• Research in Plant Disease
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• v.10 no.1
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• pp.8-12
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• 2004

The diseased ginseng plants, their trunks fall down anil roots rot, were observed in ginseng cultivation field at Bongwha, Kyungbuk. Inoculation of the bacterium isolated from root rot lesion induced a range of symptoms on leaves, trunks and roots; The bacterium caused wilting with chlorosis and black discoloration on leaves, empty of inside trunks and rot on roots. The bacterium was identified as Serritia liquefaciens based on the morphologcal and physiological characteristics. This is the first report in Korea on roots rot of ginseng occurred by S. liquefaciens.

• Food Science of Animal Resources
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• v.34 no.4
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• pp.543-551
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• 2014

The aim of this study was to evaluate the effect of proteolytic (Serratia liquefaciens, match %: 99.39) or lipolytic (Acinetobacter genomospecies 10, match %: 99.90) psychrotrophic bacteria (bacterial counts, analysis of free fatty acids (FFA) and analysis of free amino acids) on the microbial and chemical properties (yogurt composition), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of yogurt during storage. Yogurts were prepared with raw milk preinoculated with each psychrotrophic bacteria. The total solid, fat, and protein content were not affected by preinoculation, but the pH of yogurt preinoculated with psychrotrophic bacteria was higher than in control. There was a dramatic increase in short chain free fatty acids among FFA in yogurt with Acinetobacter genomospecies 10. For 14 d of cold storage condition, SCFFA was 25.3 mg/kg to 34.4 mg/kg (1.36 times increased), MCFFA was 20.4 mg/kg to 25.7 mg/kg (1.26 times increased), and LCFFA was 240.2 mg/kg to 322.8 mg/kg (1.34 times increased). Serratia liquefaciens (match %: 99.39) in yogurt caused a greater accumulation of free amino acids (FAA), especially bitter peptides such as leucine, valine, arginine, and tyrosine, but SDS-PAGE showed that the inoculation of Serratia liquefaciens did not affect the degree of casein degradation during storage. Taken together, the excessive peptides and FFA in yogurt generated from psychrotrophic bacteria could develop off-flavors that degrade the quality of commercial yogurt products.

• Journal of Microbiology and Biotechnology
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• v.17 no.3
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• pp.408-413
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• 2007

Putrescine has a negative effect on health and is also used as an indicator of quality on meat products. We investigated the genes involved in putrescine production by Serratia liquefaciens IFI65 isolated from a spoiled Spanish dry-cured ham. We report here the genetic organization of its ornithine decarboxylase encoding region. The 5,506-bp DNA region showed the presence of three complete and two partial open reading frames. Putative functions have been assigned to several gene products by sequence comparison with proteins included in the databases. The second gene putatively coded for an ornithine decarboxylase. The functionality of this decarboxylase has been experimentally demonstrated by complementation to an E. coli defective mutant. Based on sequence comparisons of some enterobacterial ornithine decarboxylase regions, we have elaborated a hypothetical pathway for the acquisition of putrescine biosynthetic genes in some Enterobacteriaceae strains.

• Korean Journal of Microbiology
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• v.29 no.3
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• pp.195-198
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• 1991

Isolation and identification of mesophilic and psychrotrophic bacteria distributed in Korean refrigerated beef were attempted. Total isolated colonies were 192, and identified as 5 genera and 10 species. Among them, mesophilic bacteria were Enterobacter aerogenes, E. agglomerans, Serratia liquefaciens, Proteus mirabilis, and "psychrotrophic" bacteria were Pseudomons fluorescens, P. putida, P. pickettii, P. mendocina, P. stutzeri, Alcaligenes faecalis. Dominant species was Serratia liquefaciens as mesophiles, and Pseudomonas putida as psychrotroph.chrotroph.

