• 한국미생물·생명공학회지
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• 제22권4호
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• pp.340-346
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• 1994

Six bacterial strains capable to grow on medium containing cholesterol as sole carbon source were isolated from soil, pork fat and cheese. Three of them were tentatively identified as Rhodococcus species, Rhodococcus sp. CD-1, R. sp. CD-2, and R. sp. CD-3. All the isolates showed a varying amount of cholest-4-en-3-one as the degradation product, and three strains of Rhodococcus spp. showed rapid degradation of cholesterol. Radioisotopic studies revealed that cholesterol was degraded to non-sterol hydrophilic compounds via cholest-4-en-3-one, and presumably to C0$_{2}$- These strains showed two distinct patterns in further degradation of cholest-4-en-3-one. By one group, R. sp. CD-1 and R. sp. CD-3, cholest-4-en-3-one was rapidly converted to non-sterol inter- mediates without significant accumulation of sterol derivatives in the culture broth. In contrast, by another group, R. sp. CD-2, the substantial amount of cholest-4-en-3-one was accumulated indica- ting a lower conversion of the compound to the next metabolites.

• 한국토양환경학회지
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• 제1권2호
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• pp.35-42
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• 1996

포항근해의 정점을 대상으로 1995년 4월부터 1996년 1월까지 3개월 간격으로 종속영양세균과 원유분해세균의 분포를 조사하였다. 또한, 분리된 원유분해세균의 단일 및 혼합배양을 통하여 원유분해능도 조사하였다. 종속영양세균의 분포는 4.1 $\times$ $10^4$ - 1.2 $\times$ $10^5$ CFU/$m\ell$ 이었으며 종속영양세균에 대한 원유분해세균의 분포비는 0.05 -0.54%로서 지금까지 보필된 타지역보다 낮은 수치였다. 이 결과에서 포항근해의 원유분해세균의 분포는 육지로부터 유입되는 석유계 탄화수소에 의하여 크게 영향을 받는것으로 사료된다. 원유분해능이 우수한 26 균주를 분리.동정한 결과 Acinetobacter spp., Bacillus spp., Citrobacter spp., Micrococcus spp., Moraxella spp., Rhodococcus spp., 그리고 Berratia spp. 등의 7개 속이 나타났고, 장내세균의 출현은 해수내 오수의 유입을 반영하고 있었다. 또한 Bacillus 속 균주가 포항근해의 원유분해세균의 우점종으로 밝혀졌다. 원유분해세균을 이용한 플라스크 배양에서 원유분해는 혼합배양에 의해 증가하였다.

• Journal of Microbiology and Biotechnology
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• 제30권6호
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• pp.937-945
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• 2020

N-acyl-homoserine lactone (AHL)-mediated quorum sensing (QS) plays a major role in development of biofilms, which contribute to rise in infections and biofouling in water-related industries. Interference in QS, called quorum quenching (QQ), has recieved a lot of attention in recent years. Rhodococcus spp. are known to have prominent quorum quenching activity and in previous reports it was suggested that this genus possesses multiple QQ enzymes, but only one gene, qsdA, which encodes an AHL-lactonase belonging to phosphotriesterase family, has been identified. Therefore, we conducted a whole genome sequencing and analysis of Rhodococcus sp. BH4 isolated from a wastewater treatment plant. The sequencing revealed another gene encoding a QQ enzyme (named jydB) that exhibited a high AHL degrading activity. This QQ enzyme had a 46% amino acid sequence similarity with the AHL-lactonase (AidH) of Ochrobactrum sp. T63. HPLC analysis and AHL restoration experiments by acidification revealed that the jydB gene encodes an AHL-lactonase which shares the known characteristics of the α/β hydrolase family. Purified recombinant JydB demonstrated a high hydrolytic activity against various AHLs. Kinetic analysis of JydB revealed a high catalytic efficiency (k_cat/K_M) against C4-HSL and 3-oxo-C6 HSL, ranging from 1.88 x 10⁶ to 1.45 x 10⁶ M^-1 s^-1, with distinctly low K_M values (0.16-0.24 mM). This study affirms that the AHL degrading activity and biofilm inhibition ability of Rhodococcus sp. BH4 may be due to the presence of multiple quorum quenching enzymes, including two types of AHL-lactonases, in addition to AHL-acylase and oxidoreductase, for which the genes have yet to be described.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2001년도 추계학술대회
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• pp.157-163
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• 2001

