• Journal of fish pathology
• /
• v.20 no.3
• /
• pp.211-220
• /
• 2007

Red sea bream iridovirus disease (RSIVD) cause massive economic losses in marine aquaculture industry in Korea. The causative agent of this disease (RSIV) infects a wide range of fish species. The aims of this study were to monitor RSIV in wild marine fishes and to give critical information for controling the disease through prophylactic methods. Prevalence of the viral disease, geological distribution and reservoir of the virus were investigated using wild marine fishes captured in southern coast and east china sea for two years. (Polymerase Chain Reaction) PCR results showed that RSIV were detected in 39 (24.3%) out of 160 fish. MCP gene sequences of viral strains isolated in this study were closely related to that of a reference strain, red seabream-K, belonging to Megalocytivirus subgroup Ⅲ. The results suggest that some of wild marine fishes are RSIV carriers and may spread the pathogen directly to fish farmed in coastal area.

• The Korean Journal of Mycology
• /
• v.46 no.2
• /
• pp.177-185
• /
• 2018

The cultivation characteristics of 26 wild strains of Lentinula edodes were investigated for their use as breeding material. Strains NIFoS 68, 136, 1521, 1651, and 2064 showed an above average mycelial growth on potato dextrose agar at 10, 20, and $30^{\circ}C$. NIFoS 411 showed the lowest mycelial growth at $20^{\circ}C$, but the highest growth at $30^{\circ}C$. The rate of weight loss of L. edodes cultivated on sawdust (2 kg) ranged from 13.5 to 47.5%, with the highest rates showed by NIFoS 50 (47.5%), NIFoS 128 (34.5%), and NIFoS 54 (34.4%). Fruiting bodies were produced in nearly all (24/26) strains and productivity ranged from 3 g to 446 g/2 kg medium. Temperature was not significantly correlated with mushroom production or mycelial growth. Larger weight loss correlated strongly with fruit yield. In terms of production, NIFoS 50 (446 g), NIFoS 952 (435 g), and NIFoS 53 (421 g) were useful as breeding material. The NIFoS 667 strain was superior in terms of morphology. NIFoS 670 showed the characteristic yellowish-brown color of fruiting bodies.

• Korean Journal of Food Science and Technology
• /
• v.32 no.2
• /
• pp.431-438
• /
• 2000

Properties of acid tolerance of an adipic acid-resistant mutant, Leuconostoc paramesenteroides (ANaP100) were studied and compared with those of its paired wild type of Leu. paramesenteroides (LPw). The value of protons permeability of LPw after an acid shock at pH 5.0 was 4.3 min, while the value of ANaP100 was 4.8 min at the same pH. The maximal specific activities of ATPase of LPw and ANaP100 were 0.59 unit/mg protein and 0.63 unit/mg protein at pH 6.0, respectively. The release of magnesium ion from the mutant strain was about 27.3% at pH 4 after 2 hrs, while the wild strain was about 52.2% under the same conditions. The contents of $C_{19:0,cyclo}$ and $C_{18:1}$ in a membrane fatty acid of ANaP100 and LPw were higher and lower, respectively, than that of LPw. These results indicated that acid tolerance of ANaP100 was improved in comparison with that of its wild type, LPw.

• The Korean Journal of Mycology
• /
• v.52 no.1
• /
• pp.1-11
• /
• 2024

The present study aimed to screen unrecorded wild yeasts from Jeju lsland and Jangsado on the southern coast of Korea, and to investigate their microbiological characteristics. To date, Coniozyma leucospermi JJD37-2, Hanseniaspora thailandica JJD44-1, Kluyveromyces nonfermentans JJD15-1, Kockovaella fuzhouensis JJD47-3, Vishniacozyma heimaeyensis JJD8-4, Candida carpophila JSDH24-1, Wickerhamomyces strasburgensis JSDH34-2, Candida savonica HJD6-4, and Candida karawaiewii YP23-3 have not been previously recorded in Korea. In the present study, we investigated the microbiological characteristics of these previously unrecorded yeasts. Except for W. strasburgensis JSDH34-2 strain, none of the strains formed spores, and only the C. leucospermi JJD37-2 strain formed pseudomycelia. Almost all strains grew well in yeast extract-peptone-dextrose (YPD) medium, potato dextrose (PD) medium and yeast extract-malt extract (YM) media. C. carpophila JSDH24-1 and W. strasburgensis JSDH34-2 also grew well in YPD medium containing 10% NaCl. H. thailandica JJD44-1 is fermented to produce glucose, fructose and mannose.