• Journal of radiological science and technology
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• v.31 no.4
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• pp.329-335
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• 2008

Distribution of microorganisms were examined for the bucky tables in the radiology rooms of the department of radiological technology, the aprons, handles of various apparatus, handles of mobile radiological apparatus, and hands of the radiological technologists. As a result, relatively larger amounts of bacteria were found on the handles of the mobile radiological apparatus and the aprons. Among the isolated bacteria, Acinetobacter baumanni (7.3%), Klebsiella pneumoniae (6.7%), Staphylococcus aureus (3.9%), Serratia liquefaciens (1.7%), Enterobacter cloaceae (0.6%), Providenica rettgeri (0.6%) are known as the cause of nosocomial infection (hospital acquired infection). In addition, similar colonies were also found on the hands of the radiological technologists such as microorganisms of Klebsiella pneumoniae (8.4%), Staphylococcus aureus (6.6%), Yersinia enterocolotica (5.4%), Acinetobacter baumanni (4.2%), Enterobacter cloaceae (2.4%), Serratia liquefaciens (1.8%), Yersinia pseuotuberculosis (18%), Enterobacter sakazakii (1.2%), and Escherichia coli (0.6%). In particular, this result indicates clinical significance since Staphylococcus aureus and Escherichia coli show strong pathogenicity. Therefore, a continuous education is essential for the radiological technologists to prevent the nosocomial infection.

• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.87-91
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• 1996

The optimum temperature and pH for the enzyme activity were 45$^{\circ}C$ and 10.0, respectively. The enzyme was stable in a pH range of 5 to 10, and 62% of its activity was lost on heat treatment of 60$^{\circ}C$ for 20 min. The activity of the purified enzyme was inhibited by $Fe^{2+},\;Zn^{2+}\;and\;Pb^{2+}$, and slightly activated by $Mn^{2+}\;and\;Ca^{2+}$. ${\gamma}$-Chloromercuribenzoic acid, 2,4-dinitrophenol and $H_{2}O_{2}$ did not show inhibitroy effect on the lipolytic activity of the alkaline lipase but ethylenediaminetetraacetic acid inhibited the enzyem activity. This suggested that the enzyme have metal group in its active site. Sodium salts of bile acids stimulated the enzyme activity. Analysis of hydrolyzates of olive oil after the reaction revealed that Serratia liquefaciens AL-11 produced non-specific lipolytic enzyme.

• Food Science of Animal Resources
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• v.33 no.6
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• pp.772-780
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• 2013

The aim of this study was to investigate the effect of season and location on activities of enzyme produced by psychrotrophic bacteria isolated from raw milk located in Kyunggi region of South Korea. Agar diffusion and colorimetric methods were used for the lipase and protease activities of psychrotrophic bacteria. Intensities of dark blue and transparent ring around colony were compared for activity measurement. Nutrient agar with 1% skim milk added was employed for measuing protease activity. 14 strains of Arthrobacter russicus with lipase activity and 19 strains of Chryserobacterium shigense with protease activities were found to be present. It was found that Acinetobacter genomospecies 10 (match %: 99.90) isolated from B region in fall was the most lipolytic species, whereas Serratia liquefaciens (match %: 99.39) isolated from the same region in spring was the most proteolytic species. Growth curve of Acinetobacte and Serratia liquefaciens was a typical sigmoidal form. Lipase activity increased with incubation time, but its activity began to drop at stationary to motality phase. Optimum condition for incubation time, pH and temperature for extracellular lipase from Acinetobacter genomospecies 10 (match %: 99.90) was 12 h, 8.5, and $45^{\circ}C$, respectively. Extracellular protease from Serratia liquefaciens (match %:99.39) had the same optimum incubation time and pH as extracellular lipase, but optimum temperature was $35^{\circ}C$.

