• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1787-1792
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• 2011

The object of this study was to compare the performance of commercial enrichment media used for Shigella spp. A total of four enrichment media, Gram negative (GN) broth, Shigella broth (SB), selenite-F (SF) broth, and selenite cystine (SC) broth, were tested. When S. sonnei was inoculated into each enrichment broth at 10 cfu/mL of concentration, the highest growth was observed in Shigella broth. Morganella spp., which was not differentiated in selective agar of Shigella spp. thus can be counted as false positive, did not grow in Shigella broth in enrichment step. When S. sonnei was artificially inoculated into pork, it was mostly recovered through an enrichment process with GN broth and SF broth. However, in the case of beef, S. sonnei was mostly recovered with GN broth but largely failed with Shigella broth. Therefore, enrichment media for Shigella spp. should be selected by considering the food matrix in order to increase the chance of isolating it from foods.

• Food Science of Animal Resources
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• v.38 no.4
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• pp.829-834
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• 2018

The objective of this study was to determine the minimum enrichment time for different types of food matrix (pork, beef, and fresh-cut lettuce) in an effort to improve Escherichia coli detection efficiency. Fresh pork (20 g), beef (20 g), and fresh-cut lettuce (20 g) were inoculated at 1, 2, and 3 Log CFU/g of Escherichia coli. Samples were enriched in filter bags for 3 or 5 h at $44.5^{\circ}C$, depending on sample type. E. coli cell counts in the samples were enriched in E. coli (EC) broth at 3 or 5 h. One milliliter of the enriched culture medium was used for DNA extraction, and PCR assays were performed using primers specific for uidA gene. To detect E. coli (uidA) in the samples, a 3-4 Log CFU/mL cell concentration was required. However, E. coli was detected at 1 Log CFU/g in fresh pork, beef, and fresh-cut lettuce after 5, 5, and 3-h enrichment, respectively. In conclusion, 5-h enrichment for fresh meats and 3-h enrichment for fresh-cut lettuce in EC broth at $44.5^{\circ}C$, and PCR analysis using uidA gene-specific primers were appropriate to detect E. coli rapidly in food samples.

• Journal of Food Hygiene and Safety
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• v.25 no.4
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• pp.320-324
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• 2010

Five different enrichment methods were studied to find an optimal method to recover Yersinia enterocolitica from swine feed samples. When the recovery of Y. enterocolitica GER-C (serotype O:3) strain was studied at 1000 CFU/g feed, phosphate-buffered saline (PBS) enrichment at $4^{\circ}C$ and PBS plus sorbitol and bile salts (PSB) enrichment at $4^{\circ}C$ and $21^{\circ}C$ were not effective (< 22%). In contrast, both irgasan-ticarcillin-potassium chlorate (ITC) and tryptic soy broth plus polymyxin B sulfate and novobiocin (TSBPN) enrichment methods showed a full recovery (100%) at 100-1000 CFU/g feed. At 10 CFU/g feed, both ITC and TSBPN methods still recovered the strain (> 50%). In recovery of ATCC 9610 (serotype O:8) strain, TSBPN method was more sensitive than any other methods (P < 0.05) at 1000 CFU/g feed. Using TSBPN method, the strain was still recovered at 100 CFU/g feed, but not at 10 CFU/g feed. With its sensitivity and relatively simple recipe, TSBPN was most desirable method to recover Y. enterocolitica from swine feed samples.

• Food Science and Preservation
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• v.23 no.6
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• pp.759-764
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• 2016

