• Korean Journal of Microbiology
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• v.23 no.1
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• pp.34-42
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• 1985

From Aspergillus nidulans FGSC 168, mutant strains (TCD27, NCN14, and ACN3) were obtained by NTG and 4-NQO treatments. These four mutant strains were unable to grow on medium supplemented with CMC as a sole carbon source and showed lower levels of CMCase activity in comparison with FGSC168. Some characteristics of these four mutant strains in CMCase production were examined. It was appeared that the permeases for CMCase inducer in all the four mutants were not affected. Two mutants, TCD27 and NCN2, might have some defects in regulatory gene for CMCase production. Analyses of enzyme components of CMCase showed that ACN14 might by defective in structural gene for CMCase.

• Journal of the Korean Society of Tobacco Science
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• v.20 no.1
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• pp.40-49
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• 1998

Protoplasts were isolated from mesophyll of tobacco(Nicotiana glauca) transformed with kanamycin-resistant gene (NPT II gene) and potato hairy root callus containing Ri plasmid of Agrobacterium rhiEogenes, and protoplasm fusion was made between the isolated protoplasts. The transgenic tobacco leaf tissue could grow on the media containing high concentrations of kanamycin, but not on the phytohormone-free media. On the other hand, the potato hairy root calli could be cultured on the phytohormone-free media but not on media containing more than 40 ㎍/ml kanamycin. In these conditions, the viability of both protoplasts were above 90%, These selection markers were used for the selection of protoplasts fused between the two, i.e. protoplast fusion was detected using selection media containing 100㎍/ml kanamycin and with no phytohormone. The mixture of 1.0% cellulase, 0.3% macerozyme, and 0.7M mannitol was best for the maximum protoplast production for tobacco, and that of 2.0% cellulase, 2.0% macerozyme, 1.0% dricelase, and 0.5M mannitol for potato. Both tobacco mesophyll and potato callus protoplasts were fused by using PEG solution on the selectable medium. Cell walls were regenerated after 5 days in this medium, and colonies were alive until 4 weeks after cultural, but died after 6 weeks.

• Microbiology and Biotechnology Letters
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• v.31 no.1
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• pp.18-24
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• 2003

For researching nitrogen-fixing bacteria associated with gramineous crops, we collected growing roots of rices, wheats, oats, barleys, ryes, and maizes at 19 sites of southern Korean peninsula. Endophytes and free living bacteria were isolated from those crop roots. Sixty-three isolates were classified on the basis of different morphology, size, color, host of colony, and the 16S rDNAs sequence. The analyses of PCR amplification for nifH gene and nitrogenase activity assay, revealed that all isolates contained nitrogen-fixing abilities. In addition, most of them have cellulase activity which is one of the common features of endophytic bacteria from plant.

• Microbiology and Biotechnology Letters
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• v.21 no.2
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• pp.113-118
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• 1993

Fro the purpose of producing glouse from cellobiose or oligo saccharide and obtaining genetic information of beta-1,4-glucosidase gene, alpha beta-1,4-glucosidase gene of Pseudomonas sp. LBC505, potent cellulase complex and xylanase producing strain, was cloned in Esherichia coli and Bacillus subtilis into pUC19 and pBD64, respectively. Recombinant plasmid pGL1 contained 1.2kb EcoRI fragment was isolated from transformants forming blue color around colony on LB agar plate containing 20 ng/ml of 5-bromo-4-chloro-3-indolyl-beta-D-glucopyranoside(X-glu) and ampicillin.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.10a
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• pp.157-159
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• 2003

We have cloned and sequenced the cDNA coding fur a cellulase from the mulberry longicorn beetle, Apriona germari, with the polymerase chain reaction. And then we have constructed the recombinant plasmid vector for Bombyx mori transfomation experiment. (omitted)

• Journal of Microbiology and Biotechnology
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• v.27 no.3
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• pp.514-523
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• 2017

Carbon catabolite repression is a crucial regulation mechanism in microorganisms, but its characteristic in Rhizopus is still unclear. We extracted a carbon regulation gene, cre, that encoded a carbon catabolite repressor protein (CRE) from Rhizopus stolonifer TP-02, and studied the regulation of CRE by real-time qPCR. CRE responded to glucose in a certain range, where it could significantly regulate part of the cellulase genes (eg, bg, and cbh2) without cbh1. In the comparison of the response of cre and four cellulase genes to carboxymethylcellulose sodium and a simple carbon source (lactose), the effect of CRE was only related to the concentration of reducing sugars. By regulating the reducing sugars to range from 0.4% to 0.6%, a glucose-containing medium with lactose as the inducer could effectively induce cellulases without the repression of CRE. This regulation method could potentially reduce the cost of enzymes produced in industries and provide a possible solution to achieve the largescale synthesis of cellulases.