• Microbiology and Biotechnology Letters
• /
• v.34 no.3
• /
• pp.244-249
• /
• 2006

In order to select the best strains to have the feasibility of Cheonghju brewing, 10 wild type yeast strains from 300 different types of Nuruk were investigated on their ethanol resistance, resistance to glucose and flocculation. The amounts of alcohol, organic acids, and volatile compounds, Brix, pH were also examined for the alcoholic beverages made with the 10 selected strains. Almost all strains showed alcohol production activities in the medium containing 18%(v/v) ethanol and 29%(w/v) glucose. The strains 90-2 showed a higher flocculation activity than other strains. Strains 54-3, 90-2 and 91-5 produced more alcohol than control strain (7.42%(w/w)) when fermented with wild type yeast strains. In addition, alcoholic beverages containing low acetic acid also showed low levels of total acidity. GC/MS analysis of the product showed 4 alcohols, 11 esters and 1 acid as volatile compounds. Selected strains were tentatively identified as Phichia sydowiorum (91-5), Zygosaccharomyces cidri (192-2 and 271-4), and as Saccharomyces cerevisiae (18-2, 54-3, 90-2, 91-2, 98-2, 99-5 and 272-7) by BIIOLOG method.

• Korean Journal of Environmental Biology
• /
• v.20 no.3
• /
• pp.237-244
• /
• 2002

To analyze proteins related to antifungal activity, SAR01 strain was isolated from seaweed and identified as Streptomyces sp. from the result of FAME (fatty acid methyl ester) analysis. The isolated strain had antifungal activities against T species of plant pathogenic fungi. Antifungal activity deficient mutant (SAR 535) of Streptomyces sp. SAR01 was induced by gamma radiation $(^{60}Co,\;5kGy)$. By 2 D electrophoresis analysis, 6 protein spots were found in wild strain (SAR01) but these spots disappeared in mutant strain (SAR535). Among them, 5 proteins showed similarities to heat shock protein 70(HSP70), Fe-containing superoxide dismutase II (Fe- SODII), ribosome recycling factor (RRF), 10 kDa chnperonin (GroES) and inorganic pyrophosphatase (PPAse), respectively. It suggested that the above 6 proteins could be closely related to the antifungal activity of Streptomyces sp. SAR01.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.4
• /
• pp.767-774
• /
• 2010

In this study, the problems of high caloric content, increased maturation time, and off-flavors in commercial beer manufacture arising from residual sugar, diacetyl, and acetaldehyde levels were addressed. A recombinant industrial brewing yeast strain (TQ1) was generated from T1 [Lipomyces starkeyi dextranase gene (LSD1) introduced, ${\alpha}$-acetohydroxyacid synthase gene (ILV2) disrupted] by introducing Saccharomyces cerevisiae glucoamylase (SGA1) and a strong promoter (PGK1), while disrupting the gene coding alcohol dehydrogenase (ADH2). The highest glucoamylase activity for TQ1 was 93.26 U/ml compared with host strain T1 (12.36 U/ml) and wild-type industrial yeast strain YSF5 (10.39 U/ml), respectively. European Brewery Convention (EBC) tube fermentation tests comparing the fermentation broths of TQ1 with T1 and YSF5 showed that the real extracts were reduced by 15.79% and 22.47%; the main residual maltotriose concentrations were reduced by 13.75% and 18.82%; the caloric contents were reduced by 27.18 and 35.39 calories per 12 oz. Owing to the disruption of the ADH2 gene in TQ1, the off-flavor acetaldehyde concentrations in the fermentation broth were 9.43% and 13.28%, respectively, lower than that of T1 and YSF5. No heterologous DNA sequences or drug resistance genes were introduced into TQ1. Hence, the gene manipulations in this work properly solved the addressed problems in commercial beer manufacture.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.6
• /
• pp.1197-1206
• /
• 2005

