• Journal of Microbiology
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• v.43 no.4
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• pp.325-330
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• 2005

Rhodococcus sp. strain YU6 was isolated from soil for the ability to grow on o-xylene as the sole carbon and energy source. Unlike most other o-xylene-degrading bacteria, YU6 is able to grow on p-xylene. Numerous growth substrate range experiments, in addition to the ring-cleavage enzyme assay data, suggest that YU6 initially metabolizes 0- and p-xylene by direct aromatic ring oxidation. This leads to the formation of dimethylcatechols, which was further degraded largely through meta-cleavage path-way. The gene encoding meta-cleavage dioxygenase enzyme was PCR cloned from genomic YU6 DNA using previously known gene sequence data from the o-xylene-degrading Rhodococcus sp. strain DK17. Subsequent sequencing of the 918-bp PCR product revealed a $98\%$ identity to the gene, encoding meth-ylcatechol 2,3-dioxygenase from DK17. PFGE analysis followed by Southern hybridization with the catechol 2,3-dioxygenase gene demonstrated that the gene is located on an approximately 560-kb megaplasmid, designated pJY J1

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.520-523
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• 2000

Phenol and other phenolic compounds are common constituents of aqueous effluents from processes such as polymeric resin production, oil refining and cokeing plants. Phenol is a both toxic and lethal of fish at relatively low concentrations e.g. 5-25 mg/L and imparts objectionable tastes to drinking water at far lower concentration. Therefore, the treatment of phenol effluent is important. Among the various techniques of phenol wastewater treatment, microbial teratment is a popular process. The breakdown of phenols by microorganisms has recived considerable attention, because of its biochemical interest and its industrial importance in effluent treatment. This research was performed to investigate the dynamics of microbial community, biofilm growth and the comparison of phenol removal efficiency by RBC (Rotating Biological Contactor) using Rhodococcus sp. EL-GT The experiment was carried out at rotating speed of 10ppm and hydraulic retention time of 7 hours. As time passed, phenol removal efficiency was gained highly. The RBC using Rhodococcus sp. EL-GT completely degraded 15 mM.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.92-96
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• 2011

Rhodococcus sp. strain DK17 possesses three megaplasmids (380 kb pDK1, 330 kb pDK2, and 750 kb pDK3). The alkylbenzene-degrading genes (akbABCDEF) are present on pDK2 while the phthalate operons which are duplicated are present on both pDK2 (ophA'B'C'R') and pDK3 (ophABCR). DK17 with an optimal temperature of $30^{\circ}C$ showed no growth at $37^{\circ}C$. When transferred to $30^{\circ}C$, however, the $37^{\circ}C$ culture began to grow immediately, indicating that $37^{\circ}C$ is not lethal but stressful for DK17 growth. In addition, when exposed to $37^{\circ}C$ even for a short time, a part of DK17 cells lost the ability to degrade o-xylene (a model compound of alkylbenzenes). When two hundred colonies were randomly selected for colony PCR for pDK2-specific akbC, ophC', or pDK3-specific ophC, a total of 29 colonies were found to have lost at least one of the three genes. PFGE analysis clearly showed that all the mutants have different megaplasmid profiles from that of DK17 wild type, which are divided into five different cases: Type I (10 mutants, pDK2 loss and acquisition of a new ~700 kb plasmid), Type II (9 mutants, pDK2 loss), Type III (8 mutants, pDK3 loss and acquisition of a new ~400 kb plasmid), Type IV (1 mutant, pDK3 loss), and Type V (1 mutant, pDK2 and pDK3 loss and acquisition of the ~400 kb and ~700 kb plasmids). The above results showing that growth temperature changes can induce physical changes in bacterial genomes suggest that environmental changes in habitats including temperature fluctuations affect significantly the evolution of bacteria.

