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Journal articles on the topic 'Selective enrichment'

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Published: 4 June 2021

Last updated: 20 February 2023

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1

Stewart, Fiona, Erbay Yigit, and George R. Feehery. "Selective Enrichment of Microbial DNA." Genetic Engineering & Biotechnology News 34, no. 3 (February 2014): 22–23. http://dx.doi.org/10.1089/gen.34.03.12.

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2

de Pater, Imke. "Selective enrichment of volatiles confirmed." Nature Astronomy 2, no. 5 (April 23, 2018): 364–65. http://dx.doi.org/10.1038/s41550-018-0457-5.

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3

ALLEN, GERALDINE, VERNEAL R. BRUCE, WALLACE H. ANDREWS, FELICIA B. SATCHELL, and PATRICIA STEPHENSON. "Recovery of Salmonella from Frozen Shrimp: Evaluation of Short-Term Selective Enrichment, Selective Media, Postenrichment, and a Rapid Immunodiffusion Method." Journal of Food Protection 54, no. 1 (January 1, 1991): 22–27. http://dx.doi.org/10.4315/0362-028x-54.1.22.

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Frozen shrimp was used as a high-moisture food matrix to evaluate the effect of the following conditions and media on the recovery of Salmonella: comparative efficiency of 6 and 24 h selective enrichment incubation periods; efficiency of Rappaport-Vassiliadis (RV) medium relative to selenite cystine (SC) and tetrathionate (TT) selective enrichment broths; need for postenrichment; and reliability of the immunodiffusion method (Salmonella 1–2 TEST) as a rapid screening procedure. From a total of 244 Salmonella-positive, samples, recoveries at 6 h for selective enrichments SC, TT, RV(1) receiving 1 ml of inoculum, and RV(2) receiving 0.1 ml of inoculum, were 147, 149, 200, and 169, respectively; at 24 h, recoveries were 148, 142, 193, and 205, respectively. As a selective enrichment, RV medium was generally more productive than either SC or TT broths. Postenrichment reduced method sensitivity. Test kit reactions were read independently by three analysts to evaluate the immunodiffusion method. Examination of 200 shrimp samples by standard cultural and 1–2 TEST methods detected 52.5–57% and 56.5–60.5% positive samples, respectively.

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4

IKEGUCHI, Yoshihiko, and Hiroshi NAKAMURA. "Selective Enrichment of Phospholipids by Titania." Analytical Sciences 16, no. 5 (2000): 541–43. http://dx.doi.org/10.2116/analsci.16.541.

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5

KEYS, ASHLEY L., ANTHONY D. HITCHINS, and R. DERIKE SMILEY. "Contribution of Selective Conditions to Microbial Competition in Four Listeria Selective Enrichment Formulations." Journal of Food Protection 79, no. 11 (November 1, 2016): 1904–10. http://dx.doi.org/10.4315/0362-028x.jfp-16-216.

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ABSTRACT Microbial competition during selective enrichment negatively affects Listeria monocytogenes populations and may hinder the subsequent detection or recovery of this organism. Competition assays among 10 selected strains of Listeria and Citrobacter braakii were performed in buffered Listeria enrichment broth, 3-(N-morpholino)propanesulfonic acid–buffered Listeria enrichment broth, University of Vermont medium–modified Listeria enrichment broth, and Fraser broth. The individual contributions of each selective agent in these media were also assessed, as well as the contribution of incubation temperature. Acriflavine hydrochloride and sodium nalidixate were ineffective at preventing the overgrowth of C. braakii; this resulted in substantially lower populations of Listeria than when the competitor was absent. At the higher levels, both of these selective agents were detrimental to Listeria populations. The highest enrichment populations of Listeria were observed when either NaCl or LiCl was present. In the absence of selective agents, the final populations of Listeria following competitive growth with C. braakii were not substantially affected by temperature; however, in the presence of selective agents, the Listeria populations were statistically higher at the higher incubation temperature. There are a limited number of selective agents available for use in Listeria-specific enrichment media, resulting in formulations that are only somewhat selective for this species. The optimization of current formulations may help researchers to improve Listeria recovery, particularly from products with a high microbial load. The understanding of the behavior and interactions between target and nontarget microorganisms in the presence of these available selective agents is a necessary step in the optimization of Listeria selective enrichment formulations.

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6

Riley, T. V., J. S. Brazier, Hamimah Hassan, Kathleen Williams, and K. D. Phillips. "Comparison of alcohol shock enrichment and selective enrichment for the isolation ofClostridium difficile." Epidemiology and Infection 99, no. 2 (October 1987): 355–59. http://dx.doi.org/10.1017/s0950268800067832.

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SUMMARYTwo enrichment methods were compared for their ability to recoverClostridium difficilefrom stool samples. One method used selective enrichment in an antibiotic-containing broth followed by detection with a latex particle agglutination (LPA) reagent. The other used enrichment in a non-selective broth following treatment of the specimen with alcohol. With clinical specimens enrichment culture was significantly more successful at detectingC. difficilethan direct plating. Alcohol shock enrichment was twice as effective as direct culture, while selective broth enrichment was three times more effective. The use of LPA for screening selective enrichment broths forC. difficileshould prove a cost-effective measure as only positive broths (about 20%) require subculture for confirmation.

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7

SARLIN, LAURA L., ERIC T. BARNHART, RANDLE W. MOORE, DONALD E. CORRIER, LARRY H. STANKER, and BILLY M. HARGIS. "Comparison of Enrichment Methods for Recovery and Chick Infectivity of Chlorine-lnjured Salmonella enteritidis." Journal of Food Protection 61, no. 11 (November 1, 1998): 1504–6. http://dx.doi.org/10.4315/0362-028x-61.11.1504.

