• Korean Journal of Food Science and Technology
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• v.40 no.1
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• pp.101-105
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• 2008

Enterobacter sakazakii is implicated in severe forms of neonatal infections such as meningitis and sepsis. This organism has been isolated from a wide range of foods, including cheese, vegetables, grains, herbs, and spices, but its primary environment is still unknown. Generally, dried infant milk formula has been epidemiologically identified as the source of E. sakazakii. Sunsik (a powdered mixture of roasted grains and other foodstuffs) is widely consumed in Korea as a side dish or energy supplement. Sunsik is consumed without heat treatment; thus, lacking an additional opportunity to inactivate foodborne pathogens. Therefore, its microbiological safety should be guaranteed. In this study, the prevalence of E. sakazakii was monitored in 23 different sunsik component flours, using FDA recommended methods; but E. sakazakii medium (Neogen) and Chromogenic E. sakazakii medium (Oxoid) were used as the selective media. In total, presumptive E. sakazakii strains were isolated from 8 different sunsik powders. Subsequently, an API 20E test was conducted, and 15 strains from 5 different sunsik flours (sea tangle, brown rice, non-glutinous rice, cheonggukjang, dried anchovy) were confirmed as E. sakazakii. Fifteen strains were again confirmed by PCR amplification, using three different primer sets (tDNA sequence, ITS sequence, 16S rRNA sequence), and compared to ATCC strains (12868, 29004, 29544, 51329). They were once again confirmed by their enzyme production profiles using an API ZYM kit. Finally, RAPD (random amplified polymorphic DNA)-genotyping was carried out as a monitoring tool to determine the contamination route of E. sakazakii during processing.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.6
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• pp.873-883
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• 2008

In this study, we assessed consumers' recognition of frozen foods via a survey study, and monitored the contamination levels of total aerobic bacteria and Escherichia coli in imported and domestic frozen seafoods obtained from five whole sale markets in Seoul. A questionnaire used to assess the perception of frozen food safety and the attitude towards frozen food usage was developed and distributed to 350 adults. A total of 324 questionnaires were subjected to frequency analysis and a chi-square test, using SPSS for Windows. The results of our survey study demonstrated that 44.6% of the respondent consumed frozen processed foods two to three times per month, with dumplings being the most frequently purchased. 70.5% of the respondents selected "convenient cooking" as the principal reason for their frozen food purchases. 58% of the respondents believed that frozen processed food is not safe to eat as the result of food additives and changes in quality during the shelf life period. Consumers most profoundly preferred frozen seafood originating from America, and preferred that from China least profoundly (81.2%). Microbiological analyses demonstrated that the aerobic plate counts of frozen seafood, regardless of origin, fulfill the standard requirements except for one frozen clam (6.6 Log CFU/g), which was a heated-frozen domestic product. In addition, E. coli was isolated from frozen cooked mussels, frozen raw clams and squids, thus indicating that more strict hygienic regulation for frozen seafoods will be necessary to protect the consumer in both domestic and foreign markets.

• Journal of Life Science
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• v.19 no.8
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• pp.1177-1182
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• 2009

In order to establish in vitro infection model for research of plant pathogen based on tissue softening disease in napa cabbage, eighty independent bacterial strains were isolated from the softened napa cabbage tissues. Eight bacterial isolates were primarily screened with the generation of reproducible tissue softening disease to fresh napa cabbages within 24${\sim}$48 hours after inoculation. Through various microbiological biochemical and morphological examinations, three Gram (-) isolates which harbor independent biological properties were finally chosen, and named as RBI, RB2 and RB6. Collective results obtained from API 20E test and analyses of VITEK 2 COMPACT and nucleotide sequences of 165 rRNA of each isolate proposed that isolates RBI and RB2 are close to the Erwinia carotovora subsp. odorifera, and RB6 is close to the Erwinia carotovora subsp. carotovora. These isolates grew optimally at $30^{\circ}C$ with neutral pH culture condition. The isolates caused softening tissue disease with dose-dependent manner regardless of pre-surface damages of napa cabbage. Minimum dose to cause soft rot disease for RBI, RB2 or RB6 were $8.0{\times}10^8$ CFU/mt $10^9$ CFU/ml or $4.7{\times}10^6$ CFU/ml respectively. These isolates caused tissue softening disease to eggplant, paprika and napa cabbage out of 14 different tested vegetables, indicating that these isolates damages specific plant tissues. The bacterial isolates obtained in this research and in vitro plant infection model will be adapted in the understanding of the mechanism of pathogenesis by plant pathogen.

