• Journal of Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.144-149
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• 2006

As a strain EH741, having an excellent hexane degradability, was isolated from bacterial consortium using hexane as a sole carbon and energy source. EH741 was identified as a Rhodococcus sp. and the addition of a surfactant Pluronic F68(PF68), for increasing hexane solubility couldn't enhance the specific growth rate of the isolate EH741 n the mineral salt medium supplemented with hexane as a sole carbon source(hexane-BH medium). In the hexane-BH medium, the maximum specific growth rate(${\mu}_{max}$) of this strain was $0.04h^{-1}$, and the maximum hexane degradation rate($V_{max}$) and saturation constant($K_s$) were$161{\mu}mol{\cdot}g-DCW^{-1}{\cdot}h^{-1}$ and 10.5 mM, respectively. Rhodococcus sp. EH741 was one of excellent microorgamisms for hexane biodegradation processes.

• Journal of the Korea Organic Resources Recycling Association
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• v.22 no.1
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• pp.49-56
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• 2014

This study was conducted to investigate the biodegradation characteristics of swine and cattle using anaerobic batch tests. The results showed that the maximum methane production rate($MPR_{max}$) and acclimation time(AT) of swine were 46.7 mL $CH_4/g$ VS.d and 17.2 d, respectively. The $MPR_{max}$ and AT of cattle were 56.5% and 24.0% lower than those of swine. The characteristics of anaerobic biodegradation varied with livestock species but $MPR_{max}$ and AT increased linearly with the content of lipid. The $MPR_{max}$ and AT of cattle with content of lipid were more sensitive than those of swine.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.4
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• pp.131-137
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• 2007

In this study, the biodegradation test on lignocellulose under sulfate reducing conditions was carried out. In particular, the interaction between cellulose and lignin was investigated with various g-cellulose/g-lignin (C/L) ratios: 42.15, 4.59, 2.51, 1.14 and 0.7. It was shown that the rate of cellulose degradation decreased in proportion to the lignin content. Assuming first order degradation kinetics, the consequences of competitive inhibition were graphically shown for different C/L ratios. The relation between cellulose reduction rate and C/L ratio was expressed by logarithm function with a determination coefficient of 0.97. Lignocellulose reduction rate was also described as a logarithm function of C/L ratio showing a inhibition effect by lignin. In the mean time, the rate of lignin decomposition was higher at C/L ratio of 2.51 and 1.14 compared with C/L ratios of 4.59 and 0.7, indicating that excessive extra carbon source is not appropriate for lignin biodegradation.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.489-492
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• 2000

The eventual goal of this study is to elucidate roles of plant terpenoids (e.g., cymene, limonene and others) as natural substrates in the cometabolic biodegradation of PCBs and to develop an effective PCB bioremediation technology. The aim of this study was to examine how plant terpenoids, as natural substrates or inducers would affect the biodegradation of PCB congeners. Various PCB degraders that could grow on biphenyl and several terpenoids were tested for their PCB degradation capabilities. The PCB congener degradation activities were first monitored through resting cell assay technique that could detect degradation products of the substrate. The congener removal was also confirmed by concommitant GC analysis. The PCB degraders, Pseudononas sp. P166 and Caynebacterium sp. T104 were found to grow on both biphenyl and terpenoids ((S)-(-) limonene, p-cymene and ${\alpha}-terpinene$) whereas Arthrobacter B1B could not grow on the terpenoids as a sole carbon source. The strain B1B grown on biphenyl showed a good degradation activity for 4,4'-dichlorobiphenyl (DCBp) while strains P166 and T104 gave about 25% of B1B activity. Induction of degradation by cymene, limonene and terpine was hardly detected by the resting cell assay technique. This appeared to be due to relatively lower induction effect of these terpenoids compared with biphenyl. However, a subsequent GC analysis showed that the congener could be removed up to 30% by the resting cells of T104 grown on the terpenoids. This indicates that terpenoids, widely distributed in nature, could be utilized as both growth and/or inducer substrate for PCB biodegradation.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.3
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• pp.205-210
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• 2006

The widespread use and distribution of chloroethylene organic compounds is of serious concern owing to their carcinogenicity and toxicity to humans and wildlife. In an effort to develop active bacterial consortia that could be useful for bioremediation of chloroethylene-contaminated sites in Africa, 16 combinations of 5 dichloroethylene (DCE)-utilizing bacteria, isolated from South Africa and Nigeria, were assessed for their ability to degrade cis- and trans- DCEs as the sole carbon source. Three combinations of these isolates were able to remove up to 72% of the compounds within 7 days. Specific growth rate constants of the bacterial consortia ranged between 0.465 and $0.716\;d^{-1}$ while the degradation rate constants ranged between 0.184 and $0.205\;d^{-1}$ with $86.36{\sim}93.53\;and\;87.47{\sim}97.12%$ of the stoichiometric-expected chloride released during growth of the bacterial consortia in cis- and trans-DCE, respectively. Succession studies of the individual isolates present in the consortium revealed that the biodegradation process was initially dominated by Achromobacter xylosoxidans and subsequently by Acinetobacter sp. and Bacillus sp., respectively. The results of this study suggest that consortia of bacteria are more efficient than monocultures in the aerobic biodegradation of DCEs, degrading the compounds to levels that are up to 60% below the maximum allowable limits in drinking water.