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In recent years, several preenrichment media have been shown to be effective for use in the recovery of sublethally injured Salmonella organisms. Selective enrichment without preenrichment has resulted in a lower recovery of organisms, particularly with regard to injured or stressed salmonellae. The present experiments compared the ability of nonselective preenrichment followed by selective enrichment or direct selective enrichment alone to recover chlorine-injured Salmonella organisms. Additionally, the Salmonella detection limits of the two enrichment methods were compared with minimal infectious dose in neonatal chicks. In three experiments, Salmonella enteritidis cells were exposed to chlorine for specific times and subsequently cultured by using preenrichment followed by selective enrichment or selective enrichment alone. Simultaneously, neonatal chicks were orally challenged with S. enteritidis cells from each exposure time to chlorine. The results indicated a marginal, but significantly (P < 0.05) higher level of recovery of sublethally injured salmonellae by using nonselective preenrichment followed by selective enrichment, as compared to selective enrichment alone. Interestingly, both culture methods were capable of detecting injured S. enteritidis cells at levels incapable of infecting neonatal chicks.

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8

Kumar, Rakesh, Poothuvallil K. Surendran, and Nirmala Thampuran. "Evaluation of Culture Media for Selective Enrichment and Isolation of Salmonella in Seafood." Journal of AOAC INTERNATIONAL 93, no. 5 (September 1, 2010): 1468–71. http://dx.doi.org/10.1093/jaoac/93.5.1468.

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Abstract Seafood, including fish, shrimp, clam, crab, mussel, oyster, lobster, squid, octopus, and cuttlefish samples, was used to compare the recovery of Salmonella serovars by different selective enrichment and isolation media. The samples were selectively enriched in Rappaport-Vassiliadis (RV) broth and tetrathionate broth (TT), followed by selective isolation on Hektoen enteric (HE) agar, xylose lysine desoxycholate (XLD) agar, bismuth sulfite (BS) agar, and Brilliant Green (BG) agar media. Of 443 seafood samples analyzed, 108 were found to be contaminated with Salmonella. The role of selective enrichment in Salmonella spp. recovery with RV medium was distinctly high (70%) compared to TT broth (30%). The selective enrichment in RV broth followed by selective isolation on XLD, HE, BS, and BG agar recovered Salmonella at levels of 56, 41, 28, and 16%, respectively. Similarly, after enrichment in TT broth, XLD and HE agars recovered 27 and 23 respectively. The recovery of Salmonella with enrichment in TT followed by isolation on BS and BG was abysmally low at 4.6 and 5, respectively. There was no significant difference (P > 0.05) in the recovery of Salmonella using the combinations of XLD and HE media with selective enrichment in RV broth. However, performance difference (P <0.05) was observed in the recovery when BS and BG with RV, and XLD, HE, BS, and BG agars with TT broth were used. The present study showed that the combination of RV with XLD was the most efficient media for isolation of Salmonella from seafood when compared to other isolation media combinations.

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9

Zhao, Xu, Wuhui Jiang, Long Yu, Lijuan Zou, Xiuling Li, and Xinmiao Liang. "Selective Enrichment of Glycopeptides Using Aluminum Oxide." Acta Chimica Sinica 71, no. 3 (2013): 343. http://dx.doi.org/10.6023/a12121103.

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10

Son, Moon, Eric Kolvek, Taeyoung Kim, Wulin Yang, Johannes S. Vrouwenvelder, Christopher A. Gorski, and Bruce E. Logan. "Stepwise ammonium enrichment using selective battery electrodes." Environmental Science: Water Research & Technology 6, no. 6 (2020): 1649–57. http://dx.doi.org/10.1039/d0ew00010h.

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11

Hilyard, Edward J., Joanne M. Jones-Meehan, Barry J. Spargo, and Russell T. Hill. "Enrichment, Isolation, and Phylogenetic Identification of Polycyclic Aromatic Hydrocarbon-Degrading Bacteria from Elizabeth River Sediments†." Applied and Environmental Microbiology 74, no. 4 (December 21, 2007): 1176–82. http://dx.doi.org/10.1128/aem.01518-07.

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ABSTRACT The diversity of indigenous bacteria in sediments from several sites in the Elizabeth River (Virginia) able to degrade multiple polycyclic aromatic hydrocarbons (PAHs) was investigated by the use of classical selective enrichment and molecular analyses. Enrichment cultures containing naphthalene, phenanthrene, fluoranthene, or pyrene as a sole carbon and energy source were monitored by denaturing gradient gel electrophoresis (DGGE) to detect changes in the bacterial-community profile during enrichment and to determine whether the representative strains present were successfully cultured. The DGGE profiles of the final enrichments grown solely on naphthalene and pyrene showed no clear relationship with the site from which the inoculum was obtained. The enrichments grown solely on pyrene for two sample sites had >80% similarity, which suggests that common pyrene-degrading strains may be present in these sediments. The final enrichments grown on fluoranthene and phenanthrene remained diverse by site, suggesting that these strains may be influenced by environmental conditions. One hundred and one isolates were obtained, comprising representatives of the actinomycetes and alpha-, beta-, and gammaproteobacteria, including seven novel isolates with 16S rRNA gene sequences less than 98% similar to known strains. The ability to degrade multiple PAHs was demonstrated by mineralization of 14C-labeled substrate and growth in pure culture. This supports our hypothesis that a high diversity of bacterial strains with the ability to degrade multiple PAHs can be confirmed by the combined use of classical selective enrichment and molecular analyses. This large collection of diverse PAH-degrading strains provides a valuable resource for studies on mechanisms of PAH degradation and bioremediation.

