• Journal of Food Hygiene and Safety
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• v.24 no.4
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• pp.307-311
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• 2009

The objectives of this study were to compare the biochemical profiles with biogroups for the identification of Cronobacter spp. (formally known as Enterobacter sakazakii) isolates using biochemical identification kits. A total of 38 Cronobacter spp. contained 5 clinical, 31 food, and 2 environmental isolates were used. All isolates were identified as Cronobacter spp. with the Vitek II system and ID 32E kit. The API 20E kit identified all isolates as Cronobacter spp. but the percentage identification was 51.1% for 16 of 38 isolates. These strains were contained to Biogroup 2, 9, 10, and 11. The utilization of inositol is a factor determining the percentage identification of Cronobacter spp. with the API 20E kit.

• Journal of Food Hygiene and Safety
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• v.15 no.2
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• pp.128-136
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• 2000

Twenty-four Vibrio strains were isolated from imported frozen seafoods and identified according to their physiological and biochemical properties. They included two V cholerae non-01 sp., two V. diazotrophicus sp., one V. hollisae sp., five V. natriegens sp., eight V. fluvialis sp., and four V. nereis sp.. Two of them were not identified as Vibrio species. When these strains were tested using API-2OE kit fur identification, however, only the results for two V. cholerae and five of the V. fluvialis strains matched the results obtained previously. Due to the importance of detecting V cholerae from foods, phylogenetic identification of the strains was attempted based on restriction fragment length polymorphism (RFLP) of the 16S rDNAs amplified by PCR. The results suggested that the two strains had identical RFLP patterns which were more closely related to that of V. proteolyticus than V. cholerae. The problems associated with identification of pathogens originated from seafoods demand development of accurate and rapid identification methods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.630-634
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• 2001

The effect of chitosan on the quality of processed milk was investigated to minimize the microbial spoilage occurred by contaminant bacteria and yeast. Yeast and bacteria isolated from commercial processed milk were identified as Saccharomyces cerevisiae and Pseudomonas fluoresence by Api 20C and 20E Aux kit, respectively. The growth of isolated yeast and bacteria inhibited in YM broth and TSB containing 0.03% chitosan at $25^{\circ}C$ and $37^{\circ}C$ for 24hour, respectively. Viable cells of processed milk artificially contaminated with Saccharomyces cerevisiae and Pseudomonas fluoresence were reduced about 2~3 l$og_{10}$ cycle by addition of 0.03% chitosan pH, acidity and total bacteria were changed from after storage for 10 day at $4^{\circ}C$, 7 day at 1$0^{\circ}C$ and 1day at $25^{\circ}C$in chitosan no added processed milk during storage for 15day. But, The change of physico-chemical and microbiological charcteristics could not observe in 0.3% chitosan added processed milk during storage 15 day at $4^{\circ}C$, 1$0^{\circ}C$ and $25^{\circ}C$, respectively. The sensory quality of processed milk with 0.3% chitosan was different significantly from control in taste, texture and overall acceptability(p<0.05).

• 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.

• Korean Journal of Food Science and Technology
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• v.43 no.2
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• pp.161-168
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• 2011

The purpose of this study was to evaluate microbiological contamination of fresh vegetables in Korea. Twenty types of vegetables were tested for total aerobic bacteria, coliforms, Escherichia coli, yeast and mold, and pathogenic bacteria such as Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Salmonella, E. coli O157:H7, Cronobacter sakazakii, Shigella, and Campylobacter. Levels of total aerobic bacteria and coliform on 20 vegetables were between 3.74 and 8.04 log CFU/g, and 0.16 and 5.02 log CFU/g, respectively. The highest contamination levels of total aerobic bacteria were observed on water dropwort, sprouts, mungbean sprout, and ballflower root. There was no significant difference (p>0.05) in microbial contamination levels of total aerobic count, coliform, E. coli, yeast and mold between organic and nonorganic vegetables. When isolation methods using selective agars were applied, L. monocytogenes, B. cereus, Salmonella and Campylobacter were isolated from some fresh vegetable samples. Results of API kit tests showed that L. monocytogenes was identified on Chinese cabbage, cucumber, soybean sprouts, and iceberg lettuce while Salmonella was identified on Korean leek. Furthermore, Campylobacter jejuni was also identified in more than 50 of the 100 samples. However, when positive samples from API kit were tested for real-time PCR or 16S rRNA sequencing method, only B. cereus from perilla leaf, carrot, water dropwort, and sprouts showed positive results. These results indicate that selective agar and API kit detection methods might result in false positive results for some pathogens. Therefore, studies need to improve isolation or confirmation methods for such pathogens.

