• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.81-88
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• 2007

The sprC gene encodes Streptomyces griseus protease C (SGPC), a bacterial chymotrypsin-like serine protease. Because the published data on sprC was not complete, we cloned and analyzed a new DNA fragment spanning downstream to upstream of the sprC gene from S. griseus IFO13350. The cloned 2.3-kb DNA fragment was placed on a high-copy number plasmid and introduced into Streptomyces lividans TK24. Chymotrypsin activity of the transformant was 8.5 times higher than that of the control after 3 days of cultivation and stably maintained until 9 days of cultivation, which dearly indicated that the cloned 2.3-kb fragment contained the entire sprC gene with its own promoter. When the same construct was introduced in the S. griseus IFO13350 (wild strain) and its two mutant strains in the A-factor regulatory cascade, ${\Delta}adpA$ and HO1, the chymotrypsin activity increased fivefold only in the ${\Delta}adpA$ strain. Transcriptional analysis based on RT-PCR revealed that the sprC gene is normally transcribed in both strains; however, earlier transcription was observed in the wild strain compared with the ${\Delta}adpA$ strain. A gel mobility shift assay showed that the AdpA protein did not bind to the promoter region of sprC. All these data clearly indicate that the expression of sprC is not dependent on the AdpA protein, but is distinctly regulated from other chymotrypsin genes composing an AdpA regulon. Earlier morphological differentiation was observed in S. lividans TK24, and S. griseus IFO13350 and HO1, transformed with the expression vector. The transformant of S. griseus ${\Delta}adpA$ formed markedly larger colonies. Antisense repression of sprC resulted in severe decrease of chymotrypsin activity, down to one-third of the control, and delayed morphological differentiation. All these data suggest that SGPC is related to normal morphogenesis in S. griseus.

• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.374-378
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• 2011

To find alternative genetic resources for D-serine dehydratase (E.C. 4.3.1.18, dsdA) mediating the deamination of D-serine into pyruvate, metagenomic libraries were screened. The chromosomal dsdA gene of a wild-type Escherichia coli W3110 strain was disrupted by inserting the tetracycline resistance gene (tet), using double-crossover, for use as a screening host. The W3110 dsdA::tet strain was not able to grow in a medium containing D-serine as a sole carbon source, whereas wild-type W3110 and the complement W3110 dsdA::tet strain containing a dsdA-expression plasmid were able to grow. After introducing metagenome libraries into the screening host, a strain containing a 40-kb DNA fragment obtained from the metagenomic souce derived from a compost was selected based on its capability to grow on the agar plate containing D-serine as a sole carbon source. For identification of the genetic resource responsible for the D-serine degrading capability, transposon-${\mu}$ was randomly inserted into the 40-kb metagenome. Two strains that had lost their D-serine degrading ability were negatively selected, and the two 6-kb contigs responsible for the D-serine degrading capability were sequenced and deposited (GenBank code: HQ829474.1 and HQ829475.1). Therefore, new alternative genetic resources for D-serine dehydratase was found from the metagenomic resource, and the corresponding ORFs are discussed.

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.563-570
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• 2016

Two Streptomyces griseus strains, a wild-type strain and an A-factor-dependent transcriptional activator mutant strain harboring multiple copies of a gene, dasA, that encodes a substrate-binding protein of the ATP-binding cassette transporter, showed severe ectopic sporulation of young substrate hyphae in response to glucose. The effect of dasA overexpression on the ectopic sporulation of Streptomyces strains was evaluated by comparing the transcriptomes of the strain harboring multiple copies of dasA and a strain harboring empty vector. By DNA microarray, 4 genes (SGR794, SGR2469, SGR3656, and SGR3657) and 3 clusters (SGR795-797, SGR2377-2378, and SGR6997-6998) were differentially expressed by more than 2-fold in S. griseus strains harboring dasA. The DNA microarray result was validated by low-resolution S1 nuclease mapping.

• 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.