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12

HITCHINS, ANTHONY D., and R. E. DUVALL. "Feasibility of a Defined Microflora Challenge Method for Evaluating the Efficacy of Foodborne Listeria monocytogenes Selective Enrichments." Journal of Food Protection 63, no. 8 (August 1, 2000): 1064–70. http://dx.doi.org/10.4315/0362-028x-63.8.1064.

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Comparison of isolation methods for microbial pathogens is complicated by the variable interference caused by the competitive microflora present in test samples such as foods. In principle, using measured amounts of a standard competitor in a defined surrogate food matrix might control the effect of variable interference. This possibility was investigated using Listeria monocytogenes and enrichment broths belonging to the acriflavine-nalidixate selective agent class. Triplicate test sample sets were prepared. Each set consisted of suspensions of variable levels of the standard competitor, Enterococcus faecium strain 111 (≈10 to 109 CFU/25 g), mixed with a low constant level (10 to 100 CFU/25 g) of L. monocytogenes. These test samples were enriched at 30°C for 48 h in different selective media and streaked onto selective isolation agars. The input CFU ratio (E. faecium/L. monocytogenes) that permitted a 50% end point L. monocytogenes recovery was 2.2 × 106 or higher for the Food and Drug Administration one-step enrichments and 0.8 × 106 for the International Standards Organization (ISO) two-step enrichment. These and other results show that this evaluation method is feasible with this class of enrichments. Interestingly, L. monocytogenes could be detected in enrichment cultures at high-input E. faecium/L. monocytogenes ratios even when the enriched samples were plated onto nonselective media. The pinpoint colonies of L. monocytogenes embedded in a confluent lawn of E. faecium 111 were detectable by their contrasting coloration in Henry obliquely transmitted illumination.

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13

Oliveira, S. D., C. R. Rodenbusch, M. C. Cé, S. L. S. Rocha, and C. W. Canal. "Evaluation of selective and non-selective enrichment PCR procedures for Salmonella detection." Letters in Applied Microbiology 36, no. 4 (March 14, 2003): 217–21. http://dx.doi.org/10.1046/j.1472-765x.2003.01294.x.

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14

CHEN, Cheng, Hongjian KANG, Xiaofei ZHANG, Xiuling LI, and Xinmiao LIANG. "Biomimetic polymer material for glycopeptide high selective enrichment." Chinese Journal of Chromatography 37, no. 8 (2019): 845. http://dx.doi.org/10.3724/sp.j.1123.2019.03028.

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15

Wei, Xiaona, and Xin Shi. "Mesoporous Zirconium Phenylphosphonates for Selective Enrichment of Phosphopeptides." Journal of Physical Chemistry C 118, no. 8 (February 17, 2014): 4213–21. http://dx.doi.org/10.1021/jp411346k.

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16

Güzel, Yüksel, Shah Hussain, Matthias Rainer, and Günther K. Bonn. "Highly selective enrichment of phosphopeptides using aluminum silicate." Anal. Methods 6, no. 22 (2014): 9160–67. http://dx.doi.org/10.1039/c4ay01918k.

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17

Lu, Zhenda, Jicheng Duan, Le He, Yongxing Hu, and Yadong Yin. "Mesoporous TiO2Nanocrystal Clusters for Selective Enrichment of Phosphopeptides." Analytical Chemistry 82, no. 17 (September 2010): 7249–58. http://dx.doi.org/10.1021/ac1011206.

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18

Peltosaari, Olli, Pekka Tanskanen, Sofia Hautala, Eetu-Pekka Heikkinen, and Timo Fabritius. "Mechanical enrichment of converted spodumene by selective sieving." Minerals Engineering 98 (November 2016): 30–39. http://dx.doi.org/10.1016/j.mineng.2016.07.010.

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19

Wu, Xiaojian, Jie Pan, Meng Li, Yao Li, Mark Bartlam, and Yingying Wang. "Selective enrichment of bacterial pathogens by microplastic biofilm." Water Research 165 (November 2019): 114979. http://dx.doi.org/10.1016/j.watres.2019.114979.

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20

Ly, Linda, and Valerie C. Wasinger. "Peptide enrichment and protein fractionation using selective electrophoresis." PROTEOMICS 8, no. 20 (September 22, 2008): 4197–208. http://dx.doi.org/10.1002/pmic.200701088.

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21

Li, Xiao-Shui, Xi Chen, Huan Sun, Bi-Feng Yuan, and Yu-Qi Feng. "Perovskite for the highly selective enrichment of phosphopeptides." Journal of Chromatography A 1376 (January 2015): 143–48. http://dx.doi.org/10.1016/j.chroma.2014.12.036.

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22

Setaro, Antonio, Pascal Bluemmel, Marcus Ulf Witt, Rohit Narula, and Stephanie Reich. "Carbon nanotube chirality enrichment through chirality-selective precipitation." physica status solidi (b) 253, no. 12 (November 10, 2016): 2380–84. http://dx.doi.org/10.1002/pssb.201600642.

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23

TORTORELLO, M. L., K. F. REINEKE, D. S. STEWART, and R. B. RAYBOURNE. "Comparison of Methods for Determining the Presence of Escherichia coli O157:H7 in Apple Juice." Journal of Food Protection 61, no. 11 (November 1, 1998): 1425–30. http://dx.doi.org/10.4315/0362-028x-61.11.1425.