Vibrio vulnificus is an opportunistic pathogen that causes a septicemia and expresses numerous virulence factors, in which luxS and smcR are genes encoding for components responsible for quorum-sensing regulation. In the present study, null mutants were constructed with lesions in each or both of these two genes from the V. vulnificus Vv$\Delta$Z strain, which is a lacZ$^{-}$ and chloramphenicol/streptomycin-resistant derivative of the wild-type ATCC29307 strain, and their phenotypes related to virulence were compared with those of the parental cells. $LD_{50}$ and histopathological findings of luxS-, smcR-, or luxS- smcR- deficient mutant were not different from those of the parent strain, a lacZ-deficient streptomycin-resistant strain in mice. However, time of death in mice was delayed, and numbers of bacteria survived in bloodstream after intraperitoneal injection in mice were decreased by mutation, especially luxS and smcR double mutant (VvSR$\Delta$ZSR). These phenomena were supported by increased serum sensitivity and delayed bacterial proliferation in both murine blood and iron-restricted medium. These results suggest that the luxS and luxR homologous genes in V. vulnificus could playa role in bacterial survival in host by enhancing proliferation and adjusting to changed environment.

• Microbiology and Biotechnology Letters
• /
• v.47 no.4
• /
• pp.565-573
• /
• 2019

Production of biofuels and value-added materials from cellulosic biomass requires the development of a microbial strain capable of efficiently fermenting mixed sugars. In this study, the natural xylose fermenting yeast, Pichia stipitis, was evolved to simultaneously ferment cellobiose and xylose. Serial subcultures of wild-type P. stipitis in 20 g/l cellobiose were performed to increase the rate of cellobiose consumption. A total of ten rounds of the serial subculture led to the isolation of an evolved strain fermenting cellobiose significantly faster than the parental strain. The evolved strain displayed enhanced ethanol yield from 0 to 0.4 g ethanol/g cellobiose. The evolved P. stipitis simultaneously fermented cellobiose and xylose in batch fermentation. The genetic information of our evolved P. stipitis would be valuable in the development of a microbial host for the production of biofuels and biomaterials from cellulosic biomass.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 2000.04a
• /
• pp.53-60
• /
• 2000

Strain BH5 was isolated from naturally fermented Kimchi and identified as a bacteriocin producer, which has bactericidal activity against Micrococcus flavus ATCC 10240. Strain BH5 was identified tentatively as Lactococcus lactis by the API test and some characteristics. Lactococcus lactis BH5 showed a broad spectrum of activity against most of the non-pathogenic and pathogenic microorganisms tested by the modified deferred method. The activity of lacticin BH5, named tentatively as the bacteriocin produced by Lactococcus lactis BH5, was detected at the mid-log growth phase, reached its maximum during the early stationary phase, and decreased after the late stationary phase. Lacticin BH5 also showed a relatively broad spectrum of activity against non-pathogenic and pathogenic microorganisms as tested by the spot-on-lawn method. Its antimicrobial activity on sensitive indicator cells was completely disappeared by protease XIV or ${\alpha}$-chymotrypsin. The inhibitory activities of lacticin BH5 were detected during treatments up to 100$^{\circ}C$ for 30 min. Lacticin BH5 was very stable over a pH range of 2.0 to 9.0 and was stable with all the organic solvents examined. The cell concentration and bacteriocin production in strain BH5 were maximum when grown at 30$^{\circ}C$ in a modified MRS medium supplemented with 0.5% tryptone, 1.0% yeast extract, and 0.5% beef extract as nitrogen sources. It demonstrated a typical bactericidal mode of inhibition against Micrococcus flavus ATCC 10240. Lacticin BH5 was purified through ammonium sulfate precipitation, ethanol precipitation, and CM-Sepharose column chromatography. The apparent molecular mass of lacticin BH5 was estimated to be in the region of 3.7 kDa, by the direct detection of bactericidal activity after SDS-PAGE. Mutant strain NO141 which was isolated by nitrosoguanidine mutagenesis produced about 4 fold more bacteriocin than the wild type.