Mycolic acid-containing gram-positive bacteria, so called nocardioform actinomycetes, have become a great interest to environmental microbiologists due to their metabolic versatility, multidegradative capacity and potential for bioremediation of priority pollutants. For example, Rhodococcus rhodochrous N75 was able to metabolize 4-methy1catechol via a modified $\beta$-ketoadipate pathway whereby 4-methylmuconolactone methyl isomerase catalyzes the conversion of 4-methylmuconolactone to 3-methylmuconolactone in order to circumvent the accumulation of the 'dead-end' metabolite, 4-methylmuconolactone. R. rhodochrous N75 has also shown the ability to transform a range of alkyl-substituted catechols to the corresponding muconolactones. A novel 3-methylmuconolactone-CoAsynthetase was found to be involved in the degradation of 3-methylmuconolactone, which is not mediated in a manner analogous to the classical $\beta$-ketoadipate pathway but activated by the addition of CoA prior to hydrolysis of lactone ring, suggesting that the degradative pathway for methylaromatic compounds by gram-positive bacteria diverges from that of proteobacteria. Mycobacterium sp. Strain PYR-l isolated from oil-contaminated soil was capable of mineralizing various polyaromatic hydrocarbons (PAHs), such as naphthalene, phenanthrene, pyrene, fluoranthrene, 1-nitropyrene, and 6-nitrochrysene. The pathways for degradation of PAHs by this organism have been elucidated through the isolation and characterization of chemical intermediates. 2-D gel electrophoresis of PAH-induced proteins enabled the cloning of the dioxygenase system containing a dehydrogenase, the dioxygenase small ($\beta$)-subunit, and the dioxygenase large ($\alpha$)-subunit. Phylogenetic analysis showed that the large a subunit did not cluster with most of the known sequences except for three newly described a subunits of dioxygenases from Rhodococcus spp. and Nocardioides spp. 2-D gel analysis also showed that catalase-peroxidase, which was induced with pyrene, plays a role in the PAH metabolism. The survival and performance of these bacteria raised the possibility that they can be excellent candidates for bioremediation purposes.

• 대한수의학회지
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• 제39권3호
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• pp.523-530
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• 1999

Sal enteritidis thin fimbriae, SEF14, were found to be restricted to the predominantly poultry-associated members of the Salmonella serogroup D1 that are considered as the important pathogens in poultry industry. SefA together with sefB and sefC encode the proteins involved in SEF14 biosynthesis. In order to develop the rapid and specific detection methods for Salmonella serogroup D1, a PCR technique for the amplification of sefA gene was established, and its specificity and sensitivity were investigated with various microorganisms. The bacterial genomic DNA was extracted by colony-picking and rapid boiled-lysate technique. In comparison of Sef I and Sef II primers used in the PCR, Sef I primer for sefA gene of 513bp showed higher specificity than that of Sef II. The established PCR was as sensitive as to detect 1pg of Sal enteritidis DNA. When 73 strains in 28 genera including the reference strains and the field isolates of various Salmonella serotypes, Bacillus subtilis, Bordetella bronchisepdca, E coli, Listeria spp., Micrococcus luteus, Rhodococcus equi, Staphylococcus spp., Streptococcus spp., Vibrio parahemolyticus, Yersinia spp. were studied, the established PCR yielded specifically positive results with only Salmonella serogroup D1. The results suggested that the PCR for sefA gene could be a potential candidate among the specific detection methods for Salmonella serogroup D1.