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Six methods were compared for detection of three strains of Escherichia coli O157:H7 in enrichments of inoculated apple juice. Juice was inoculated at levels varying from 0.1 to 100 CFU/ml and centrifuged after ovemight storage at 4°C, and pellets were incubated at 37°C in nonselective enrichment broth. At hourly intervals between 5 and 10 h and at 24 h, the enrichments were tested for E. coli O157:H7 by direct fluorescent antibody (DFA), antibody-direct epifluorescent filter technique (Ab-DEFT), direct selective plating on sorbitol MacConkey agar (SMA), immunomagnetic separation coupled to either selective plating (IMS-SMA) or the polymerase chain reaction (IMS-PCR), and flow cytometry (FC). The most consistent detection of 0.1 CFU/ml of the slowest growing strain of the pathogen was provided by the IMS-SMA and IMS-PCR after 8 h of enrichment. The time required for detection at the level of 0.1 CFU/ml for each assay was Ab-DEFT, 11 h; IMS-PCR, 16 h; FC, 24 h; IMS-SMA, 32 h; and SMA, 48 h. Absolute detection limits (without enrichment) were: IMS-PCR, 103 CFU/ml; Ab-DEFT and IMS-SMA, 104 CFU/ml; SMA, 105 CFU/ml; and DFA, 106 CFU/ml. Recovery of the pathogen (10 CFU/ml) in apple juice after 28 days of 4°C storage was possible by means of an 8-h enrichment and Ab-DEFT, IMS-PCR, or IMS-SMA.

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24

Parsons, Cameron, Midya Jahanafroozi, and Sophia Kathariou. "Requirement of lmo1930, a Gene in the Menaquinone Biosynthesis Operon, for Esculin Hydrolysis and Lithium Chloride Tolerance in Listeria monocytogenes." Microorganisms 7, no. 11 (November 8, 2019): 539. http://dx.doi.org/10.3390/microorganisms7110539.

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Listeria monocytogenes is a foodborne pathogen that is widely distributed in nature, having been isolated from a variety of sources such as soil, water, plant matter, and animals. In addition, L. monocytogenes is often detected in the regular sampling of food and food processing environments. The most common method for detecting L. monocytogenes is the use of selective enrichments. Both lithium chloride and esculin, in combination with ferric ammonium citrate, are utilized in several of the most commonly-employed selective enrichment schemes for L. monocytogenes. Here we report that transposon-based inactivation of lmo1930, one of the genes in the menaquinone biosynthesis operon, via transposon mutagenesis severely impaired the ability of L. monocytogenes to grow in the presence of lithium chloride or hydrolyze esculin, and conferred reduced growth and colony size. All phenotypes were restored upon genetic complementation. Thus, strains of L. monocytogenes with mutations leading to inactivation of lmo1930 may evade many commonly-used selective enrichment protocols employed in the detection of L. monocytogenes.

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25

Amerkhanova, Sh K., R. M. Shlyapov, A. S. Uali, D. S. Belgibayeva, and O. Ye Kaliyev. "Development of enrichment reagent regime of Py-Cu-Zn ore using collectors’ mixtures." BULLETIN of the L.N. Gumilyov Eurasian National University. Chemistry. Geography. Ecology Series 135, no. 2 (2021): 32–40. http://dx.doi.org/10.32523/2616-6771-2021-135-2-32-40.

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The article presents results of flotation enrichment of pyrite-copper-zinc ore in a selective mode. It allows predicting the choice of technology for enrichment of non-ferrous metal ores based on mathematical models describing the influence of hydrodynamic and reagent modes on the flotation parameters of the ore under study. The use of a mixture of flotation reagents excludes the use of special foaming agents in the process of selective flotation enrichment because the function of foaming agents and collectors is performed by flotation reagents. At the same time, an increase in the yield of the concentrate and the degree of metal extraction into the concentrate is achieved, and an increase in the selectivity of metal extraction and the degree of flotation enrichment of polymetallic ore. As a result of the processing and analysis of data on the flotation collective-selective enrichment of pyrite-copper-zinc ore, there have been developed recommendations for the technological evaluation of the choice of a selective reagent mode of flotation enrichment of ores.

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26

SILK, TODD M., TATIANA M. T. ROTH, and C. W. DONNELLY. "Comparison of Growth Kinetics for Healthy and Heat-Injured Listeria monocytogenes in Eight Enrichment Broths." Journal of Food Protection 65, no. 8 (August 1, 2002): 1333–37. http://dx.doi.org/10.4315/0362-028x-65.8.1333.

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Detection of Listeria in food products is often limited by performance of enrichment media used to support growth of Listeria to detectable levels. In this study, growth curves were generated using healthy and heat-injured Listeria monocytogenes strain F5069 in three nonselective and five selective enrichment broths. Nonselective enrichment media included the current Food and Drug Administration Bacteriological Analytical Manual Listeria enrichment broth base (BAM), Listeria repair broth (LRB), and Trypticase soy broth. Selective enrichment media included BAM with selective agents and LRB with selective agents, BCM L. monocytogenes preenrichment broth, Fraser broth, and UVM-modified Listeria enrichment broth. The Gompertz equation was used to model the growth of L. monocytogenes. Gompertz parameters were used to calculate exponential growth rate, lag-phase duration (LPD), generation time, maximum population density (MPD), and time required for repair of injured cells. Statistical differences (P < 0.05) in broth performance were noted for LPD and MPD when healthy and injured cells were inoculated into the broths. With the exception of Fraser broth, there were no significant differences in the time required for the repair of injured cells. Results indicate that the distinction between selective and nonselective broths in their ability to grow healthy Listeria and to repair sublethally injured cells is not solely an elementary issue of presence or absence of selective agents.

