摘要:

OxyraseTMmembrane fraction was tested as an additive to nonselective BHI enrichment broth (0.1 unit/ml) to observe effects on growth of three strains of pathogenicEscherichia coli, including O157.H7 serotypes, and one nonpathogenic strain in culture broth and autoclaved ground beef systems. OxyraseTMenhanced the growth of all three pathogenic strains (inoculated at<1 cell/ml) in the broth system by shortening the lag phase period by 2–3 h. Growth of the nonpathogenicE. colistrain tested was suppressed by the presence of OxyraseTMduring the initial 4 h of incubation at 37C in both broth and autoclaved ground beef systems. Stimulatory effects of the enzyme added at 0.1 unit/ml were not observed in autoclaved meat systems whenE. colistrains were inoculated at 1–100 cells/g of meat during 24 h of incubation at 37C.BHI broth alone and used as a nonselective enrichment for autoclaved and fresh ground beef was evaluated to observe the effect of OxyraseTMon the oxidation‐reduction potential (Eh) of each system after 0, 4 and 18 h of incubation at 37C. OxyraseTMslightly lowered Eh after 4 and 18 h in BHI broth and fresh ground beef (in BHI). However, no Eh‐decreasing effects were seen at this time in systems containing autoclaved ground beef which may explain the lack of a stimulatory effect of OxyraseTMon growth ofE. coliin autoclaved grou

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00272.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Flow cell cytometry can be used in a sensitive fluorescent immunoassay to rapidly identify salmonellae of Groups D and E. Staphylococcal Protein A couples with the Fc region of many antibodies, especially immunoglobulin G. When a fluorescent marker, fluorescein isothiocyanate, is conjugated to Protein A, an antibody‐antigen reaction can be visualized in a flow cell cytometer with an appropriate optical sensor after excitation. Ten thousand cells were individually analyzed in each cytometer run within a minute. the resultant data, presented as histograms and tables, indicated the number of cells in the suspension reacting positively with the antiserum by fluorescence, cell size, distribution and light scatter. This provides an in‐depth analysis of the antibody‐antigen reaction not possible with other types of immunoa

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00273.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Flow cell cytometry is reported here as a rapid fluorescent immunoassay method to characterize monoclonal antibody production in hybridoma cultures.Actinomyces viscosuswas the bacterium chosen as a model to illustrate this procedure. Fluorescein isothiocyanate (FITC), coupled to staphylococcal Protein A (PA), was used as the fluorescent marker to detect and quantitate antigen‐antibody reactions. Flow cell cytometry was also used with rabbit polyclonal antibodies toA. viscosuscoupled with PAFITC for comparison and verification of the two procedures. Over 25,000 individual bacteria could be analyzed in a single cytometer injection within 2 min. the data, presented as histograms and figures, supported the feasibility of this method and also provided an in‐depth analysis of the degree of fluorescence, cell size, distribution and light scatter not available with most other immunoassay meth

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00274.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

An effective way for inoculation of bacteria into dry foods/ingredients that gives a uniform mixture was developed. In the first part of this experiment,Salmonella typhimuriumwas successfully inoculated into chalk. Chalk tubes were weighed then soaked in a broth withS. typhimuriumand allowed to dry back to their original weight. the dried chalk was made into a powder form. A viable cell count of this chalk, using a selective media forS. typhimurium, showed that the organism survived the drying while entrapped in the chalk. the “charged” chalk was used in an experiment as a dry inoculum where it was mixed with a low‐moisture poultry feed. In comparison to a liquid inoculum, the “charged” chalk was a superior way of inoculating into dry particles because it created a more homogenous mixture with the feed without altering any properties of the feed itself. the second part of this experiment entailed a shelf‐life study of the “charged” chalk. the same procedures for inoculating chalk were done using ten different cultures includingBacillus cereus, Clostridium perfringens, Escherichia coli, Enterobacter aerogenes, Lactobacillus plantarum, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus, andStreptococcus faecalis.Data showed that the cultures are stable in the chalk for at l

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00275.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Recombinant M13Hol phage containingEcoR1 restriction endonuclease fragments B, E, and F of adenovirus type 2 (Ad2) DNA were constructed by cloning into the uniqueEcoR1 site of the replicative form of the phage M13Hol176 DNA. Polarity of the adenovirus inserts in recombinant molecules was deduced by the following procedures: Viral DNA fragments obtained from Ad2 DNA molecules were purified, denatured, and subjected to electrophoresis. the separated DNA strands were transferred from agarose to nitrocellulose by the Southern procedure and hybridized with radioactive 3′‐end labeledHaeIII fragments of the recombinant phage DNAs. This procedure provided a rapid test for assaying strandedness of the cloned fragme

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00276.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Enterococci isolated from water (50 strains), clinical material (50 strains), pork products (25 strains), and other foods (25 strains) as well as 50 known strains were used to compare the abilities of four latex streptococcal grouping kits to correctly identify group D isolates. the Streptex kit (Wellcome Diagnostics) was 98.5% accurate and easiest to interpret. the Slidex Strepto kit (Vitek Systems) and Strepslide kit (NCS Diagnostics) also were acceptable; they were 96.5% and 96.0% accurate, respectively. When the Bacto Strep Grouping kit (Difco Laboratories) was used, 99% of the group D isolates were positive for both group D and group B, including enterococcal strains that are group D‐negativ

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00277.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

A competitive enzyme immunoassay for detection ofSalmonellasp. was developed in order to provide a sensitive assay for same‐day identification ofSalmonellasp. the assay could be performed in about 90 min and consisted of the following steps. Lipopolysaccharide derived fromSalmonella typhimuriumwas used to passively coat polystyrene 96‐well plates and tubes. A titrated amount of monoclonal antibody specific for an outer lipopolysaccharide core epitope commonly found inSalmoneilasp. was mixed with the prepared test sample prior to adding the mixture to the antigen coated matrix. Antibody bound to the immobilized antigen was detected with horseradish peroxidase labelled goat antimouse IgG (H&L chain).The analytical sensitivity of the assay was 3.1 ng and 5.6 ng of lipopolysac‐charide per ml for the plate and tube formats, respectively, if 25% inhibition or less was considered negative. This cutoff level was based on reactivity of unrelated monoclonal antibodies withS. typhimuriumlipopolysaccharide and lipopolysac‐charide fromE. coliwith theSalmonellaspecific monoclonal antibody in th

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00278.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Bactericidal properties of lysozyme alone and in combination with other antimicrobials were studiedin vitrousing the microtiter system and in hotdogs and hamburger with three pathogens:Salmonella enteriditisortyphimurium, Listeria monocytogenesATCC# 35152, andStaphylococcus aureusATCC# 69129. Lysozyme and nisin were found to be effective againstL. monocytogenesand were bactericidalin vitroat 9.27 mg/ml and 212.8 μg/ml, respectively. Twelve and one‐half μg/ml nisin and 5 mg/ml lysozyme were synergistic on hotdogs, where they reducedL. monocytogenescounts on MOX agar by 3 log10cycles on day 1, 3 log10cycles on day 2, and 2 log10cycles on day 3. No synergism was found in hamburger. the combinations of 5 mg/ml lysozyme and 12.5 μg/ml nisin and 5 mg/ml lysozyme, 12 μg/ml nisin, and. 02% EDTA acted synergistically on hotdogs to reduceS. aureuscounts by 2 and 3 log10cycles, respectively, over the 3‐day shelf‐l

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00279.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Book reviewed in this Article:Encyclopedia of Microbiology. Volumes 1,2,3, and 4. 1992. Edited by Joshua Lederberg.

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00280.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1992.tb00271.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY