation is necessary in industry.

• Journal of Korean Society for Atmospheric Environment
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• v.3 no.1
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• pp.41-46
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• 1987

Adsorption and reaction studies were made for the catalytic oxidation in aqueous slurries of activated carbon at room temperature and atmospheric pressure. In order to analyze the reaction rate, the mechanism was assumed by the steps of nonhomogeneous catalytic reaction. The experimental result show that oxidation rate was controlled by the reaction between adsorbed molecular oxygen and sulfur dioxide on the catalyst surface. Ar room temperature, the equat5ion of reaction rate was given as $ro_2 = 2.49 \times 10^{-7} P_O_2^{0.604}$.

• KSBB Journal
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• v.16 no.5
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• pp.466-473
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• 2001

A bacterium was isolated from soils in Suwon, Korea for the purpose of H$_2$S removal using a biofilter system. The isolate was gram-negative, rod-shaped, catalase-positive, motile, and the isolated bacterium showed a positve in utilizing energy sources including citrate, mannitol, sucrose, fructors, and trehalsoe. Based on its biochemical characteristics it was identified as Burkholderia(Pseudomonas) cepacia. The growth rate of the bacterium in thiosulfate medium with yeast extract was 0.15 hr$\^$-1/ and generation time was 4.6 hr. The cell productivity was 8.05 mg/L$.$h and the isolate grew logarithmically up to 12 hr. The maximum rate of sulfur oxidation was 0.18 g-S/L$.$h. The optimum pH and temperature for the growth of the bacterium were 7.0 and 30$\^{C}$, respectively. The pH range for the growth of B. cepacia was 5.0-8.0. The oxidation rate of thiosulfate was lowered by a substrate thiosulfate when the concentration was higher than 0.12 M. both growth rate and sulfur oxidation rate of Burkholderia(Pseudomonas) cepacia was enhanced about 1.5 times with the addition of 0.2% yeast extract. The removal of hydrogen sulfide was investigated by immobilized B. cepacia with Ca-alginate. The maximum rate removal for H$_2$S was 6.25 g$.$㎤ $.$h$\^$-1/ when 12 L/h of flow rate was supplied. From this study suggest the immobilized B. cepacia could have a potential for H$_2$S removal.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.3
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• pp.243-248
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• 1996

To find out the oxidation process of potential acid sulfate soil(PASS) along with time. the PASS were treated with lime and ammonia water to adjust soil pH in laboratory column condition. pH range of PASS showed 6.5 to 7.5. however, complete oxidized PASS by $H_2O_2$ showed 2.1 to 2.5. After pilling the PASS under the natural condition. oxidation occured slowly from surface of the pilled soil. The oxidation of PASS proceeded slowly when the soil was in submerged condition. but quickly in dried condition. The content of sulfide-sulfur in PASS sharply decreased after exposing to the air and the decreasing rate was greater in dried than in submerged condition. The content of sulfate-sulfur continuously decreased in submerged condition. but increased in dried condition. Contents of $Fe^{+{+}}$ and $Al^{+{+}}$ in PASS were generally increased with time and the increasing rate was greater in submerged than in dried condition. Liming to PASS was slowly acting to pH change and ammonia water caused fast pH change within a short period of time. The contents of sulfate-sulfur and exchangeable aluminum in drainage water decreased with time and the contents of sulfide-sulfur and ferrous iron were increased.

• Journal of Microbiology and Biotechnology
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• v.21 no.7
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• pp.753-756
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• 2011

A methane-oxidizing bacterium was isolated from the enriched culture of a landfill cover soil. The closest relative of the isolate, designated M6, is Methylocystis sp. Based on a kinetic analysis, the maximum specific methane oxidation rate and saturation constant were 4.93 mmol gdry cell $weight^{-1}{\cdot}h^{-1}$ and 23${\mu}M$, respectively. This was the first time a kinetic analysis was performed using pure methanotrophic culture. The methane oxidation by M6 was investigated in the presence of aromatic (m- and pxylene and ethylbenzene) or sulfur (hydrogen sulfide, dimethyl sulfide, methanthiol) compounds. The methane oxidation was inhibited by the presence of aromatic or sulfur compounds.

• Journal of Life Science
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• v.18 no.1
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• pp.9-15
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• 2008

Sulfur containing compounds in garlic have all be used as one of the traditional folk medicine as well as food source. The present study was performed to investigate the antioxidative compounds of 1-methyl-1-cysteine, dimethyl trisulfide and 2-vinyl-4H-1,3-dithiin. The antioxidative activity of sulfur containing compounds on human LDL was investigated by monitoring a thiobarbituric acid substances (TBARS). Sulfur containing compounds inhibited on oxidation of LDL mediated by $CuSO_4$ and macrophages in dose dependent manner with almost completely inhibition at $80{\mu}g/ml$. Antioxidant activities of sulfur containing compounds on LDL oxidation were 2-vinyl-4H-1,3-dithiin, 1-methyl-1-cysteine, and dimethyl trisulfide in order. Inhibitory effects of sulfur containing compounds on oxidation of LDL mediated by $CuSO_4$ and macrophages were degraded at much greater rate than native LDL, the LDL oxidation process was arrested as shown by the lower conjugated dienes formation at the concentration of $60{\mu}g/ml$. Sulfur containing compounds in garlic revealed at high antioxidative activity at low physiological concentration for human LDL oxidation in vitro specially, it was indicated that the antioxidative activity of 3-viny l-4H-1,2-dithiin was higher than that of the other sulfur containing compounds.

• Food Science of Animal Resources
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• v.35 no.1
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• pp.41-49
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• 2015

This study was performed to assess the antioxidant activity of Allium hookeri root extract (AHE) on lipid oxidation of raw sulfur-fed pork patties for 14 d of refrigerated storage. Different concentration of ethanol (0-100%) and time (1-12 h) were applied to determine the extraction condition. Water (0% ethanol) extraction for 1 h was selected as an optimal extraction condition of AHE for the following study showing the highest total phenolic content and total flavonoid content, as well as the strongest antioxidant activity. The 1% AHE (SP1), 3% AHE (SP2), and 0.05% ascorbic acid (SP3) were added into sulfur-fed pork patties against controls; SP0 (sulfur-fed pork patties with no AHE) and P0 (normal pork patties with no AHE). The pH values of P0 and SP0 significantly increased (p<0.05) than others on 14 d and redness of P0 showed the largest decrement during storage. P0 and SP0 showed higher production of conjugated dienes on d 7 than others (p<0.05). Thiobarbituric acid reactive substances (TBARS) values were decreased in proportion to the increased level of AHE on 14 d (p<0.05) resulting in higher TBARS values on P0 and SP0 (p<0.05) and the negative correlation between AHE level and TBARS were also demonstrated (r=-0.910, p=0.001). Therefore, the results suggest that AHE effectively retarded the lipid oxidation rate of sulfur-fed pork patties indicating the potential usage of AHE as a natural preservative.