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27

BAILEY, J. S., D. L. FLETCHER, and N. A. COX. "Effect of Enrichment Media and Sampling Protocol on Recovery of Listeria monocytogenes." Journal of Food Protection 53, no. 6 (June 1, 1990): 505–7. http://dx.doi.org/10.4315/0362-028x-53.6.505.

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These studies examined the differences in recovery of Listeria monocytogenes from pure culture and in the populations of mixed aerobic microflora from chicken and Brie cheese incubated in University of Vermont (UVM) and Listeria enrichment broth (LEB) enrichment broths for different times and conditions. No significant differences were observed in levels of L. monocytogenes from pure cultures in UVM or LEB on any sampling day. No differences were observed in the levels of mixed microflora from Brie cheese in either UVM or LEB, but from chicken rinse the level of mixed flora competitors was significantly higher on all sampling days in LEB as compared to UVM. No differences were observed between a single enrichment in UVM or LEB for 2 d and a transfer to a secondary enrichment tube after 1 d. Overall, the level of mixed microflora capable of growing in enrichment broths was greater from chicken rinse than from Brie cheese. The ratio of L. monocytogenes to mixed microflora which survived the selective enrichments was most favorable for recovery of L. monocytogenes after 2 d of enrichment.

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28

JIANG, G. C., DONG-HYUN KANG, and DANIEL Y. C. FUNG. "Enrichment Procedures and Plating Media for Isolation of Yersinia enterocolitica†." Journal of Food Protection 63, no. 11 (November 1, 2000): 1483–86. http://dx.doi.org/10.4315/0362-028x-63.11.1483.

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A shortened enrichment procedure (25°C for 24 h) was compared with cold enrichment procedures (4°C for 1 to 3 weeks) and direct plating for isolation of Yersinia enterocolitica from commercial ground meat samples. The combined data of all recovery procedures showed that this organism was isolated from 34% of the ground beef samples. The highest isolation rate was 32% for the 4°C/3-week enrichment, followed by 28% for the 4°C/2-week enrichment, 26% for the 25°C/24-h enrichment, 22% for the 4°C/1-week enrichment, and 10% for direct plating. No significant differences (P > 0.05) in isolation rate occurred between the 4°C/3-week, 4°C/2-week, 25°C/24-h, and 4°C/1-week enrichments. The combined data of all recovery procedures showed that Y. enterocolitica was isolated from 64% of ground pork samples. The highest isolation rate was 48% for the 4°C/3-week enrichment, followed by 40% for the 25°C/24-h enrichment, 34% for the 4°C/2-week enrichment, 24% for the 4°C/1-week enrichment, and 24% for direct plating. No significant differences (P > 0.05) in isolation rate occurred between the 4°C/3-week, 25°C/24-h, and 4°C/2-week enrichments. During the plating phase of the experiment, the efficiency of a dye-containing, Yersinia-selective medium (KV202) was compared with that of a commercially available cefsulodin-irgasan-novobiocin medium. Recovery rates were similar for both media. However, KV202 agar differentiated Y. enterocolitica from such contaminating bacteria as Enterobacter, Serratia, and Salmonella by colony morphologic characteristics and color.

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29

Duvall, Robert E., Marjut Eklund, Tony T. Tran, and Anthony D. Hitchins. "Improved DNA Probe Detection of Listeria monocytogenes in Enrichment Culture After Physical-Chemical Fractionation." Journal of AOAC INTERNATIONAL 89, no. 1 (January 1, 2006): 172–79. http://dx.doi.org/10.1093/jaoac/89.1.172.

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Abstract Bacterial detection in foods by nucleic acid probes is limited by microflora competition during selective enrichment. Probe target concentration by extraction and fractionation of enrichments may diminish this limitation. The 1-h AccuProbe chemiluminescent culture identification test for Listeria monocytogenes was used as a model. Its high detection threshold provides a stringent challenge for evaluating enrichmentwork-up protocols. Detection of L. monocytogenes, at 14 colony-forming units/g food,was not consistently possible in 48 h enrichment cultures usingAccuProbe. Concentration by cell sedimentationwas occasionally helpful but the volume of co-sedimented food limited concentration to about 10-fold. To improve concentration, enrichment sedimentswere sonicated or enzymatically lysed to release the probe's target, r-RNA. The RNAwas separated from non-RNA material by extraction with phenol and precipitation with ethanol. Enrichments (250 mL) were concentrated 2500-fold, and the limitation was food RNA volume. A strongly competitive Enterococcus faecium food isolate was used to demonstrate the effect of artificial competition on the kit's ability to detect L. monocytogenes in enrichments. High competitor concentrations repressed the level of the target below the detection threshold, but concentration of r-RNA enabled detection of L. monocytogenes. The effectiveness of this enrichment sample work-up was demonstrated with naturally contaminated hummus.

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30

Hughes, Denise, Angela E. Dailianis, Louise Hill, Michael S. Curiale, Vidhya Gangar, D. Arnold, C. Barrat, et al. "Salmonella in Foods: New Enrichment Procedure for TECRA Salmonella Visual Immunoassay Using a Single RV(R10) Only, TT Only, or Dual RV(R10) and TT Selective Enrichment Broths (AOAC Official Method 998.09): Collaborative Study." Journal of AOAC INTERNATIONAL 86, no. 4 (July 1, 2003): 775–90. http://dx.doi.org/10.1093/jaoac/86.4.775.