• The Korean Journal of Mycology
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• v.22 no.4
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• pp.332-337
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• 1994

Under standard condition (Han, et al., 1990: glucose 1%-nitrate 0.1% minimal medium, 30 ml in 9 cm plate, $10^6$ cells of inoculum per plate), wild type of Aspergillus nidulans developed both sexual and asexual organs in ballance, while velA1 mutant developed asexual ones preferentially. Increase of glucose concentration did not significantly affect the asexual sporulation. However, development of sexual organs were largely affected. It was greatly enhanced when favorable nitrogen source, for example, casein hydrolysate was added, which is contrary to the case of Neurospora or Saccharomyces where limitation of N source induces sexual development. On most of moderate C sources asexual development in $velA^+$ strain was largely inhibited except acetate on which only asexual spores were produced, while that in velA1 mutant strain was not affected. Lactose promoted the sexual development even in velA1 mutant indicating that lactose itself or its metabolic intermediate may induce sexual development independent of allelic state of velA gene. On other moderate favorable C sources, glycerol, galactose and ethanol, asexual development was largely inhibited in $velA^+$ strain but not in velA1 mutant strain. Sexual organs were, however, never produced on acetate. These results suggested that asexual development of wild type is largely dependent on C sources and the velA gene is involved in the repression of asexual development in not-enough-grown (non-competent) thalli resulting in preferential progression of sexual development.

• Pediatric Infection and Vaccine
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• v.29 no.2
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• pp.110-117
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• 2022

Herpes zoster (HZ) has been reported in immunocompetent children who received the varicella vaccine. In vaccinated children, HZ can be caused by vaccine-strain or by wild-type varicella-zoster virus (VZV). Like wild-type VZV, varicella vaccine virus can establish latency and reactivate as HZ. We report two cases of HZ in otherwise healthy 16- and 14-month-old boys who received varicella vaccine at 12 months of age. They presented with a vesicular rash on their upper extremities three to four months after varicella vaccination. In one case, a swab was obtained by abrading skin vesicles and VZV was detected in skin specimens by polymerase chain reaction. The VZV open-reading frame 62 was sequenced and single nucleotide polymorphism analysis confirmed that the virus from skin specimen was vaccine-strain. This is the first HZ case following varicella vaccination confirmed to be caused by vaccine-strain VZV in the immunocompetent children in Korea. Pediatricians should be aware of the potential for varicella vaccine virus reactivation in vaccinated young children.

• Applied Biological Chemistry
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• v.51 no.1
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• pp.24-37
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• 2008

Yeast with excellent ferment ability was isolated and selected from wild grape to manufacture wild grape wine. Wild grape wine by SMR-3 isolated from wild grape was better than other strains in quality, such as high alcohol content and low acidity, residual sugar, organic acid and fusel oil content. Fermentation condition was optimized to manufacture wild grape wine with response surface methodology using isolated SMR-3 as an alcohol fermentation strain. As a result of culture conditions, 10.61% of alcohol content was expected under the conditions of $21.91^{\circ}C$ fermenting temperature, $21.48^{\circ}brix$ of initial sugar content, and 14.65 day of fermentation time. Residual sugar content showed the lowest value at $24.48^{\circ}C$ fermentation temperature, $12.78^{\circ}brix$ of initial sugar content, and 9.02 day fermentation time. The highest level of sensory evaluation was found at $20.23^{\circ}C$ fermentation temperature, $25.30^{\circ}brix$ of initial sugar content, and 5.94 day fermentation time. Ethyl alcohol was the main alcohol component in wild grape wine and fusel oil in wild grape wine was hardly detected; thus, the quality of wild grape wine was considered excellent. The optimal fermentation conditions of wild grape wine was superimposed by deriving a regression equation for alcohol content, fusel oil, ethyl alcohol content, and overall palatability for each variable of wild grape wine. Hence, the optimal fermentation conditions are estimated to be: fermentation temperature $24{\sim}28^{\circ}C$, initial sugar content $20{\sim}24^{\circ}brix$, and fermenting time $12{\sim}14$ days.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.333-337
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• 2011