• Korean Journal of Microbiology
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• v.52 no.1
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• pp.25-31
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• 2016

An enterococci selective medium was developed to detect the presence of enterococci for use as a fecal contamination indicator. Among several media which have been known to detect enterococci, the following 9 different kinds of media were selected: Enterococci Confirmatory agar, Azide dextrose agar, Bromocresol-purple azide agar, Esculin bile agar, Citrate azide tween carbonate agar, KF Streptococcus agar, BROLACIN agar, Kanamycin esculin azide agar, and Membrane filter Enterococcus selective agar. Various components from the nine media were mixed to develop a more effective enterococcus selective medium. The newly developed medium named as 'Enterococcus Mixed medium' was more effective than the previous 9 media. Enterococci strains (Enterococcus avium KACC 10788, Enterococcus faecium KACC 11954, Enterococcus saccharolyticus KACC 10783, Enterococcus durans KACC 10787, Enterococcus faecalis KACC 11304, and Enterococcus hirae KACC 10779) and non-enterococci strains (Escherichia coli KACC 10005, Staphylococcus aureus subsp. aureus KACC 10768, and Bacillus subtilis KACC 10111) were used to test the new medium. As a result, the enterococci strains grew well on the Enterococcus Mixed medium whereas the non-enterococci strains did not grow well on it. Additionally, growth of enterococci with freshwater and seawater samples was observed to be good on the Enterococcus Mixed medium. The result of this study confirmed that the Enterococcus Mixed medium was effective in detecting the target enterococci.

• Food Science of Animal Resources
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• v.25 no.1
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• pp.45-51
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• 2005

This study was carried out to get the informations on microbes and protein extractability through comparing the quality attributes of Hanwoo fed in Korea, Hanwoo fed in Japan and Japanese Wagyu. The fresh beefs were stored at 4±l℃ for 13 days. In microbiological test, the total plate counts were higher in rump than in other beef portion as loin, chuck (p<0.000l). The number of psychrotrobes in the rump were maintained high levels (p>0.0001) for storage period, whereas the loin from Hanwoo fed in Korea, Hanwoo fed in Japan and Wagyu were lowest levels. The number of E. coli were no significantly different among the samples. In lactic acid bacteria, the loin form 3 grade Hanwoo (K3) had highest levels (p<0.0001). Comparing to the protein extractability, water soluble proteins were high in chuck (p<0.001). In the case of loin, water soluble proteins of K3 (3 grade Hanwoo) and Wagyu were high as 3.010 mg/g and 2.977 mg/g, respectively (p<0.001). Salt soluble protein of K1 (1 grade Hanwoo) was high as 7.437 mg/g (p<0.0001).

• Korean Journal of Microbiology
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• v.41 no.1
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• pp.18-23
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• 2005

The purpose of this work was to investigate the physiological characteristics of Lactobacillus sp. JK-8 isolated from a shrimp aquaculture pond. The strain JK-8 was grown on MRS media, and morphological and physiological characteristics of the strain were examined. The bacterium was identified as a strain of the genus Lactobacillus on the basis of BIOLOG test. Strain JK-8 produced both lactic acid and acetic acid, which were responsible for the pH decrease during growth. Concentrations of lactic acid and acetic acid increased to 192.8 mM and 43.6 mM, respectively, and the initial pH 7.0 of the cultures decreased to 3.8 at the end of incubaction. The bacteriocidal effect against eight target bacteria was examined with 5-fold concentrated culture supernatants. All bacteria tested in this work were completely killed within 3 hrs after treatment with the culture supernatant. The bacteriocidal effects were clearly observed, only when the pH of the culture supernatants were not adjusted. HPLC was used to reslove lactic acid and acetic acid in the culture solution, and GC-MS was used to verify the metabolites.

• Korean Journal of Microbiology
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• v.30 no.5
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• pp.339-346
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• 1992

These studies were carried out to identify Bacillus cereus group 1..5-] strain isolated from 5uyeong Bay. This strain was differentiated from B. cereus group using conventional, API system and fatty acid composition analysis. Colony characteristics were opague. mucoid, entire margin. convex. circular and non hemolysis on sheep blood agar plates, and were observed with central spore forming positive bacilli in a Gram stained preparation. and had no motility. The carbohydrates tested; glucose.maltose, and sucrose were assimilated but neither trehalose nor salicin were assimilated. This strain ultilized gelatin and was also inhibited by 6.5% NaCI. The results of biochemical examination were differented from B. cereus group LS-1 compared with others B. cereus group. The fatty acid composition contained major amounts of branched chain acids. iso $C_{15}$ and iso $C_{13}$ and the range of chain length was $C_{12}$ to C"$C_{17}$ and n$C_{15}$, acid was not detected. Automated fatty acid computer profile indicated "B. mycoides GC subgroup B of 0.312 similarity index." The results agreed with other research cases. On the other hand. A TB computer prolile index of API system (API 50 CHB & API 20E) identified" Doubtful profile of 99.7% B. firmus" . These results were presented with considerable discrepancies between API system and fatty acid analysis. With 67 biochemical characters. the similarity matrix of B. mycaides (KCTC 1033). B. thuringiensis (KCTC 1033). B. cereus (5-3) and B. mycoides (S-12) showed 42%. 42%. 59%, and 52%. respectively. Through the key tests and fatty acid analyses. we could notice the appearance of B. mycoides of the B. cereus group and this leads us to suspect the existence of a new biotype B. mycoides.

