• 대한임상검사과학회지
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• 제52권3호
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• pp.221-228
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• 2020

Ochrobactrum anthropi는 oxidase를 생산하는 비발효산소성 그람음성 막대균으로 외관이 비슷하고 oxidase가 양성인 비발효 세균과 혼합배양 시 구분이 힘들고 생화학적 동정 장비로는 정확한 동정에 한계가 있다. 따라서 본 연구에서는 생화학적 검사 방법으로 동정이 힘든 세균동정의 Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Platform (MALDI-TOF) 법의 유용성을 제시하고자 하였다. MicroScan을 이용해 검사했던 O. anthropi 5례를 분석한 결과, 최종보고까지 6.2일이 소요되었으며 E. coli의 3.0일에 비해 3.5일이 더 소요되었다. 5번 환자 고름 검체는 Achromobater xylosoxidans와 혼합감염으로 여러 번의 계대 배양과 재검사로 인해 11.3일이 소요되었는데, MALDI-TOF법으로 검사한 경우 한 번에 동정되었다. 4명의 환자는 기저질환이 있는 60세 이상이었고 기회감염과 원내감염의 가능성을 배제할 수 없었으며, 그 중 92일 만에 채취된 검체는 imipenem과 meropenem에 내성이었다. 따라서 O. anthropi처럼 동정이 까다로운 세균은 신속하고 적절한 환자 치료를 위해 MALDI-TOF법을 이용한 검사가 매우 유용할 것으로 사료된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권3호
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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 Microbiology and Biotechnology
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• 제16권2호
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• pp.232-239
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• 2006

The microbial activity and bacterial community structure of activated sludge reactors, which treated free cyanide (FC), zinc-complexed cyanide (ZC), or nickel-complexed cyanide (NC), were studied. The three reactors (designated as re-FC, re-ZC, and re-NC) were operated for 50 days with a stepwise decrease of hydraulic retention time. In the re-FC and re-ZC reactors, FC or ZC was almost completely removed, whereas approximately 80-87% of NC was removed in re-NC. This result might be attributed to the high toxicity of nickel released after degradation of NC. In the batch test, the sludges taken from re-FC and re-ZC completely degraded FC, ZC, and NC, whereas the sludge from re-NC degraded only NC. Although re-FC and re-ZC showed similar properties in regard to cyanide degradation, denaturing gradient gel electrophoresis (DGGE) analysis of the 16S rRNA gene of the bacterial communities in the three reactors showed that bacterial community was specifically acclimated to each reactor. We found several bacterial sequences in DGGE bands that showed high similarity to known cyanide-degrading bacteria such as Klebsiella spp., Acidovorax spp., and Achromobacter xylosoxidans. Flocforming microorganism might also be one of the major microorganisms, since many sequences related to Zoogloea, Microbacterium, and phylum TM7 were detected in all the reactors.

• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.114-120
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• 2002

A 1,989-bp genomic region encoding nickel resistance genes was isolated from Legionella pneumophila, a pathogen for legionellosis. From a sequencing and computer analysis, the region was found to harbor two structural genes, a nreB-like protein gene (1,149 bp) and a nreA-like protein gene (270 bp), in a row. Both genes exhibited a significant degree of similarity to the corresponding genes from Synechocystis sp. PCC6803 ($54\%$ amino acid sequence identity) and Achromobacter xylosoxidans 31A ($76\%$). The gene was successfully expressed in E. coli MG1655 and conferred a nickel resistance of up to 5 mM in an LB medium and 3 mM in a TMS medium including gluconate as the sole carbon source. E. coli harboring the nickel resistance gene also exhibited a substantial resistance to cobalt, yet no resistance to cadmium or zinc. Since the extracellular concentration of nickel remained constant during the whole period of cultivation, it was confirmed that the nickel resistance was provided by an efflux system like the $Ni^2＋$permease (nrsD) of Synechocystis sp. strain PCC6803. Since polyphosphate (poly-P) is known as a global regulator for gene expression as well as a potential virulence factor in E. coli, the nickel resistance of a ppk mutant of E. coli MG 1655 harboring the nickel resistance gene from L. pneumophila was compared with that of its parental strain. The nickel resistance was significantly attenuated by ppk inactivation, which was more pronounced in an LB medium than in a TMS medium.