• Journal of Microbiology and Biotechnology
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• v.20 no.12
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• pp.1696-1701
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• 2010

The ${\alpha}$-amylases activity was improved by random mutagenesis and screening. A region comprising residues from the position 34-281 was randomly mutated in B. licheniformis ${\alpha}$-amylase (AmyL), and the library with mutations ranging from low, medium, and high frequencies was generated. The library was screened using an effective liquid-phase screening method to isolate mutants with an altered pH profile. The sequencing of improved variants indicated 2-5 amino acid changes. Among them, mutant TP8H5 showed an altered pH profile as compared with that of wild type. The sequencing of variant TP8H5 indicated 2 amino acid changes, Ile157Ser and Trp193Arg, which were located in the solvent accessible flexible loop region in domain B.

• Preventive Nutrition and Food Science
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• v.13 no.3
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• pp.190-195
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• 2008

The $\alpha$-amylase gene, amyL, from Bacillus licheniformis was expressed in Lactobacillus brevis 2.14 and Escherichia coli $DH5{\alpha}$ using two different shuttle vectors, pCW4 and pSJE. E. coli transformants (TFs) harboring either $pCW4T{\alpha}$ or $pSJET{\alpha}$ produced active $\alpha$-amylase but L. brevis TFs did not, as determined by enzyme assays and zymography. But amyL transcripts were synthesized in L. brevis TFs. In terms of plasmid stability, pSJE, a theta-type replicon, was more stable than pCW4, an RCR (rolling circle replication) plasmid, in L. brevis without antibiotic selection.

• Bulletin of the Korean Chemical Society
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• v.15 no.10
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• pp.832-835
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• 1994

The ${alpha}$-amylase gene of Bacillus licheniformis has been cloned and two mutant ${alpha}$-amylase genes of which histidine 235 was changed to glutamine (H235Q) and aspartic acid 328 to glutamic acid (D328E) have been produced by site-directed mutagenesis. The kinetic parameters, optimum pH and thermostability of wild type(WT) and these two mutant amylases expressed in E. coli MC1061 have been compared after purification. The $K_m$ values of WT, H235Q and D328E ${alpha}$-amylases were 0.22%, 0.73%, and 0.80% respectively, when using starch as the substrate. The $V_max$ values of wild type ${alpha}$ -amylase and mutant ${alpha}$-amylases were 0.6-0.7%/minute, and did not show any significant differences among them. The optimum pH of D328E ${alpha}$-amylase was shifted to more acidic pH. Also, the thermostability of H235Q ${alpha}$-amylase was increased compared to the wild type ${alpha}$-amylase.

• Journal of Microbiology and Biotechnology
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• v.29 no.2
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• pp.268-273
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• 2019

The specificity of a Bacillus licheniformis uridine diphosphate (UDP) glycosyltransferase, YjiC, was increased towards thymidine diphosphate (TDP)-sugar by site-directed mutagenesis. The Arg-282 of YjiC was identified and investigated by substituting with Trp. Conversion rate and kinetic parameters were compared between YjiC and its variants with several acceptor substrates such as 7-hydroxyflavone (7-HF), 4',7-dihydroxyisoflavone, 7,8-dihydroxyflavone and curcumin. Molecular docking of TDP-glucose and 7-HF with YjiC model showed pi-alkyl interaction with Arg-282 and His-14, and pi-pi interaction with $His^{14}$ and thymine ring. YjiC (H14A) variant lost its glucosylation activity with TDP-glucose validating significance of His-14 in binding of TDP-sugars.

• Journal of Microbiology and Biotechnology
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• v.34 no.7
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• pp.1443-1451
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• 2024

Weizmannia coagulans can be used as a starter strain in fermented foods or as a probiotic. However, it is salt-sensitive. Here, W. coagulans genomes were compared with the genomes of strains of Bacillus species (B. licheniformis, B. siamensis, B. subtilis, and B. velezensis) that were isolated from fermented foods and show salt tolerance, to identify the basis for the salt-sensitivity of W. coagulans. Osmoprotectant uptake (Opu) systems transport compatible solutes into cells to help them tolerate osmotic stress. B. siamensis, B. subtilis, and B. velezensis each possess five Opu systems (OpuA, OpuB, OpuC, OpuD, and OpuE); B. licheniformis has all except OpuB. However, W. coagulans only has the OpuC system. Based on these findings, the opuA and opuB operons, and the opuD and opuE genes, were amplified from B. velezensis. Expression of each of these systems, respectively, in W. coagulans increased salt-tolerance. W. coagulans expressing B. velezensis opuA, opuD, or opuE grew in 10.5% NaCl (w/v), whereas wild-type W. coagulans could not grow in 3.5% NaCl. The salt resistance of B. subtilis was also increased by overexpression of B. velezensis opuA, opuB, opuD, or opuE. These results indicate that the salt-susceptibility of W. coagulans arises because it is deficient in Opu systems.