• Food Science of Animal Resources
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• v.33 no.4
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• pp.542-548
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• 2013

This study was conducted to investigate effect of psychrotrophic bacteria on the quality of raw milk. Acinetobacter genomospecies 10 was selected as lipolytic species, and Serratia liquefaciens as proteolytic species. Lipase present in inoculated raw milk with Acinetobacter genomospecies 10 did not affect total solid and fat contents. However, the free fatty acid (FFA) content, especially short chain FFAs, of milk with Acinetobacter genomospecies 10 was dramatically increased. FFAs produced by lipolysis of milk fat are important in flavor of dairy products, excessive lipolysis occurring in milk and dairy products could cause off-flavor, and produced FFAs may have an underiable effect on their flavor. In addition, protease influenced the quality of inoculated raw milk with Serratia liquefaciens. In degradation patterns of casein by SDS-PAGE analysis from inoculatred raw milk with Serratia liquefaciens, casein content was gradually decreased during storage at $4^{\circ}C$, and extensive degradation of $\kappa$-casein was observed on the storage day of 13. The free amino acids such as leucine, valine, arginine, and tyrosine were dramatically increased, which causes bitter taste in raw milk. These excessive peptides in dairy products, produced by psychrotrophic bacteria, can be possible to develop off-flavors and be responsible for gelling of milk by degradation.

• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.695-701
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• 1995

An alkaline lipase producing bacteria was isolated from soil and identified as Serratia liquefaciens AL-11. from the results of analysis of its morphological, biochemical and physiological properties. This strain showed the highest productivity of alkaline lipase when grown at pH 9.0 and 30$\circ$C for 42 hours in the medium of 1% peptone, 0.5% tryptone, 0.9% yeast extract, 1% starch, 1% tween 80, 0.05% CaCl$_{2}$ and 0.05% NaCl. The enzyme was purified by ammonium sulfate treatment, Sephadex G-100 gel filtration and DEAE-Sephadex A-50 column chromatography. The specific activity of the purified enzyme was 27 unit/mg protein and the yield of enzyme activity was 61.3%. The homogeneity of the purified enzyme was verified by polyacrylamide gel disc electrophoresis. Molecular weight of the purified enzyme was estimated about 53,000 by sodium dodecyl sulfate- polyacrylamide gel electrophoresis. This enzyme is composed of 17 amino acids of which glycine, proline and glutamic acid were three miajor acids.

• Journal of Food Hygiene and Safety
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• v.14 no.3
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• pp.227-232
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• 1999

A total of 136 coliform bacteria isolated from spring water (112 strains) and ground water (24 strains), submitted to Seoul Health and Environmental Research Institute from June to July in 1997, were characterized biochemically and microbiologically. Colonical characteristics of each isolate were also noted, including color and texture on EMB agar. Among the 136 isolates, 50.7% were greenish metallic sheen color, 44.2% were pink and 5.1% were violet. The sixty four percent were smooth, 34.6% were mucoid and 0.7%. were rough. Twenty three bacterial species were identified by IMViC and API 20E test. Among the 136 coliform bacteria known to species, 39 isolates (28.6%) were Escherichia spp., 32 isolates (23.5%) were Klebsiella ssp., 30 isolates (22.1%) were Enterobacter spp., 19 isolates (14.0%) were Serratia spp., 6 isolates (4.4%) were Citrobacter spp., 4 isolates (3.0%) were Kluyvera spp. and 7 isolates (5.1%) were other bacterial species. Strains, which were gas-positive in lactose broth but gas-negative in Kligler Iron Agar were Ent. intermedium, Ser. liquefaciens, Ser. marcescenes and Salmonella arizoae. Strains, which were H2S production were also Kleb. pneumoniae, Kleb. oxytoca, Kleb. ornithinolytica, Ent. sahazahii, Ent. cloacae, Ser. liquefaciens, Ser. fica ria, Cit. freundii and Sal. arizoae. In the present study, most of coliform isolated from spring and ground water were E. coli, Klebsiella spp. and Enterobacter spp. Since coliform with pink colony in EMB agar was isolated as frequent as coliform with greenish metallic sheen colony, coliform with pink colony should be considered as important colony. Our results suggested that new coliform strains may be emerging on the basis of biochemical and microbiological testes.