• Proceedings of the Korean Society of Life Science Conference
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• 2007.10a
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• pp.113.2-113.2
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• 2007

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• The Plant Pathology Journal
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• v.35 no.2
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• pp.91-99
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• 2019

Mitogen-activated protein kinase (MAPK) cascades in fungi are ubiquitously conserved signaling pathways that regulate stress responses, vegetative growth, pathogenicity, and many other developmental processes. Previously, we reported that the AbSte7 gene, which encodes a mitogen-activated protein kinase kinase (MAPKK) in Alternaria brassicicola, plays a central role in pathogenicity against host cabbage plants. In this research, we further characterized the role of AbSte7 in the pathogenicity of this fungus using ${\Delta}AbSte7$ mutants. Disruption of the AbSte7 gene of A. brassicicola reduced accumulation of metabolites toxic to the host plant in liquid culture media. The ${\Delta}AbSte7$ mutants could not efficiently detoxify cruciferous phytoalexin brassinin, possibly due to reduced expression of the brassinin hydrolase gene involved in detoxifying brassinin. Disruption of the AbSte7 gene also severely impaired fungal detoxification of reactive oxygen species. AbSte7 gene disruption reduced the enzymatic activity of cell walldegrading enzymes, including cellulase, ${\beta}$-glucosidase, pectin methylesterase, polymethyl-galacturonase, and polygalacturonic acid transeliminase, during host plant infection. Altogether, the data strongly suggest the MAPKK gene AbSte7 plays a pivotal role in A. brassicicola during host infection by regulating multiple steps, and thus increasing pathogenicity and inhibiting host defenses.

• Microbiology and Biotechnology Letters
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• v.50 no.2
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• pp.245-254
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• 2022

Cellulases are a group of biocatalyst enzymes that are capable of degrading cellulosic biomass present in the natural environment and produced by a large number of microorganisms, including bacteria and fungi, etc. In the current study, we isolated, screened and characterized cellulase-producing bacteria from soil. Three cellulose-degrading species were isolated based on clear zone using Congo red stain on carboxymethyl cellulose (CMC) agar plates. These bacterial isolates, named as HB2, HS5 and HS9, were subsequently characterized by morphological and biochemical tests as well as 16S rRNA gene sequencing. Based on 16S rRNA analysis, the bacterial isolates were identified as Bacillus cerus, Bacillus subtilis and Bacillus stratosphericus. Moreover, for maximum cellulase production, different growth parameters were optimized. Maximum optical density for growth was also noted at pH 7.0 for 48 h for all three isolates. Optical density was high for all three isolates using meat extract as a nitrogen source for 48 h. The pH profile of all three strains was quite similar but the maximum enzyme activity was observed at pH 7.0. Maximum cellulase production by all three bacterial isolates was noted when using lactose as a carbon rather than nitrogen and peptone. Further studies are needed for identification of new isolates in this region having maximum cellulolytic activity. Our findings indicate that this enzyme has various potential industrial applications.

• The Plant Pathology Journal
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• v.29 no.4
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• pp.364-373
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• 2013

It has been known that most regulation of pathogenicity factor (rpf ) genes in xanthomonads regulates virulence in response to the diffusible signal factor, DSF. Although many rpf genes have been functionally characterized, the function of rpfE is still unknown. We cloned the rpfE gene from a Xanthomonas oryzae pv. oryzae (Xoo) Korean race KACC10859 and generated mutant strains to elucidate the role of RpfE with respect to the rpf system. Through experiments using the rpfE-deficient mutant strain, we found that mutation in rpfE gene in Xoo reduced virulence, swarm motility, and production of virulence factors such as cellulase and extracellular polysaccharide. Disease progress by the rpfE-deficient mutant strain was significantly slowed compared to disease progress by the wild type and the number of the rpfE-deficient mutant strain was lower than that of the wild type in the early phase of infection in the inoculated rice leaf. The rpfE mutant strain was unable to utilize sucrose or xylose as carbon sources efficiently in culture. The mutation in rpfE, however, did not affect DSF synthesis. Our results suggest that the rpfE gene regulates the virulence of Xoo under different nutrient conditions without change of DSF production.