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Abstract A collaborative study was conducted to compare a new enrichment procedure for the TECRA® Salmonella Visual Immunoassay (TSVIA) with the reference method given in the U.S. Food and Drug Administration's Bacteriological Analytical Manual (7th Ed.). Three food types (milk powder, pepper, and soy flour) were analyzed in Australia and 3 food types (milk chocolate, dried egg, and raw turkey) were analyzed in the United States. Thirty-eight collaborators participated in the study. The TECRA method was evaluated using both Rappaport-Vassiliadis R10 (RV(R10)) and tetrathionate (TT) broths for selective enrichment. M broth cultures arising from each of the 2 selective enrichment broths were tested in the TSVIA using 2 individual wells, one for each selective broth, and a single well to test the pooled selective enrichment broths. The results for the pooled enrichment broths were reported elsewhere. This study presents the results for the use of single enrichment broths, i.e., RV(R10) only or TT only, with the TSVIA. No significant differences (p > 0.05) were observed for the pairwise comparison of the proportion of positive samples for either RV(R10) or TT used as a single enrichment broth for the TSVIA with that for the reference method.

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Bruhn, Jesper Bartholin, Birte Fonnesbech Vogel, and Lone Gram. "Bias in the Listeria monocytogenes Enrichment Procedure: Lineage 2 Strains Outcompete Lineage 1 Strains in University of Vermont Selective Enrichments." Applied and Environmental Microbiology 71, no. 2 (February 2005): 961–67. http://dx.doi.org/10.1128/aem.71.2.961-967.2005.

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ABSTRACT Listeria monocytogenes can be isolated from a range of food products and may cause food-borne outbreaks or sporadic cases of listeriosis. L. monocytogenes is divided into three genetic lineages and 13 serotypes. Strains of three serotypes (1/2a, 1/2b, and 4b) are associated with most human cases of listeriosis. Of these, strains of serotypes 1/2b and 4b belong to lineage 1, whereas strains of serotype 1/2a and many other strains isolated from foods belong to lineage 2. L. monocytogenes is isolated from foods by selective enrichment procedures and from patients by nonselective methods. The aim of the present study was to investigate if the selective enrichment procedure results in a true representation of the subtypes of L. monocytogenes present in a sample. Eight L. monocytogenes strains (four lineage 1 strains and four lineage 2 strains) and one Listeria innocua strain grew with identical growth rates in the nonselective medium brain heart infusion (BHI), but differed in their growth rate in the selective medium University of Vermont medium I (UVM I). When coinoculated in UVM I, some strains completely outgrew other strains. This outcome was dependent on the lineage of L. monocytogenes rather than the individual growth rate of the strains. When inoculated at identical cell densities in UVM I, L. innocua outcompeted L. monocytogenes lineage 1 strains but not lineage 2 strains. In addition, lineage 2 L. monocytogenes strains outcompeted lineage 1 L. monocytogenes strains in all combinations tested, indicating a bias in strains selected by the enrichment procedures. Bias also occurred when coinoculating two lineage 2 or lineage 1 strains; however, it did not appear to correlate with origin (clinical versus food). Identical coinoculation experiments in BHI suggested that the selective compounds in UVM I and II influenced this bias. The results of the present study demonstrate that the selective procedures used for isolation of L. monocytogenes may not allow a true representation of the types present in foods. Our results could have a significant impact on epidemiological studies, as lineage 1 strains, which are often isolated from clinical cases of listeriosis, may be suppressed during enrichment by other L. monocytogenes lineages present in a food sample.

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Sunarno, Sunarno, Novi Amalia, Sundari Nursofiah, and Tati Febrianti. "PENGGUNAAN ENRICHMENT-SELECTIVE MEDIUM UNTUK MENINGKATKAN SENSITIFITAS PEMERIKSAAN LABORATORIUM DIFTERI." Sel Jurnal Penelitian Kesehatan 7, no. 1 (July 31, 2020): 33–40. http://dx.doi.org/10.22435/sel.v7i1.3555.

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Konfirmasi laboratorium kasus difteri dilakukan dengan isolasi dan tes toksigenisitas bakteri penyebab difteri menggunakan metode konvensional berbasis kultur. Metode konvensional memiliki keterbatasan dalam hal sensitivitas pemeriksaan. Penelitian ini bertujuan untuk menguji penggunaan darah domba + telurit sebagai enrichment-selective medium untuk meningkatkan sensitivitas pemeriksaan laboratorium difteri dengan metode konvensional. Sebanyak 18 spesimen klinis (swab tenggorok) penderita difteri digunakan sebagai sampel penelitian. Swab tenggorok tersebut sebelumnya telah digunakan untuk pemeriksaan Polymerase Chain Reaction (PCR) sehingga proses ekstraksi DNA menyebabkan jumlah sel bakteri yang tertinggal menjadi sangat terbatas. Sel bakteri tersebut ditumbuhkan menggunakan 2 cara yang berbeda, yaitu inokulasi langsung dan inokulasi yang didahului dengan penggunaan enrichment-selective medium. Hasil identifikasi bakteri penyebab difteri dibandingkan antara keduanya. Hasil penelitian menunjukkan bahwa inokulasi secara langsung hanya berhasil mengisolasi dan mengidentifikasi bakteri penyebab difteri (Corynebacterium diphtheriae) pada 3 dari 18 sampel yang diperiksa. Sebaliknya dengan penggunaan enrichment-selective medium, bakteri penyebab difteri berhasil diisolasi dan diidentifikasi pada 9 dari 18 sampel yang diperiksa. Oleh karena itu, disimpulkan bahwa enrichment-selective medium (darah domba + telurit) dapat digunakan untuk meningkatkan sensitivitas pemeriksaan laboratorium difteri. Laboratory confirmation for diphtheria cases are performed by using conventional culture-based method for isolation/identification and toxigenicity of the bacteria causing diphtheria. This method has limitation in its sensitivity. This study aimed to examine the sensitivity of sheep blood + tellurite as the enrichment selective medium to improve the sensitivity of the conventional method. The samples were 18 clinical specimens (throat swabs) obtained from diphtheria patient, which had been used for Polymerase Chain Reaction (PCR) assay, therefore the DNA extraction process caused the number of bacteria cells to be very limited. The samples were cultured by two different methods, directly on the agar medium and indirectly through enrichment selective medium previously. The result showed that the directly inoculation could isolate C. diphtheriae as many as 3 out of 18 samples, whereas indirectly method by using enrichment selective medium could isolate and identify 9 out of 18 samples. In conclusion, enrichment selective medium (sheep blood + tellurite) may improve the examination sensitivity of bacteria causing diphtheria identification in the laboratory.

