• The Korean Journal of Mycology
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• v.15 no.3
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• pp.187-195
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• 1987

Two kinds of heat treatment method for the selective isolation of soil fungi to eliminate the commonest fungi and also to examine the vertical and seasonal distributions of the fungal population were applied to soil samples from two plots around Seoul area. The incubation method at $42^{\circ}C$ and heat treatment at $70^{\circ}C$ were used in this experiment. In the incubation method, the almost all the fungi isolated from two plots were mesophile, while the thermotolerant fungi was Aspergillus fumigatus and thermophilic fungi were Sporotrichum thermophile and Malbranchea pulchella var. sulfrea. The most dominant species isolated by this method was A. fumigatus. Nine genera and fourteen species were isolated from the two plots, and S. thermophile, Talaromyces ucrainicus,Malbranchea pulchella var. sulfrea were new to Korea. From the selection method by heat treatment at $70^{\circ}C$, ten genera and twenty species were isolated. Among these, the most fungi were also mesophile and thermotolerant fungus was A. fumigatus. The most dominant species isolated by this method was T. stipitatus, Talaromyces helicus var. major, Emericella nidulans var. nidulans, Chaetomium subspirale and Neosartorya fisheri var. fisheri were new to Korea. From the two isolation methods, it was found that the total number of soil fungi and frequency of species appeared including dominant ones were the highest at the soils of upper layer while the lowest at the soils of lower layer in its vertical distribution.

• The Korean Journal of Mycology
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• v.32 no.2
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• pp.134-137
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• 2004

This study was carried out to determine the optimum culture conditions for Phellinus spp. known as white rot fungi showing anti-cancer activity. The optimum solid medium for mycelial growth at $25^{\circ}C$ was potato dextrose agar medium and optimum pH range was $6.0{\sim}8.0$, while all species showed reduced or no growth at pH 4.0. Most species showed good growth at $25{\sim}30^{\circ}C$. Out of 10 species of Phellinus examined, P. biscuspidatus was the best growing fungus in the range of pH $6.0{\sim}7.0$ based on mycelial density. Three species such as P. biscuspidatus, P. johnsonianus and P. lloydii could be grouped in mesophile fungi, showing $30{\sim}35^{\circ}C$ optimum temperature.

• Journal of Microbiology and Biotechnology
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• v.20 no.5
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• pp.889-892
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• 2010

We investigated a potential for glucose production from cellulose material using two kinds of hyperthermophilic enzymes, endocellulase (EG) and beta-glucosidase (BGL). Two BGLs, from hyperthermophile Pyrococcus furiosus and mesophile Aspergillus aculeatus, were compared with P. horikoshii endocellulase (EGPh) for complete hydrolysis of cellulose. The combination reactions by each BGL enzyme and EGPh could produce only glucose without the other oligosaccharides from phosphoric acid swollen Avicel (PSA). The combination of both the hyperthermophilic cellulases, BGLPf and EGPh, will be adaptable to a high efficiency system to produce glucose at high temperature.

• Preventive Nutrition and Food Science
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• v.13 no.4
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• pp.266-268
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• 2008

The antimicrobial effect of acidified sodium chlorite (ASC) solution on whole croaker skin was evaluated. Whole croaker skin was treated with ASC (50, 100, 200, 400, and 600 ppm) and distilled water. After 10-minute exposure to 600 ppm ASC, 8% of Gram-negative bacteria survived on the whole croaker sample. Treatment with 50 ppm ASC eliminated all coliforms in the initial load. Immersion treatment with 600 ppm ASC resulted in $1.3\;log\;CFU/cm^2$ greater kill of the initial mesophile loads of control ($2.8\;log\;CFU/cm^2$) than distilled water. Fifty ppm ASC solution produced a 1.6-log reduction of psychrotrophic bacteria. ASC treatment was an effective method for reducing naturally occurring microflora on whole croaker skin.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.157-167
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• 2000

A thermostable chitosanase gene from the isolated strain, Bacillus sp. CK4, was cloned, and its complete DNA sequence was determined. The thermostable chitosanase gene was composed of an 822-bp open reading frame which encodes a protein of 242 amino acids and a signal peptide corresponding to a 30 kDa enzyme in size. The deduced amino acid sequence of the chitosanase from Bacillus sp. CK4 exhibits 76.6%, 15.3%, and 14.2% similarities to those from Bacillus subtilis, Bacillus ehemensis, and Bacillus circulans, respectively. C-terminal homology analysis shows that Bacillus sp. CK4 belongs to the Cluster III group with Bacillus subtilis. The size of the gene was similar to that of a mesophile, Bacillus subtilis showing a higher preference for codons ending in G or C. The functional importance of a conserved region in a novel chitosanase from Bacillus sp. CK4 was investigated. Each of the three carboxylic amino acid residues were changed to E50D/Q, E62D/Q, and D66N/E by site-directed mutagenesis. The D66N/E mutants enzymes had remarkably decreased kinetic parameters such as $V_{max}$ and k$\sub$cat/, indicating that the Asp-66 residue was essential for catalysis. The thermostable chitosanase contains three cysteine residues at position 49, 72, and 211. Titration of the Cys residues with DTNB showed that none of them were involved in disulfide bond. The C49S and C72S mutant enzymes were as stable to thermal inactivation and denaturating agents as the wild-type enzyme. However the half-life of the C211S mutant enzyme was less than 60 min at 80$^{\circ}C$, while that of the wild type enzyme was about 90 min. Moreover, the residual activity of C211S was substantially decreased by 8 M urea, and fully lost catalytic activity by 40% ethanol. These results show that the substitution of Cys with Ser at position 211 seems to affect the conformational stability of the chitosanase.

