• Korean Journal of Microbiology
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• v.37 no.1
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• pp.85-91
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• 2001

Biological treatment of benzene and toluene contaminated soil was investigated in laboratory microcosm of 16 different types for degrading benzene and toluene by indigenous bacteria. At the experimental conditions of the microcosms fast degrading benzene and toluene, moisture contents were 30% and 60% in a soil gap and content of powdered-activated carbon(PCA) for adhesion of benzene and toluene-degrading bacteria was 1% in total soil mass. At the conclusion of the shifted bacteria community, Case 6 and case 7 were operated until 10 days, and then the total cell number and the number of benzene and toluene degrading bacteria were investigated. The total cell number of Case 6 and Case 7 increased 488 fold and 308 fold of total indigenous cell, respectively. The number of benzene and toluene degrading bacteria increased and maintained the percentages occupied in pre-operating microcosm. Species of benzene and toluene degrading bacteria in microcosm changed from species of Gram negative bacteria to Gram positive bacterial species after soil exposed to benzene and toluene.

• Microbiology and Biotechnology Letters
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• v.16 no.5
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• pp.379-383
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• 1988

To evaluate the treatability of activated sludge induced by benzene with microorganisms, isolation and characterization of benzene-degrading microorganisms were carried out. Six bacterial isolates from the activated sludge were identified ; Pseudomonas fluorescens, Enterobacter agglomerans, Enterobacter cloacae, Klebsiella oxytoca, Citrobacter freundii and Klebsiella pneumoniae. P. fluorescens degraded 55% of benzene contained in the medium as a sole carbon source, E. cloacae 24%, E. agglomerans 41%, and K. oxytoca 32%. Optimal temperature, pH and benzene concentration for growth of P. fluorescens appeared to be 31$^{\circ}C$, pH 7.0, and 300mg benzene per liter. When the P. fluorescens was dominant in the activated sludge induced by benzene, the indicator protozoa was Aspidisca sp. When concentration of benzene was about 387mg per liter, the growths of Aspidisca sp. and Litonotus sp. were high. Protozoa, Litonotus sp. and Vorticella sp. did not grow over 1600mg of benzene per liter.

• Journal of Soil and Groundwater Environment
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• v.8 no.1
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• pp.42-47
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• 2003

A biofilter study was performed in order to remove mixed benzene and ethylene emitted from soil and groundwater remediation. In particular, more than 96% of ethylene was removed at residence times of 10～15 min, and the possibility of use of the biofilter was obtained. The benzene removal efficiency was achieved as much as 100% at residence times of 2～15 min. With a residence time of 15 min, the maximum elimination capacity of benzene and ethylene was 4.3 g/$\textrm{m}^3$hr and 1.4 g/$\textrm{m}^3$hr, respectively. The maximum elimination capacity of benzene was 3 times higher than that of ethylene. Carbon dioxide concentration decreased as residence times were lowered due to low ethylene degradation rate. The maximum carbon dioxide production rate of 3,169 [mg-$CO_2$/(g-${C_2}{H_4}$＋${C_6}{H_6$)] was investigated when benzene and ethylene were completely removed. It was found that dominant bacteria in the benzene-degrading microorganisms were identified as Bacillus mycoides and Pseudomonas fluorescens. Dominant bacteria in the ethylene-degrading microorganisms were identified as Pseudomonas putida and Pseudomonas fluorescens.

• Korean Journal of Microbiology
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• v.19 no.4
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• pp.179-185
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• 1981

Facultative psychrophilic bacteria utilizing SDBS (Sodium Dodecyl Benzene Sulfonate) as their carbon source were isolated in the Han River. All of these isolated faculatative psychrophilic bacteria were identified as Pseudomonas spp. The growth and biodegradation rates of Ps.fluorescens LP6, Ps. fluorescens LS6 and Ps. putida LC1 among 8 identified facultative psychrophilic bacteria were investigated with spectrophotometer. The specific growth rates of these three facultative psychrophilic bacteria at $25^{\circ}C$ were higher than those at any other temperatures. However, the final cell yields were the highest for cells grown at $5^{\circ}C$. The biodegradation of SDBS by Ps. fluorescens LP 6 was started at the stationary phase of cells. The biodegradation rate of SDBS by Ps. fluorescens LP6 was the highest when the cells were cultured at $25^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• v.17 no.12
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• pp.1976-1982
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• 2007

In the current studies, we characterized the degradation of a hot mixture of benzene and toluene (BT) gases by a thermophilic biofilter using polyurethane as a packing material and high-temperature compost as a microbial source. We also examined the effect of supplementing the biofilter with yeast extract (YE). We found that YE substantially enhanced microbial activity in the thermophilic biofilter. The degrading activity of the biofilter supplied with YE was stable during long-term operation (approximately 100 d) without accumulating excess biomass. The maximum elimination capacity ($1,650\;g{\cdot} m^{-3}{\cdot} h^{-1}$) in the biofilter supplemented with YE was 3.5 times higher than that in the biofilter without YE ($470\;g{\cdot} m^{-3}{\cdot} h^{-1}$). At similar retention times, the capacity to eliminate BT for the YE-supplemented biofilter was higher than for previously reported mesophilic biofilters. Thus, thermophilic biofiltration can be used to degrade hydrophobic compounds such as a BT mixture. Finally, 168 rDNA polymerase chain reaction-DGGE (PCR-DGGE) fingerprinting revealed that the thermophilic bacteria in the biofilter included Rubrobacter sp. and Mycobacterium sp.