This purpose of this study was to determine the best enrichment medium for rejuvenating and recovering Salmonella placed in cold temperature prior to the employment of the gold biosensor combined with a light microscopic imaging system. A mixture of nalidixic-resistant Salmonella Typhimurium and Enteritidis were inoculated onto chicken (1,000 CFU/chicken). After cold injury at $4^{\circ}C$ for 24 hr, Salmonella on chicken was enriched for 6 hr with six non-selective media including buffered peptone water broth, lactose broth, brain heart infusion broth (BHI), universal pre-enrichment broth, nutrient broth, and tryptic soy broth, and five selective media including brilliant green broth (BG), rappaport-vassiliadis R10 broth, selenite cystine broth, selenite broth, and tetrathionate brilliant green broth (TBG) for the comparison of Salmonella growth. Various concentrations of Salmonella (10, 50, 100, 500, and 1,000 CFU/chicken) were then enriched for 6 hr in both BHI and BG media to select the best media. BHI was selected as the most effective non-selective enrichment medium, while BG was selected as the most effective selective enrichment medium. Finally, BHI medium was selected as the most efficient enrichment medium for Salmonella growth injured from cold temperature during processing or storage.

• Korean Journal of Food Science and Technology
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• v.48 no.4
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• pp.323-328
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• 2016

In this study, specific and rapid enrichment and growth conditions for the most important, classic non-O157 enterohemorrhagic Escherichia coli (EHEC) serogroups were assessed. Three enrichment broth types, namely, EC medium with MUG broth, BRILA broth, and mTSB broth with novobiocin, were compared to identify the optimum enrichment broth for EHEC isolation. Four kinds of selective media, namely, ENDO agar, Chromocult agar, TBX agar, and CHROMagar$^{TM}$ STEC medium, were compared to identify the optimum one for non-O157 EHEC isolation. The results suggested that incubation in EC medium with MUG broth at $42^{\circ}C$ for 20 h is optimum for the enrichment of non-O157 EHEC. TBX agar was identified to have the highest specificity among the tested media. Consequently, a combination of complementary selective media according to serotype must be considered for comprehensive isolation of specific EHEC.

• Journal of Food Hygiene and Safety
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• v.33 no.1
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• pp.65-70
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• 2018

Monitoring of Listeria monocytogenes, the causative agent of listeriosis, in food is inportant for public health. The Korean Food Standards Codex has adopted a 'zero-tolerance' policy for L. monocytogenes. The standard detection method of L. monocytogenes is based on enrichment. Thus, proper enrichment methods need to be instituted to ensure quality control of the detection procedures. In this study, the growth of L. monocytogenes and Listeria innocua as a mixed culture in Listeria enrichment broth (LEB) was monitored during artificial contamination of enrichment culture. We confirmed competitive growth or interspecies inhibitory activity of L. monocytogenes and L. innocua. Interspecies growth differences and the inhibitory activity of different inoculation and mixtures L. innocua against L. monocytogenes were examined. The concentration of L. monocytogenes must be 2.0 log CFU/mL or more than L. innocua to grow better than L. innocua. It is known that Listeria spp. and L. monocytogenes show growth difference during LEB, resulting in the risk of false-negative results. The inhibition of L. monocytogenes by L. innocua was always observed when present at lower concentrations. However, it was confirmed that L. innocua suppressed when L. monocytogenes was present at a higher concentration. Therefore if a mixture of Listeria spp. is present, detecting L. monocytogenes is difficult. Thus, a new enrichment broth to improve the detection rate of L. monocytogenes is needed.

• Journal of Food Hygiene and Safety
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• v.35 no.4
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• pp.334-340
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• 2020

In this study we developed an enrichment medium and lysis buffers to detect Listeria monocytogenes in meat and processed meat products under various lysis conditions. The enrichment efficiency of L. monocytogenes medium listed in the Food Standards was compared, and thus, Listeria Enrichment Broth (LEB) was modified by adding supplements such as carbon source and minerals. The lysis buffers were developed to extract L. monocytogenes DNA quickly and efficiently under various lysis conditions. L. monocytogenes was most rapidly grown in LEB containing 0.1% pyruvate and 0.1% ferric citrate. A lysis buffer mixed with 0.5% or 1% N-lauroylasrcosine sodium salt, 0.5 N NaOH and 0.5 M EDTA for 30 min at room temperature was found to be the best in terms of DNA purity and yield. These results indicate that developed enrichment medium and lysis buffer can be used to detect L. monocytogenes in meat and processed meat products rapidly and efficiently.