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.61-70
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• 2020

A eukaryotic microalga was isolated from seawater in Janghang Harbor, Korea and its morphological, molecular, and physiological characteristics were investigated. Due to its simple morphology, no distinctive characters were found by morphological observation, such as light microscope or scanning/transmission electron microscopy (S/TEM). However, molecular phylogenetic evidence inferred from the concatenated small subunit (SSU) 18S rRNA and internal transcribed spacer (ITS) sequence data indicated that the isolate belonged to the newly described Micractinium singularis. Furthermore, it was clustered with Antarctic Micractinium strains and it also showed a psychrotolerant property, surviving at temperatures as low as 5℃. However, its optimal growth temperatures range from 15℃ to 25℃, indicating that this microalga is a mesophile. Additionally, gas chromatography-mass spectrometry (GC/MS) analysis showed that the isolate was rich in nutritionally important omega-3 polyunsaturated fatty acid, and high-performance liquid chromatography analysis (HPLC) revealed that the high-value antioxidant lutein was biosynthesized as an accessory pigment by this microalga, with glucose as the major monosaccharide. Therefore, in this study, a Korean marine M. singularis species was discovered, characterized, and described. It was subsequently added to the national culture collections.

• Genomics & Informatics
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• v.21 no.3
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• pp.34.1-34.10
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• 2023

Nosocomial infections, commonly referred to as healthcare-associated infections, are illnesses that patients get while hospitalized and are typically either not yet manifest or may develop. One of the most prevalent nosocomial diseases in hospitalized patients is pneumonia, among the leading causes of mortality and morbidity. Viral, bacterial, and fungal pathogens cause pneumonia. More severe introductions commonly included Staphylococcus aureus, which is at the top of bacterial infections, per World Health Organization reports. The staphylococci, S. aureus, strain RMI-014804, mesophile, on-sporulating, and non-motile bacterium, was isolated from the sputum of a pulmonary patient in Pakistan. Many characteristics of S. aureus strain RMI-014804 have been revealed in this paper, with complete genome sequence and annotation. Our findings indicate that the genome is a single circular 2.82 Mbp long genome with 1,962 protein-coding genes, 15 rRNA, 49 tRNA, 62 pseudogenes, and a GC content of 28.76%. As a result of this genome sequencing analysis, researchers will fully understand the genetic and molecular basis of the virulence of the S. aureus bacteria, which could help prevent the spread of nosocomial infections like pneumonia. Genome analysis of this strain was necessary to identify the specific genes and molecular mechanisms that contribute to its pathogenicity, antibiotic resistance, and genetic diversity, allowing for a more in-depth investigation of its pathogenesis to develop new treatments and preventive measures against infections caused by this bacterium.

• KSBB Journal
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• v.22 no.5
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• pp.345-350
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• 2007

Phosphosugars are found in all living organisms and are commercially valuable compounds with possible applications in the development of a wide range of specialty chemicals and medicines. In carbohydrate metabolism, fructose 6-phosphate (F6P) is an essential intermediate formed by phosphorylation of 6' position of fructose in glycolysis, gluconeogenesis, pentose phosphate pathway and Calvin cycle. In glycolysis, F6P lies within the glycolysis metabolic pathway and is produced by isomerisation of glucose 6-phosphate. For large-scale production, F6P could be produced from starch using many enzymes such as pullulanase, starch phosphorylase, isomerase and mutase. In enzymatic reactions carried out at high temperatures, the solubility of starch is increased and microbial contamination is minimized. Thus, thermophile-derived enzymes are preferred over mesophile-derived enzymes for industrial applications using starch. Recently, we reported the production of glucose 1-phosphate (G1P) from starch by Thermus caldophilus GK24 enzymes. Here we report the production of F6P from starch through three steps; from starch to glucose 1-phosphate (glucan phosphorylase, GP), then glucose 6-phosphate (phosphoglucomutase, GM) and then F6P (phosphoglucoisomerase, GI). Using 200 L of 1.2% soluble starch solution in potassium phosphate buffer, 1,253 g of G1P were produced. Then, 30% yields of F6P were attained at the optimum reaction conditions of GM : G1 (1 : 2.3), 63.5$^{\circ}C$, and pH 6.85. The optimum conditions were found by response surface methodology and the theoretical values were confirmed by the experiments. The optimum starch concentrations were 20 g/L under the given conditions.

• Korean Journal of Poultry Science
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• v.17 no.1
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• pp.45-52
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• 1990

This study was carried out to establish shelf-life of the chicken product by examining the changes of physico-chemical and microbilogical quality of it during the storage at different temperature and period. Chicken product was stored at $4^{\circ}C$, $10^{\circ}C$, $25^{\circ}C$ and $30^{\circ}C$ for 32 days and its shelf-life was proved to by 2 days at $30^{\circ}C$, 4 days at $25^{\circ}C$ and $30^{\circ}C$ days below $19^{\circ}C$. There was no significant difference in pH and TBA value of the chicken product VBN content and mesophile count were most proper as a quality indicator because they were lower level until 30 days storage. But gas formation rates and sensory evaluation scores were proper as a quality indicator to estimate the shelf-life of the chicken product during the storage at the different temperatures because it was vacuum packaged. Q$_{10}$ value of the chicken product was calculated as 3.99 by examined data of gas formation rates and sensory scores. Estimated shelf-life of chicken product by Q$_{10}$ value was 1 day at $35^{\circ}C$, 4 days at $25^{\circ}C$ 16 days at $15^{\circ}C$ and 64 days at $5^{\circ}C$ respectively.