Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Diversity and Physiological Properties of Root Endophytic Actinobacteria in Native Herbaceous Plants of Korea: Tae-Ui Kim , Sung-Heun Cho , Ji-Hye Han , Young Min Shin , Hyang Burm Lee , Seung Bum Kim; J. Microbiol. 2012;50(1):50-57. Published online February 27, 2012; DOI: https://doi.org/10.1007/s12275-012-1417-x

Abstract: Endophytic actinobacterial diversity in the native herbaceous plant species of Korea was analyzed using a culturebased approach. Sixty one actinobacterial strains were isolated, and assigned to 15 genera based on 16S rRNA gene analysis. The members of the genus Streptomyces comprised 45.9% of the total isolates, followed by Micromonospora (18.8%), Rhodococcus (6.6%), Microbispora (4.9%), and Micrococcus (4.9%). Other minor constituents included members of Microbacterium, Streptacidiphilus, Arthrobacter, Dietzia, Kitasatospora, Herbiconiux, Mycobacterium, Nocardia, Rathayibacter, and Tsukamurella. Among the isolates, 65.6% exhibited at least one hydrolytic enzyme activity out of four, and 45.9% exhibited antagonistic activity against at least one fungal pathogen out of five, thus demonstrating that endophytic actinobacteria can be an important source of bioactive compounds. Notably, most strains of Streptomyces proved active for both enzymatic and antagonistic activities.

Isolation and Characterization of a Rhodococcus Species Strain Able to Grow on ortho- and para-Xylene: Jung Yeon Jang , Dockyu Kim , Hyun Won Bae , Ki Young Choi , Jong-Chan Chae , Gerben J. Zylstra , Young Min Kim , Eungbin Kim; J. Microbiol. 2005;43(4):325-330.; DOI: https://doi.org/2258 [pii]

Abstract: 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 o- and p-xylene by direct aromatic ring oxidation. This leads to the formation of dimethylcatechols, which was further degraded largely through meta-cleavage pathway. 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 methylcatechol 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 pJYJ1 <br>

Research Support, U.S. Gov't, Non-P.H.S.

Identification of Two-Component Regulatory Genes Involved in o-Xylene Degradation by Rhodococcus sp. Strain DK17: Dockyu Kim , Jong-Chan Chae , Gerben J. Zylstra , Ho-Yong Sohn , Gi-Seok Kwon , Eungbin Kim; J. Microbiol. 2005;43(1):49-53.; DOI: https://doi.org/2138 [pii]

Abstract: Putative genes for a two-component signal transduction system (akbS and akbT) were detected near the alkylbenzene-degrading operon of Rhodococcus sp. DK17. Sequence analysis indicates that AkbS possesses potential ATP-binding and histidine autophosphorylation sites in the N- and C-terminal regions, respectively, and that AkbT has a typical response regulator domain. Mutant analysis combined with RT-PCR experiments further shows that AkbS is required to induce the expression of o-xylene dioxygenase in DK17.

Research Support, Non-U.S. Gov't

Molecular Cloning and Identification of a Novel Oxygenase Gene Specifically Induced during the Growth of Rhodococcus sp. Strain T104 on Limonene: Ki Young Choi , Dockyu Kim , Sung-Cheol Koh , Jae-Seong So , Jong-Sul Kim , Eungbin Kim; J. Microbiol. 2004;42(2):160-162.; DOI: https://doi.org/2027 [pii]

Abstract: Rhodococcus sp. strain T104 is able to utilize both limonene and biphenyl as growth substrates.Furthermore, T104 possesses separate pathways for the degradation of limonene and biphenyl. Previously, we found that a gene(s) involved in limonene degradation was also related to indigo-producing ability. To further corroborate this observation, we have cloned and sequenced a 8,842-bp genomic DNA region with four open reading frames, including one for indole oxygenase, which converts indole to indigo (a blue pigment). The reverse transcription PCR data demonstrated that the identified indole oxygenase gene is specifically induced by limonene, thereby implicating this gene in the degradation of limonene by T104.

Three Separate Pathways for the Initial Oxidation of Limonene, Biphenyl, and Phenol by Rhodococcus sp. Strain T104: Dockyu Kim , Min Jung Park , Sung-Cheol Koh , Jae-Seong So , Eungbin Kim; J. Microbiol. 2002;40(1):86-89.

Abstract: Rhodococcus sp. strain T104, which is able to grow on either biphenyl or limonene, was found to utilize phenol as sole carbon and energy sources. Furthermore, T104 was positively identified to possess three separate pathways for the degradation of limonene, phenol, and biphenyl. The fact that biphenyl and limonene induced almost the same amount of catechol 1,2-dioxygenase activity indicates that limonene can induce both upper and lower pathways for biphenyl degradation by T104.

Plant Terpene-Induced Expression of Multiple Aromatic Ring Hydroxylation Oxygenase Genes in Rhodococcus sp. Strain T104: Byung-Hyuk Kim , Eun-Taex Oh , Jae-Seong So , Yeonghee Ahn , Sung-Cheol Koh; J. Microbiol. 2003;41(4):349-352.

Abstract: Recent studies have shown that some of the PCB (polychlorinated biphenyl)-degraders are able to effectively degrade PCB in the presence of monoterpenes, which act as inducers for the degradation pathway. Rhodococcus sp. T104, an effective PCB degrader, has been shown to induce the degradation pathway by utilizing limonenes, cymenes, carvones, and pinenes as sole carbon sources which can be found in the natural environment. Moreover, the strain T104 proved to possess three separate oxidation pathways of limonene, biphenyl, and phenol. Of these three, the limonene can also induce the biphenyl degradation pathway. In this work, we report the presence of three distinct genes for aromatic oxygenase, which are putatively involved in the degradation of aromatic substrates including biphenyl, limonene, and phenol, through PCR amplification and denaturing gradient gel electrophoresis (DGGE). The genes were differentially expressed and well induced by limonene, cymene, and plant extract A compared to biphenyl and/or glucose. This indicates that substrate specificity must be taken into account when biodegradation of the target compounds are facilitated by the plant natural substrates.

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