• Journal of Wetlands Research
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• v.13 no.1
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• pp.129-137
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• 2011

The aim of this study is to evaluate the biodegradability of the micro-contaminant, clindamycin antibiotic, under nitrifying activated sludge (AS) condition. Based on the short-term clindamycin degradation batch test at an environmentally relevant concentration (10 ppb), clindamycin disappearance half-life ($t_{0.5}$) was estimated to be 9.1hrs under nitrification condition. However, biodegradation was slower (26.1 hrs) when nitrification was inhibited. Also, one clindamycin metabolite was detected under nitrification condition, but not under inhibited nitrification condition. Based on the mass spectra, the metabolite is suspected to be clindamycin-sulfoxide (m/z 441), which is known to have antimicrobial activity. The metabolite was not degraded during the long term batch study, suggesting that under the conditions tested, biodegradation of clindamycin in activated sludge systems is ineffective.

• KSBB Journal
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• v.24 no.5
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• pp.453-457
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• 2009

Contamination of marine environment with hazardous and toxic chemicals is more common these days. Bioremediation is the application of microorganism or microbial processes to degrade environmental contaminant. Because of low water solubility and volatility of diesel, bioremediation is more efficient than physical and chemical methods. The objective of this study is biodegradation of diesel in sea water by using Rhodococcus fascians which is isolated petroleum-contaminated soil. R. fascians was cultured on sea water containing diesel to determine the diesel degradability. Changes in biodegradability of diesel with various inoculum sizes, diesel concentrations, initial pH, and culture temperature were analyzed by TPH analysis using gas chromatography. The inoculum size 2% was effective for biodegrdation of diesel in sea water by R. fascians. When diesel concentration was 5%, the growth of cell was inhibited by the toxicity of diesel. The optimal temperature and initial pH for degradation of diesel in sea water were $27^{\circ}C$ and pH 8.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.1
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• pp.61-66
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• 2001

The aim of this study was to examine how plant terpenoids, as natural growth substrates or inducers, would affect the biodegradation of PCB congeners. Various PCB degraders that could grow on biphenyl and several terpenoids were tested for their PCB degradation capabilities. Degradation activities of the PCB congeners, 4,4-dichlorobiphenyl (4,4-DCBp) and 2,2-dichlorobiphenyl (2,2-DCBp), were initially monitored through a resting cell assay technique that could detect their degradation products. The PCB degraders, Pseudomonas ((S)-(-) limonene, p-cymene and $\alpha$-terpinene) whereas Arthrobacter sp. B1B could not grow on the terpenoids as a sole carbon source. The B1B strain grown on biphenyl exhibited good degradation activity for 4,4-DCBp and 2,2-DCBp, while the activity of strains P166 and T104 was about 25% that of the B1B strain, respectively. Concomitant GC analysis, however, demonstrated that strain T104, grown on (S)-(-) limonene, p-cymene and $\alpha$-terpinene, could degrade 4,4-DCBp up to 30%, equivalent to 50% of the biphenyl induction level. Moreover, strain T104 grown on (S)-(-) limonene, could also degrade 2,2-DCBp up to 30%. This indicates that terpenoids, widely distributed in nature, could be utilized as both growth and/or inducer substrate(s) for PCB biodegradation in the environment.

• Journal of the Korea Organic Resources Recycling Association
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• v.16 no.3
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• pp.46-51
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• 2008

The traditional view of the fate of lignin under anaerobic conditions is that it is recalcitrant because molecular oxygen is required for depolymerization. The presence of lignin is apparently the most important factor affecting the biodegradability of ligneous materials. The initial step in the degradation of ligneous material to smaller intermediates is catalyzed by enzymes secreted by microorganisms and is generally regarded as the rate limiting step in the microbial mineralization of organic matter. Biochemical methane potential (BMP) test, typically used to assess anaerobic biodegradability of liquid wastes with added nutrients and bacteria, have been adapted to assess initial biodegradation of ligneous material under anaerobic conditions. A method based on selective inhibition of microorganism activity, by 3% toluene, has been used to measure using the initial degradation rate of ligneous material and the accumulation of lignin-derived compounds.

• Korean Journal of Environmental Biology
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• v.25 no.3
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• pp.260-266
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• 2007

A thermophilic bacterium capable of poly (L-lactide)(PLLA) degradation was isolated from cultivating soil in Korea. The isolate was Gram positive rod-shaped bacterium, and was identified as Geobacillus caldoxylosilyticus based on the 16S rDNA sequence analysis. The strain proved to be a new PLLA degrading bacterium which has not been reported in the open literatures yet. The degradation activity of the strain was assessed in a sterilized compost inoculated with the strain under controlled compost condition at $58^{\circ}C$ for 40 days. The strain mineralized 66%, 57%, 41% and 40% of PLLA5000, PLLA11000, PLLA34000 and PLLA256000 whose weight average molecular weights were 5000, 11000, 34000 and 256000, respectively. Incorporation of 0.1% each of gelatin, yeast extract and ammonium sulfate in the compost containing PLLA256000 as a nutritional supplement raised the biodegradation activity by 27%, 13% and 10%, respectively. Increase of the inoculum size from $10^9cfu\;g^{-1}\;to\;10^{10}cfu\;g^{-1}\;and\;10^{11}cfu\;g^{-1}$ also enhanced the biodegradation activity by 14% and 20%, respectively.