A new and a unique Brachionus rotifer was found in Hwajinpo coastal lagoon in Gangwon Province, South Korea. This Brachionus certainly originated from the wild rather than from aquaculture stations because Hwajinpo coastal lagoon has been under rigorous control as a military protected area and therefore could not have been contaminated by aquaculture stations. The new strain was identified as Brachionus rotundiformis based upon its morphological characteristics. The parthenogenetic female of this new rotifer strain typically shows characters similar to those of B. rotundiformis, such as the pot shape of the body, rounded dorsal plate compared with flattened ventral plate, elliptical mictic egg, four frontal spines, six pointed occipital spines, non-nodal foot, two toes, trophi typical of the Brachionus genus with five uncus plates resembling comb teeth, one wide symmetrical manubrium and ramus, and no stiffened spine as is seen in freshwater Brachionus rotifers. Moreover, its lorica was rather small in size compared with other common rotifer strains that serve as live-food organisms (Guam, Thai, and Bali strains). This new and unique Korean brackish rotifer, a B. rotundiformis strain, was therefore named the National Fisheries Research and Development Institute (NFRDI) $N^{\circ}1$ rotifer strain.

• Mycobiology
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• v.51 no.3
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• pp.169-177
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• 2023

To further explore the molecular mechanism of triterpenoid biosynthesis and acquire high-value strain of Sanghuangporus baumii, the Agrobacterium tumefaciens-mediated transformation (ATMT) system was studied. The key triterpenoid biosynthesis-associated gene isopentenyl diphosphate isomerase (IDI) was transformed into S. baumii by ATMT system. Then, the qRT-PCR technique was used to analyze gene transcript level, and the widely targeted metabolomics was used to investigate individual triterpenoid content. Total triterpenoid content and anti-oxidant activity were determined by spectrophotometer. In this study, we for the first time established an efficient ATMT system and transferred the IDI gene into S. baumii. Relative to the wild-type (WT) strain, the IDI-transformant (IT) strain showed significantly higher transcript levels of IDI and total triterpenoid content. We then investigated individual triterpenoids in S. baumii, which led to the identification of 10 distinct triterpenoids. The contents of individual triterpenoids produced by the IT2 strain were 1.76-10.03 times higher than those produced by the WT strain. The triterpenoid production showed a significant positive correlation with the IDI gene expression. Besides, IT2 strain showed better anti-oxidant activity. The findings provide valuable information about the biosynthetic pathway of triterpenoids and provide a strategy for cultivating high-value S. baumii strains.

• Korean Journal of Veterinary Service
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• v.30 no.3
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• pp.291-304
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• 2007

Mutants of an obligate aerobic bacterium, Vitreoscilla, that have deficiency in heat-labile catalase-peroxidase hydroperoxidase I (HPI) were created by EMS treatment. The catalase-peroxidase HPI-deficient mutant showed substantially lower peroxidase activity in exponential and mid-stationary phase compared with the wild type strain. In late stationary phase, the mutant exhibited no peroxidase activity. Peroxidase deficiency in the mutant was revealed by polyacrylamide gels stained for peroxidase activity. Characteristically, catalase levels in the mutant increased about 14- and 8-fold during growth in the exponential and stationary phases, respectively, compared to those in the wild type, suggesting a compensatory effect for protection from $H_2O_2$ toxicity. The mutant showed differences in physiology from the wild type: retardation in growth rate and decrease in oxygen consumption. Both the wild type and the catalase-peroxidase HPI-deficient mutant of Vitreoscilla had lower growth rates in media containing increasing $H_2O_2$ concentrations. However, the mutant exhibited an additionally decreased growth rate after 6 to 8 h of growth compared to the wild type. The wild type was resistent up to 20 mM $H_2O_2$, whereas the mutant was very sensitive to high concentrations of exogenous $H_2O_2$. Although elevated catalase levels would provide protection of the bacteria from the deleterious effect of $H_2O_2$, it did not appear to be complete. Cell-free extracts of the mutant showed decreased NADH oxidation rates and higher accumulation of $H_2O_2$ during this oxidation. These results may account for the impaired growth and earlier onset of death phase by the catalase-peroxidase HPI-deficient mutant of Vitreoscilla.