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DE SMEDT, J. M., and R. BOLDERDIJK. "Collaborative Study of the International Office of Cocoa, Chocolate, and Sugar Confectionery on the Use of Motility Enrichment for Salmonella Detection in Cocoa and Chocolate." Journal of Food Protection 53, no. 8 (August 1, 1990): 659–64. http://dx.doi.org/10.4315/0362-028x-53.8.659.

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A comparative collaborative study was performed in 15 laboratories to validate the use of motility enrichment on Modified Semisolid Rappaport-Vassiliadis (MSRV) medium for Salmonella detection in cocoa and chocolate products. The use of MSRV was compared with a cultural procedure using Rappaport-Vassiliadis broth and selenite cystine broth as selective enrichments. Artificially contaminated milk chocolate samples as well as Salmonella reference capsules added to Salmonella-free cocoa and milk chocolate were used as test samples. Motility enrichment produced 347 positive test results compared to 320 for the cultural procedure. For samples containing a lactose positive Salmonella strain, motility enrichment was far more productive than the cultural procedure, while for the other samples no significant statistical difference in the productivity of both procedures was observed at the 5% level.

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Pauly, Natalie, Yvonne Klaar, Tanja Skladnikiewicz-Ziemer, Katharina Juraschek, Mirjam Grobbel, Jens André Hammerl, Lukas Hemmers, et al. "Isolation Procedure for CP E. coli from Caeca Samples under Review towards an Increased Sensitivity." Microorganisms 9, no. 5 (May 20, 2021): 1105. http://dx.doi.org/10.3390/microorganisms9051105.

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Due to the increasing reports of carbapenemase-producing Enterobacteriaceae (CPE) from livestock in recent years, the European Reference Laboratory for Antimicrobial Resistances (EURL-AR) provided a protocol for their recovery from caecum and meat samples. This procedure exhibited limitations for the detection of CPE with low carbapenem MIC values. Therefore, it was modified by a second, selective enrichment in lysogeny broth with cefotaxime (CTX 1 mg/L) and with meropenem (MEM 0.125 mg/L) at 37 °C under microaerophilic conditions. By Real-time PCR, these enrichments are pre-screened for the most common carbapenemase genes. Another adaptation was the use of in-house prepared MacConkey agar with MEM and MEM+CTX instead of commercial selective agar. According to the EURL-method, we achieved 100% sensitivity and specificity using the in-house media instead of commercial agar, which decreased the sensitivity to ~75%. Comparing the method with and without the second enrichment, no substantial influence on sensitivity and specificity was detected. Nevertheless, this enrichment has simplified the CPE-isolation regarding the accompanying microbiota and the separation of putative colonies. In conclusion, the sensitivity of the method can be increased with slight modifications.

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Easter, M. C., and D. M. Gibson. "Rapid and automated detection of salmonella by electrical measurements." Journal of Hygiene 94, no. 3 (June 1985): 245–62. http://dx.doi.org/10.1017/s0022172400061477.

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SUMMARYA rapid method for determining the presence of salmonella in food is described. It consists of pre-enrichment in buffered peptone water modified by the addition of dulcitol. and trimethylamine oxide, followed by selective enrichment in a selenite—cystine broth with similar modifications. Changes in the conductance of the selective enrichment broth are monitored continuously using a suitable impediometric instrument. Most of theSalmonellaspp. tested gave a fast (˜100 μS/h) and large (> 600 μS) change in conductance, other enteric bacteria much less or no change. The assay is usually complete within 24 h. Samples of foodstuffs, naturally and artificially contaminated withSalmonellaspp., were all correctly classified. Some strains ofCitrobacter freundiiproduced a false positive conductance response, and they could not be selectively eliminated using antibiotics or cyanide. The conductance method is simple and easy to use, gives rapid results and involves less media and subculturing than is required for traditional methods.

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Wang, Yulin, Renxin Zhao, Lei Liu, Bing Li, and Tong Zhang. "Selective enrichment of comammox from activated sludge using antibiotics." Water Research 197 (June 2021): 117087. http://dx.doi.org/10.1016/j.watres.2021.117087.