• Microbiology and Biotechnology Letters
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• v.24 no.6
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• pp.647-651
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• 1996

The development of an enrichment method for the rapid and effective identification of Salmonella spp. in sewage or food was studied. As a growth factor for Salmonella, 10 mM cyclic adenosine monophosphate (cAMP) in trypticase soy broth with 0.6% yeast extract (TSBYE) increased cell number five-folds and 0.6% yeast extract in selenite broth increased cell number ten-folds of control. Bile salts in selenite broth was tested for the selection of S. enteritidis in a mixture with Staphylococcus aureus, Pseudomonas aeruginosa, Lactobacillus plantarum and Escherichia coli. The latter four strains were effectively inhibited at 0.1% bile salt. A two-step culture method was used to enrich Salmonella spp.; a primary-enrichment and secondary- enrichment culture. At a primary-enrichment step, selenite broth with 0.6% yeast extract and 10 mM cAMP was used, and at a secondary-enrichment step, 0.1% bile salt was additionally used. Culture times of a primary- enrichment and a secondary-enrichment step were 8 hr and 6 hr, respectively. In this procedure, cell number increased from 10$^{0.3}$ to 10$^{8.5}$ with inhibition of other strains within 14 hr. In the case of an initial cell concentrarion as low as 10$^{-2}$ cfu/ml, a cell number increased to 10$^{7}$ cfu/ml by using a 10 hr primary-enrichment and 6 hr secondary-enrichment procedure.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.1
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• pp.7-12
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• 2004

This study investigated the possibility of salinity acclimation of freshwater rotifers (Brachionus calyciflorus) as live food for sweetfish (Plecoglossus altivelis) larvae, and also examined the optimal salinity for the growth of sweetfish. Freshwater rotifers cultured in 0 and 4 PSU and seawater rotifers (B. rotundiformis) cultured in 33 PSU were supplied to the larvae with four kinds of enrichment material (condensed freshwater Chlorella, $\omega-yeast,$ baker's yeast, Super Selco) and larval growth at 4 PSU was examined. Growth of the freshwater rotifers positively increased from 0 PSU to 6 PSU, but decreased when over 8 PSU was reached. Growth and survival of the sweet fish larvae reared in 0 PSU were significantly lower than those reared in either 4 PSU or 33 PSU. This indicated that the freshwater rotifers (B. calyciflorus) could be used as live food for sweetfish larvae reared in 4 PSU. The body weight of sweetfish larvae fed on freshwater rotifers enriched with Super Selco was the highest at 0.163 mg, but there was no significant difference in survival and body length of the fish fed with the other enrichment materials. The content of n-3 HUFA of the sweetfish larvae fed on the freshwater rotifers enriched with Super Selco and the condensed freshwater Chlorella was higher than that enriched with $\omega-yeast$ and baker's yeast. These results indicated that B. calyciflorus cultured with the condensed freshwater Chlorella could be used for the sweetfish larvae without enrichment, and the most efficient enrichment material for B. calyciflorus is Super Selco.

• Korean Journal of Microbiology
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• v.47 no.1
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• pp.87-91
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• 2011

The aim of this study was to compare the performance of conventional culture and real-time PCR for detection of Cronobacter spp. in powdered foods. Infant formula, baby food and Misugaru inoculated with Cronobacter were enriched in distilled water as first enrichment step, followed by incubating in Enterobacteriaceae enrichment (EE) broth as second enrichment step. A loopful of enriched sample was streaked onto Druggan-Forsythe-Iversen agar, followed by incubating at $37^{\circ}C$ for 24 h. One milliliter of the enriched distilled water and EE broth were used in real-time PCR assay. No statistical differences were observed in the number of positive samples between culture method and real-time PCR (p>0.05) in all types of food samples. The number of positives of real-time PCR was higher in the first enrichment media (distilled water) than the second enrichment media (EE broth), though there was no significant difference (p>0.05). It appears that some components of the second enrichment broth, EE broth, inhibit the reaction of real-time PCR. These results show that real-time PCR using a single enrichment with distilled water could be useful as an effective screening method for detection of Cronobacter while saving much time and labor compared to conventional culture method.