• Journal of fish pathology
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• v.11 no.2
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• pp.143-150
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• 1998

Characteristics and distribution of the natural commensal flora in the surrounding environment and tissues of clam in Hadong area were studied under varying conditions of growth media and incubation temperatures. Total numbers of bacteria present in intestinal tract, gill, body fluid and surrounding mud were found to be not influenced by the used BHIA, STA and SNA media. Although the growth rate of bacteria at the condition of $15^{\circ}C$ incubation temperature was slower than that of $25^{\circ}C$ and $35^{\circ}C$, it showed the highest number of total bacteria compared with other two different conditions of incubation temperature. Interestingly, the proportion of bacteria able to form colony on several selective media was higher in replica analysis from nutrient media to selective media than that in direct smearing from samples. The generic diversity of bacteria isolated from the tissues and analyzed by API 20E and API 20NE kit showed similar pattern with each other and distinct from that of environment. The distribution of bacteria in the surrounding mud or mantle fluid of clam indicated a high diversity comparable to that found for the gill or intestinal tract microflora, with Pseudomonas being the prevalent group. It implies that the tissues of clam may probide a selective habitat for a commensal microflora.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.146-149
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• 2013

Bacteria of genus Vibrio are Gram-negative, curved, halophilic, nonspore-forming bacteria, autochthonous inhabitans of the marine and estuarine environments. Some of the Vibrio species such as V. parahaemolyticus, V. vulnificus, and V. cholerae are associated with human disease. Each year many people have been suffering from food-borne disease caused by the ingestion of seafood. In this study, we have monitored antibiotic resistance of this microorganism in 6 coastal areas of West Sea by sampling shellfish monthly. Vibrio spp. were detected from 23.3% of 120 samples analyzed using TCBS agar plates as well as API 20E kit. Among 16 antibiotics tested, resistance to vancomycin and ampicillin was observed in 82.1% of the isolates, and Vibrio spp. resistant to rifampin (71.4%) and cephalothin (53.6%) were also high. Most of the isolates were sensitive to chloramphenicol (92.9%), sulfamethoxazole/trimethoprim (92.9%), and tetracycline (96.4%). About 71.4% of the isolates showed multiple drug resistance toward 3 antibiotics including vancomycin and ampicillin.

• Microbiology and Biotechnology Letters
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• v.29 no.2
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• pp.78-83
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• 2001

Phytase (myo-inositol hexakisphosphate phosphohydrolase: EC 3.1.3.8) hydrolyzes phytic acid (myo-inositol hexakisphosphate) to myo-inositol and monophosphates. In order to obtain phytase producing bacteria, many samples were collected from various soils. Among thirty-five phytase-producing strains, YH100 showed the highest phytase activity. In order to identify the selected YHlOO strain, the morphological and physiological characteristics were examined according to the method of Bergey's manual by 168 rRNA sequence, cellular fatty acids profile, O+C contents and physiological test using API 20E kit. The strain YH100 identified to be a genus of Enterobacter cloacae and was named as Enterobacter cloacae YHlOO. Optimum medium for the phytase production by the Entemhacter c!o([we YHlOO was composed of 2.0%(w/v) glucose, 1.0%(w/v) peptone, 1.0%(w/v) beef extract, 0.1 %(w/v) KCI. and 0.1 %( w/v) sodium phytate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.2
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• pp.185-190
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• 2003

The effects of pine needle extract and horseradish on the growth of Vibrio isolated from crab and flat fish were investigated. The isolated Vibrios were identified as Vibrio parahaemolyticus HY I and V. vulnificus FST I by Api 20E kit. The growth of V. parahaemolyticus HY 1, V. vulnificus FST I and V. perahaernolytich ATCC17802 were inhibited in tryptic soy broth (TSB) containing 1% pine needle ethanol extract. The growth of the Vibrios was more 2 log inhibited in TSB containing 1% pine needle extract and 1% horseradish than in TSB containing 1% horseradish alone. Viable cells of tile Vibrios were decreased more rapidly about 2~3 log in soysauce containing 1% pine needle extract and 1% of horseradish than in soysauce and in soysauce containing 1% horeseradish. Sensory quality of horseradish sauce containing 1% of pine needle extract was similar to that of horseradish sauce (p<0.05).

• Microbiology and Biotechnology Letters
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• v.34 no.2
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• pp.101-108
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• 2006

YNB54 strain which shows inhibitory activities specific to the plant pathogenic Phytophthora sp. on potato dextrose agar medium was screened among lots of strains isolated from Korean soils. To identify taxonomy of the Phytophthora specific antagonistic bacteria YNB54, 165 rDNA sequence, MIDI fatty acid composition, DNA-DNA hybridization, GC content, and commercial multitest systems such as API 20E and Biolog GN were performed. Results of commercial kits including lots of biochemical and physiological reactions showed that this strain was closely related to taxa including Enterobacter cloacae and Enterobacter cancerogenus species than other genera(Citerobacter Klebsiella, Leclercia). Also, analysis of its MIDI, G+C contents, and DNA-DNA hybridization suggests that this strain was more similiar to the Genus Enterobacter than other genera (Citerobacter Klebsiella, Leclercia). This strain was potentially identified as Enterobacter sp. by these results. But our 16S ribosomal DNA sequences (rDNA) analysis confirmed that it was more closely related to the cluster of Citerobacter freundii ATCC 29935 than any other Enterobacter species. In the absence of defined phylogenetic critia for delineating genera, the results observed with Citrobacter and Enterobacter species suggest that further studies are needed to clarify their relationships. This investigation demonstrates that YNB54 strain is genetically diverse and potentially more taxonomically complex than hitherto realized. Further study is necessary to confirm their taxonomic positions.