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Nessen, Merel A., Gertjan Kramer, JaapWillem Back, Jeremy M. Baskin, Linde E. J. Smeenk, Leo J. de Koning, Jan H. van Maarseveen, et al. "Selective Enrichment of Azide-Containing Peptides from Complex Mixtures." Journal of Proteome Research 8, no. 7 (July 6, 2009): 3702–11. http://dx.doi.org/10.1021/pr900257z.

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Tan, S., JS Chen, LJ Sun, and HR Yao. "Selective Enrichment of Hepatocellular Cancer Stem Cells by Chemotherapy." Journal of International Medical Research 37, no. 4 (August 2009): 1046–56. http://dx.doi.org/10.1177/147323000903700409.

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This study investigated the enrichment of cancer stem cells (CSCs) in hepatocellular carcinoma (HCC) by chemotherapy. SMMC-7721 cells were inoculated into mice treated with 0, 2, 5 or 10 mg/kg cyclophosphamide (CTX). Tissue from the resulting tumours was re-inoculated into CTX-treated mice two more times, thus producing three generations of tumour cells for each dose of CTX. Chromosome and fluorescence-activated cell sorting analyses were performed to determine the purity of the enriched cells. Sphere culture, colony formation and proliferation assays demonstrated that the self-renewal potential, proliferative activity and clonogenicity of the enriched cells in vitro increased with increasing chemotherapy dose and generation. The ability of the enriched cells to produce xenograft tumours in mice was also dependent on chemotherapy dose and generation. In conclusion, subjecting HCC cells to chemotherapy in vivo enriched the samples for HCC CSCs in a dose-and generation-dependent manner.

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THOMAS, R. L., C. T. CORDLE, L. G. CRISWELL, P. H. WESTFALL, and S. F. BAREFOOT. "Selective Enrichment of Proteins Using Formed-In-Place Membranes." Journal of Food Science 57, no. 4 (July 1992): 1002–5. http://dx.doi.org/10.1111/j.1365-2621.1992.tb14342.x.

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Ogunro, Olayinka O., and Xiao-Qian Wang. "Quantum Electronic Stability in Selective Enrichment of Carbon Nanotubes." Nano Letters 9, no. 3 (March 11, 2009): 1034–38. http://dx.doi.org/10.1021/nl803379d.

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Dong, Mingming, Yangyang Bian, Jing Dong, Keyun Wang, Zheyi Liu, Hongqiang Qin, Mingliang Ye, and Hanfa Zou. "Selective Enrichment of Cysteine-Containing Phosphopeptides for Subphosphoproteome Analysis." Journal of Proteome Research 14, no. 12 (November 20, 2015): 5341–47. http://dx.doi.org/10.1021/acs.jproteome.5b00830.

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Takakura, Daisuke, Akira Harazono, Noritaka Hashii, and Nana Kawasaki. "Selective glycopeptide profiling by acetone enrichment and LC/MS." Journal of Proteomics 101 (April 2014): 17–30. http://dx.doi.org/10.1016/j.jprot.2014.02.005.

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Janssen, Peter H. "Selective enrichment and purification of cultures of Methanosaeta spp." Journal of Microbiological Methods 52, no. 2 (February 2003): 239–44. http://dx.doi.org/10.1016/s0167-7012(02)00181-1.

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Zingsem, Jürgen, Thomas Zeiler, Robert Zimmermann, Nimrod Schwella, Volker Weisbach, Wolfgang Siegert, and Reinhold Eckstein. "Selective enrichment of hematopoietic progenitor cells from peripheral blood." Transfusion Science 14, no. 1 (January 1993): 75–77. http://dx.doi.org/10.1016/0955-3886(93)90059-4.

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Ralovich, B. "Data on the enrichment and selective cultivation of listeriae." International Journal of Food Microbiology 8, no. 3 (June 1989): 205–17. http://dx.doi.org/10.1016/0168-1605(89)90015-9.

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Columé, A., S. Cárdenas, M. Gallego, and M. Valcárcel. "Selective enrichment of 17 pyrethroids from lyophilised agricultural samples." Journal of Chromatography A 912, no. 1 (March 2001): 83–90. http://dx.doi.org/10.1016/s0021-9673(01)00546-5.

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Knutsson, Rickard, Ylva Blixt, Halfdan Grage, Elisabeth Borch, and Peter Rådström. "Evaluation of selective enrichment PCR procedures for Yersinia enterocolitica." International Journal of Food Microbiology 73, no. 1 (February 2002): 35–46. http://dx.doi.org/10.1016/s0168-1605(01)00690-0.

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Yan, Jingyu, Xiuling Li, Long Yu, Yu Jin, Xiuli Zhang, Xingya Xue, Yanxiong Ke, and Xinmiao Liang. "Selective enrichment of glycopeptides/phosphopeptides using porous titania microspheres." Chemical Communications 46, no. 30 (2010): 5488. http://dx.doi.org/10.1039/c000094a.

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Thingholm, Tine E., Thomas J. D. Jørgensen, Ole N. Jensen, and Martin R. Larsen. "Highly selective enrichment of phosphorylated peptides using titanium dioxide." Nature Protocols 1, no. 4 (November 2006): 1929–35. http://dx.doi.org/10.1038/nprot.2006.185.

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Messner, Christoph B., Munazza R. Mirza, Matthias Rainer, Oliver M. D. Lutz, Yüksel Güzel, Thomas S. Hofer, Christian W. Huck, Bernd M. Rode, and Günther K. Bonn. "Selective enrichment of phosphopeptides by a metal–organic framework." Analytical Methods 5, no. 9 (2013): 2379. http://dx.doi.org/10.1039/c3ay40308d.

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