• Journal of Chitin and Chitosan
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• v.23 no.4
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• pp.285-292
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• 2018

In this study, for the purpose of decomposing food waste, the strain was screened from traditional fermented food and soils. The enzyme activity (protease, amylase, cellulase, lipase) experiment was carried out using the paper disc method in 212 strains isolated from 5% NaCl media. Among them, only the strains having enzyme activity of more than 2 (soil) or more than 4 (traditional fermented food) with the halozone of enzyme activity of 15 mm or more were selected first, and microorganism identification through 16S rRNA sequencing was performed. Finally, were identified such as Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus siamensis, Bacillus licheniformis, Bacillus aquimaris, Bacillus megaterium, Bacillus koreensis, Bacillus stratoshericus, Bacillus aryabhattai, Bacillus safensis, Marinobacter hydrocarbonoclasticus. 11 species of mixed strains were confirmed that the culture time was 24 hours, the incubation temperature was $30^{\circ}C$ and the optimum pH was 7.0. In order to confirm the degree of decomposition of standard food wastes (100 g) by treating 11 kinds of mixed strains (25%), solid content of more than $2000{\mu}m$ was determined to be 103 g for the sterilized water group and 18 g for the mixed strains group. And the rest was decomposed to a size of less than $2000{\mu}m$.

• The Plant Pathology Journal
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• v.18 no.1
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• pp.36-42
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• 2002

Resistance of perilla varieties to Botrytis cinerea LVF12 was evaluated, while antagonistic bacteria were selected and tested for their efficacy towards biological control of gray mold rot caused by B. cinerea. Among 11 perilla varieties tested for disease resistance, Milyang variety showed some degree of resistance, while the rest of varieties showed no resistance. Among 250 bacterial isolates collected from perilla loaves and rhizosphere of perilla plants, six isolates showed high levels of inhibitory effect on mycelial growth and conidial germination of B. cinerea in in vitro test. Using the pot test in growth chambers these isolates showed high levels of disease suppression, with Nl isolate showing 95.3% of control value and N4 isolate showing 90.8% of control value. Further test was performed to evaluate the two isolates ability for disease prevention and/or disease therapy, and results showed almost 100% of control vague. Isolates Nl and N4 were identified as Bacillus licheniformis and 5. megatepium, respectively, according to Bergey's manual, API 20E and 50CHB test kit, and Transmission electron microscope.

• Food Science of Animal Resources
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• v.22 no.3
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• pp.267-273
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• 2002

The functional properties of egg shell membrane hydrolysate by Bacillus licheniformis(EESMH) and NaOH-ethanol(AESMH) as a food material were investigated.. The yield of egg shell membrane hydrolysate was about 15% by Bacillus licheniformis, whereas that was 70% by NaOH-ethanol. Histidine content was higher in EESMH (18.69%) than in AESMH (2.56%). Both EESMH and AESMH showed high protein solubility (>95%). Emulsi-fying activity and stability of EESMH were higher than those of AESMH. foaming capacity and stability of AESMH were 2 times higher than those of EESMH in the pH ranges from 2 to 12. The AESMH had antioxidative activity whereas EESMH had not. Therefore, both AESMH and EESMH can be used for industrial food materials from the results of functional properties.

• Applied Biological Chemistry
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• v.49 no.3
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• pp.175-179
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• 2006

This study was carried out to investigate the change of rhizosphere microflora in paddy soils of long-term application of same fertilizer by single cropping. Treatments consisted of no fertilizer, NPK, PK, NK, NP and NPK + compost and the same fertilizer has been applied to the soil of each treatment for thirty five years. Any remarkable difference of the microbial population structure was not detected from the rhizosphere of Hwayeongbyeo and that of Hwasambyeo. However, slight difference of dominant microbial species in the rhizosphere was recognized between different fertilization practice. The bacterial population in the rhizosphere was steadily reduced over time after rice plant setting out, while actinomycetal population was increased over time. The increase of actinomycetal population was the highest in the NPK + compost treatment, suggesting the effect of organic matters in the change of actinomycetal population. As for the aerobic culturable bacterial diversity, Bacillus megaterium, B. mycoides, B. licheniformis and B. subtilis were dominants in genus Bacillus, and Streptomyces spororaveus, S. canus, S. tauricus and S. galbus in genus Streptomyces and genus Micromonospora was another dominant in actinomycetes.

• Applied Biological Chemistry
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• v.7
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• pp.53-58
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• 1966

A study was carried out to investigate the microorganisms and their floral changes during the tobacco fermentation. The results were sumarized as follows. I. The molds in the "tobacco leaves" were isolated and identified as follows; Aspergllus flavus Link, A. restrictus G. Smith, A. nidulans (Eidam) Wint, A. awamori, Oidium sp. Edmundmasonia sp. Spicaria sp. II. The bacteria in the tobacco were isolated and identified as follows; Bacillus subtilis, B. subtilis var aterriums. B. licheniformis, B. cereus, B. Pumilus, B. megaterium, Flavobacterium harrisonii, Aerobacter aerogenes. III. The counts of the microorganisms on leaves taken from bulks of the fermenting leaf tobacco revealed the presence of relatively small number on the initial stage of the fermentation. During the tobacco fermentation the number of molds increase gradually to the maximum until the 14 th. day of the fermenation, followed by showing, the plateau, and the bacteria population revealed the maximum on the 7 th. day, then declined slowly.