• Korean Journal of Environmental Agriculture
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• v.40 no.4
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• pp.322-329
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• 2021

BACKGROUND: The fungicide of benomyl, a benzimidazole group, has been commonly used for pesticides against fungal diseases in the world. However, benomyl is rapidly hydrolyzed in the environment after using to control plant diseases and has adverse effects by generating carbendazim, which is toxic to plants, humans, and the environment. METHODS AND RESULTS: In this study, the decomposition effect of carbendazim, a degradation product of benomyl was conducted in pot and field after making a prototype of benomyl-degrading microbial agent (BDMA). We found that the carbendazim-degrading microbial agent (CDMA) (10⁵, 10⁶, and 10⁷ cfu/g soil) decomposed carbendazim by 50% or more in all the treatments, compared to the untreated control in the pot tests after four weeks. The effect of 100% decomposition of carbendazim was observed at 7 days after treatment, when the prototype of BDMA was apllied at 10-folds dilution in the field. The decomposition effect at more than 60% and plant growth promoting effect were observed after 7 days of the treatment, compared with the untreated group in the second field experiment,treated with commercially available concentrations of 500-folds and 1,000-folds. CONCLUSION(S): These results might represent that the BDMA would decompose carbendazim effectively, a decomposition product of the fungicide benomyl, remaining in agricultural area, and it could be utilized practically by using a low dilution rate.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.2
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• pp.117-122
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• 2009

This study was carried out to investigate applicability of Spent Mushroom Media(SMM) as horticultural nursery media. After the mushroom has been harvested, the SMM contains a lot of organic material, different microorganism and high density of mushroom hypha. The pH, phosphate and exchangeable cation concentrations of SMM of Flammulina velutipes were higher than those of any other treatment. The CEC and $NH_4-N$ were the highest in SMM of bottle-cultivated oyster mushroom (Pleurotus ostreatus). Bacteria and fungi showed the highest density in SMM of Flammulina velutipes. Most dominant bacteria were Microbacterium sp., Rhodococcus sp. and Agrobacterium sp. in SMM of Flammulina velutipes and Bacillus sp., Pseudomonas sp., Curtobacterium sp. and Microbacterium sp. in that of Pleurotus eryngii. The SMM contained high density of mushroom hypha that inhibited germination of seed and growth of young seedlings. Therefore, composting process of the SMM is indispensible to decline of vitality of mushroom hypha. The SMM of Flammulina velutipes with 0~30% vermiculite showed high germination rate in red pepper and chinese cabbage seeds. SMM of Pleurotus eryngii with 20% vermiculite showed 100% germination rate in red pepper seeds, but chinese cabbage seeds nearly failed to germinate with 30% vermiculite. The growth of red pepper was increased according to increasing mixture ratio of vermiculite. Accordingly, we concluded that SMM of Flammulina velutipes contained 0~30% of vermiculite can be used to horticultural growth bed for red pepper.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.515-520
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• 2013

Bacterial communities derived from cheonggukjang and raw rice straw collected from a Mireuksan farm and a Heungup cheonggukjang in Gangwon province were investigated using both culture-based method and denaturing gradient gel electrophoresis (DGGE) analysis. Pure cultures, which were isolated from raw rice straw and cheonggukjang and cultured on tryptic soy agar plates (53-76 colonies per plate), were identified by analysis of 16S rRNA sequences. The traditional culture-based method and analysis of PCR-amplified 16S rRNA by DGGE revealed that for samples collected from the Mireuksan farm, Pantoea agglomerans and Bacillus subtilis were the predominant species in the raw rice-straw and cheonggukjang, respectively. For samples collected from the Heungup cheonggukjang, Bacillus amyloliquefaciens was the predominant species in both raw rice straw and cheonggukjang. Other microorganisms, including members of Pantoea, Bacillus, Enterococcus, Enterobacter, Pseudomonas, Rhodococcus, and Acinetobacter, were also present in the raw rice-straw and cheonggukjang, as were bacteria that could not be cultured.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2004.06a
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• pp.269-271
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• 2004

• Journal of Applied Biological Chemistry
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• v.51 no.6
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• pp.307-314
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• 2008