• Korean Journal of Microbiology
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• v.30 no.5
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• pp.360-365
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• 1992

Clinical isolates of 8 ofloxacin resistant Staphylococcus auresu (ORSA) were subjected to MIC test, Southern analysis on gyrA locus and nucleotide sequence analysis of 290 bp of gyrA gene (gyrA-290) spanning amino acid 26 to 121 in order to understand the mechanism of quinolone resistance in Staphylococcus aureus. ORSAs showed highlevel resistance against quinolones (8-250 fold increase of MICs) and also significant resistance agianst ${\beta}-lactams$ (2-32 fold increase of MICs). However, ORSs did not show any change in sensitivity agianst vancomycin. Southern analysis of ORSAs with HindIII, PstI and AluI revealed RFLPs on gyrA locus. In order to further analyze the gyrA gene, gyrA-290 was amplified by PCR and cloned to pTZ vector. Subsequent nucleic acid sequence analysis of gyrA-290 demonstrated a point mutation of C to T resulting amino acid change of Ser-84 to Leu-84 in all 8 ORSA strains. The substitution at 84th amino acid of tyrase A might confer one mechanism of high level quinolone resistance in Staphylococcus aureus.

• Korean Journal of Microbiology
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• v.36 no.4
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• pp.299-305
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• 2000

Degradation behavior of the three commercial biodegradable polymers, namely poly(3-hydroxybutyrate) (PHB) Sky-Green/sup R/ (SG) and Mater-Bi/sup R/ (MB) was investigated using bacteria isolated from activated sludge and farm soil. Three PHB degrading bacteria, three SG degrading bacteria and one MB degrading bacteria were isolated. The PHB degrading bacteria were identified to be Flavimonas oryzihabitans, Corynebacterium pseudodiphtheriticum and Micrococcus diversus, while Pseudomonas vesicuraris, Pasteurlla multocida and Flavobacterium odoratum were identified as SG degrading bacteria. As for MB, Pseudomonas vesicuraris was isolated. The shake flask test for 28 days indicated that the rate of biodegradation of PHB, SG and MB in terms of weight loss were about 44∼69% 25∼32% and 29% respectively. The surface morphology of PHB, SG andMB films before and after degradation by microorganisms in an activated sludge soil was observed under SEM, demonstrating that the film surface had a very porous structure, and that microorganisms colonized heavily on the film surface. TOC and pH variation as a result of abiotic hydrolysis, or microbial growth in the absence of the polymers were compared to those due to degradation by F. oryzihabitans. Abiotic hydrolysis of PHB was three times as fast as that of SG and MB. Addition of yeast extract to the basal liquid medium accelerated the biodegradation of the polymers. Biodegradation of PHB was always faster than that of SG and MB irrespectively of the presence of yeast extract in the basal liquid medium.

• Korean Journal of Microbiology
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• v.27 no.1
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• pp.1-9
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• 1989

The locations of 5' ends as well as the splicing pattern of viral poly A(-) 19S RNA from monkey cells infected with SV40 were determined by a modification of primer extension method. The 5' end of this RNA mapped at the major cap site at nucleotide residue 325, used most frequently by SV40 late RNAs. The intron from nt.373 to nt.558 was removed as the ordinary cytoplasmic poly A(+) 19S RNA. The 3'end of this RNA was very heterogeneous and distributed over 1 kb upstream of polyadenylation site, as determined by S1 nuclease mapping. The reason for this normally initiated and spliced RNA to accumulate in the nucleus was investigated. In order to test whether the presence of unused 3' splice region on this RNA caused such subcellular distribution, cells were transfected with SV40 mutant KNA containing deletion around 3' splice site. The RNA deleted of 3' splice region accumulated mainly in the cytoplasm. This accumulation did not result from the increased stability of the RNA due to the deletion, since the wild type and mutant RNAs exhibited similar half lives after chase with actinomycin D. Therefore it is likely that the 19S spliced RNA is hindered from being transported into the cytoplasm due to some pre-splicing complexes formed at the unused 3' splice site.