• Korean Journal of Environmental Biology
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• v.19 no.1
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• pp.87-92
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• 2001

For the biological treatment of industrial wastewater containing high concentration of phenol, isolation and characterization of phenol - degrading bacterium were carried out. A bacterial strain P2 capable of degrading phenol was isolated from contaminated soils by enrichment culture technique and identified as the genus Rhodococcus by morphological, cultural, biochemical characteristics, and Biolog system. The optimal medium composition and cultural conditions for the growth and degradation of phenol by Rhodococcus sp. P2 were 0.1% of (NH$_4$)$_2$SO$_4$, 0.2% of KH$_2$PO$_4$, 0.25% of Na$_2$HPO$_4$ㆍ12$H_2O$, 0.2% of MgSO$_4$ㆍ7$H_2O$, and 0.008% of CaC1$_2$ㆍ2$H_2O$ along with initial pH 8.5 at 3$0^{\circ}C$. Rhodococcus sp. P2 could grow with phenol as the sole carbon source up to 1,800 ppm in batch cultures, but did not grow in medium containing above 2,000 ppm of phenol. When 800 ppm phenol was given in the optimal media, Rhodococcus sp. P2 completely degraded it within 24 h. Meanwhile, 1,800 ppm of phenol was degraded within 9 days. Rhodococcus sp. P2 could utilize toluene, n-hexane, xylene and benzene as sole carbon source .

• Journal of Microbiology
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• v.35 no.3
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• pp.193-199
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• 1997

From several industrial wastewaters, 14 bacterial strains which degrade benzene, toluene, o-xylene, m-xylene, or p-xylene (BTX) were obtained. These strains were characterized as to their species composition and the substrate range, kinetic parameters and the substrate interactions were investigated. Although BTX components have a similar chemical structure, isolated strains showed different substrate ranges and kinetic parameters. None of the strains could degrade all of BTX components and most of them showed an inhibition (Haldane) kinetics on BTX, BTX mixtures were removed under inhibitory substrate interactions with variation in the intensity of inhibition. For a complete degradation of BTX, a defined mixed culture containing three different types of patyways was constructed and all of the BTX components were simultaneously degraded with the totla removal rate of 225.69 mg/g biomass/h Judging from the results, the obtained mixed culture seems to be useful for the treatment of BTX-contaminated wastewater or groundwater as well as for the removal of BTX from the contaminated air stream.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.695-701
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• 2006

A toluene-degrading bacterial strain was isolated from a mixed culture that was maintained using toluene as a sole carbon and energy source. The isolated bacterium was classified as Pseudomonas sp. TBD4 based on the close relationship to bacteria belonging to this genus. A bottle study to determine biodegradation rates of individual aromatic compounds showed that the biodegradation was faster in the order of toluene, benzene, styrene, and p-xylene. However, when various mixtures were subjected to TDB4, styrene was degraded at the highest rate, indicating that both toluene and p-xylene could stimulate the degradation of other substrates whereas styrene played as an inhibitor. In addition, the mixed culture and TDB4 were inoculated to the bioactive foam reactor (BFR), and the reactor performance and the corresponding change of microbial community were monitored using the fluorescent in situ hybridization (FISH) method. When an inlet concentration of the VOC mixture increased to greater than 250 ppm, the overall removal efficiency dropped significantly. The FISH measurement demonstrated that the ratio of TDB4 to the total bacteria also decreased to less than 20% along with the decline in removal efficiency in the BFR. As a result, the periodic addition of the pre-grown TDB4 might have been beneficial to achieve a stable performance in the BFR operated over an extended period.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.10
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• pp.1851-1859
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• 2000

Crude oil-degrading bacteria were isolated from the sites contaminated by oil products. The isolates were identified as Acinetobacter sp. A132, Pseudomonas putida A422, Pseudomonas aeruginosa F721, F722, and Xanthomonas maltophilia B823. The results of investigation on the degradability of crude oil indicated that the strain A132 had the highest rate of $6.04g/L{\cdot}day$. Also, the strain A132 and F722 almost degraded each of n-alkane compounds between $nC_{10}$ and $nC_{32}$. The strain A422 degraded benzene and xylene but not n-alkane. The strain B823 grew somewhat in crude oil but did not entirely degrade other substrates used in this study. The results of the GC/FID analysis on the degradability of the mixed n-alkane compounds showed that the strain F722 could degrade 100% of the compounds with $nC_7{\sim}nC_{10}$ and more than 80% of those with $nC_{11}{\sim}nC_{24}$.

• Journal of Soil and Groundwater Environment
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• v.19 no.5
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• pp.9-17
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• 2014

This paper reported the use of real-time polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), and the culture-based method in the intrinsic bioremediation study at a petroleum contaminated site. The study showed that phenol hydroxylase gene was detected in groundwater contaminated with benzene, toluene, ethylbenzene, xylene isomers (BTEX) and methyl tert-butyl ether (MTBE). This indicated that intrinsic bioremediation occurred at the site. DGGE analyses revealed that the petroleum-hydrocarbon plume caused the variation in microbial communities. MTBE degraders including Pseudomonas sp. NKNU01, Bacillus sp. NKNU01, Klebsiella sp. NKNU01, Enterobacter sp. NKNU01, and Enterobacter sp. NKNU02 were isolated from the contaminated groundwater using the cultured-based method. Among these five strains, Enterobacter sp. NKNU02 is the most effective stain at degrading MTBE without the addition of pentane. The MTBE biodegradation experiment indicated that the isolated bacteria were affected by propane. Biodegradation of MTBE was decreased but not totally inhibited in the mixtures of BTEX. Enterobacter sp. NKNU02 degraded about 60% of MTBE in the bioreactor study. Tert-butyl alcohol (TBA), acetic acid, 2-propanol, and propenoic acid were detected using gas chromatography/mass spectrometry during MTBE degraded by the rest cells of Enterobacter sp. NKNU02. The effectiveness of bioremediation of MTBE was assessed for potential field-scale application.