To explore the optimal conditions for the removal of $H_{2}S$ gas by biofiltration, various conditions, including inlet $H_{2}S$ concentration, flow rate, moisture, and cell number, were examined. Heterotrophic bacteria were isolated from the compost of the animal excreta. A strain that effectively removed $H_{2}S$ was selected and identified as Rhodococcus rhodochrous B261 by analysis of its 16S rDNA sequence. A cell number of $10^{7}\;cfu/g^{-}compost$ was sufficient to dominate the microbiota, and an effective removal was observed at $H_{2}S$ gas concentrations below 220 mg/L. The moisture content of 33-38% was suitable for activation of the microbial activity and delaying the desiccation. Higher flow rates resulted in lower removal rates of the $H_{2}S$ gas. Under the conditions of $10^7\;cfu/g^{-}compost$, $H_{2}S$ gas concentrations of 220 mg/L, and moisture content of 33-38%, the inlet $H_{2}S$ gas concentrations of 120 and 400 mg/L were completely removed for 34 and 12 days, respectively. The amount of sulfur removed was $2.99{\times}10^{-9}H_{2}S-S/cell$, which was suggested as the amount of sulfur removed by a single cell. The biofilter consisting of the compost and R. rhodochrous B261 could be suitable for a long-term biofilteration for the removal of $H_{2}S$ and other malodorous compounds.

• Journal of Korean Society on Water Environment
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• v.27 no.3
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• pp.334-341
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• 2011

The free residual chlorine of tap water samples, collected from 266 faucets on the water pipe network in Daegu City, was between 0.1 and 0.79 mg/L. On microorganic tests, general bacteria and the coliform goup were not detected and thus the tap water was turned out to be fit to drink. In particular, samples of which free residual chlorine was 0.1 mg/L and over were cultured in R2A agar media at $25^{\circ}C$ for 7 days, and as a result heterotrophic bacteria were detected in 65.9% of samples; (1). The closer tap water got to the faucet from the stilling basin, the lower residual chlorine concentration became but the more the bacterial count became. And, more bacteria were detected in the R2A agar medium than in the PCA medium. (2). In the case of separated strains, most colonies were reddish or yellowish. 16S rRNA sequence was identified as Methylobacterium sp. and Williamsia sp., and yellow strain was identified as Sphingomonas sp., Sphingobium sp., Novosphingobium sp., Blastomonas sp., Rhodococcus sp. and Microbacterium sp. White strain was identified as Staphylococcus sp. (3). Sterilized tap water in polyethylene bottles was inoculated with separated strain and was left as it was for 2 months. As a result, bio-film was observed in tap water inoculated with Methylobacterium sp. and Sphingomonas sp. It was found that heterotrophic bacteria increased when free residual chlorine was removed from tap water in the water pipe network. Thus, there is a need to determine a base value for heterotrophic bacteria in order to check the cleanliness of tap water in the water pipe network.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.279-284
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• 2018

Membrane biofouling is a critical operational problem that hinders the rapid commercialization of MBRs. Quorum quenching (QQ) has been investigated widely to control membrane biofouling and is accepted as a promising anti-fouling strategy. Various QQ strategies based on bacterial and enzymatic agents have been identified and applied successfully. Whereas, this study aimed to compare indigenously isolated QQ strain i.e., Enterobacter cloaca with well reported Rhodococcus sp. BH4. Both bacterial species were immobilized in polymeric beads and introduced to two different MBRs keeping the overall beads to volume ratio as 1%. Efficiencies of these strains were monitored in terms of prolonging the membrane filtration cycle of MBR, release of extra-cellular polymeric substances, membrane resistivity measurements and mineralization of signal molecules and permeate quality. Indigenous strain (Enterobacter cloaca) was added to $QQ-MBR_E$ while Rhodococcus sp. BH4 was introduced to $QQ-MBR_R$. QQ bacterial embedded beads showed enhanced filtration cycles up to 1.4 and 2.3 times for $QQ-MBR_E$ and $QQ-MBR_R$ respectively as compared to control MBR (C-MBR). Soluble EPS concentration of 52 mg/L was observed in C-MBR while significantly lower EPS concentration of 20 and 10 mg/L was witnessed in $QQ-MBR_E$ and $QQ-MBR_R$, respectively. Therefore, substantial reduction in biofouling showed the effectiveness of indigenous strain.