摘要:

A technique based on the addition of a red cells top layer to a selective plating medium after listeria growth is proposed in order to detect directly the haemolytic activity of pathogenic listeria colonies. It was applied to different selective plating media (modified McBride agar, lithium chloride‐phenylethanol‐moxalactam, listeria selective medium–Oxford formulation, polymyxin‐acriflavine‐lithium chloride‐ceftazidime‐aesculin‐mannitol and LSAMM). The haemolytic activity of listeria colonies was more easily detected with the top layer than when red cells were incorporated in the selective plating medium. The LSAMM was the best medium for the recovery and identification ofListeria monocytogenescolonies by this technique (threeListeria monocytogenescolonies were distinguished among 2520Listeria innocuacoloni

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1989.tb00305.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A number of selective media forListeriahave been tested for use with electrical methods for growth detection. A modification of an existing medium containing acriflavine, ceftazidime, nalidixic acid and aesculin gave good selectivity and signal response. The capacitance signal was more reliable than conductance and was characteristic ofListeriaspp.

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1989.tb00306.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Thirteen monoclonal antibodies reactive with HT‐2 were prepared by using a HT‐2 hemisuccinate coupled to human serum albumin as antigen for the immunization of BALB/c mice. In a competitive enzyme immunoassay on a double antibody solid phase using HT‐2 hemisuccinate coupled to horseradish peroxidase as enzyme linked toxin all antibodies reacted much better with T‐2 toxin and acetyl T‐2 than with HT‐2. Eleven antibodies showed almost the same sensitivity and specificity, and one of these, designated 3E2, is extensively described. Its cross‐reactivities with HT‐2, T‐2 toxin, acetyl T‐2, iso T‐2, T‐2 tetraol tetraacetate and T‐2 triol were 1·0, 140·2, 161·2, 0·32, 0·14 and 0·016, respectively. Two other antibodies, designated 2A4 and 2A5, behaved quite differently. The cross‐reactivities of antibody 2A4 with these toxins were: 1·0, 113·9, 374·4, 1·35, 0·34 and 0·023, respectively; for antibody 2A5 they were 1·0, 46·1, 155·4, 8·31, 0·9 and 0·08, respectively. All antibodies proved to be IgGl. By using the antibody 3E2 a highly sensitive and very specific enzymc immunoassay for the detection of T‐2 toxin was developed. The detection

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1989.tb00307.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Incubation of campylobacter selective broth at 37°C for 48 h followed by selective plating and incubation at 43°C improved significantly the isolation rate ofCampylobacter jejunifrom naturally contaminated samples of river water and artificially contaminated samples of raw milk. The use of such a technique had no effect, however, on the isolation ofC. jejunifrom chicken ski

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1989.tb00308.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Regeneration of protoplasts ofBacillus coagulanswas optimized by using low lysozyme concentrations and glycerol as the osmotic support. Protoplasts formed from cells grown at higher temperatures were thermostable and capable of regeneration at 55°C. Transfer of plasmids pAB224 and pUB110, using either whole cells or protoplast transformation was not achieved, despite using a variety of conditions. However, plasmid transfer was achieved by fusion withB. subtilisprotoplasts containing plasmid pAB224

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1989.tb00309.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Growth ofStaphylococcus aureusat 15°C, with and without addition of representative spoilage bacteria, was studied in cooked, whole chicken meat and chicken broth. In the absence of competitors, the organism grew better in broth culture than on whole meat, but multiplied more slowly in broth when other organisms were present, even from twice the previous level of inoculum. The presence of competitors had no marked effect on the growth ofStaph. aureuson whole meat. Enterotoxin A was not produced at 15°C on either whole meat or in broth, and occurred at 20°C only in pure culture. At 30° and 37°C, toxin was produced whether or not competitors were present. Toxin production byStaph. aureusappeared to be influenced more by growth temperature than by bacterial competi

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1989.tb00310.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Recombinant bacteria which express only theluxA andluxB genes have a bioluminescent phenotype providing exogenous long chain aldehyde is supplied in the medium or as a vapour. As an integral part of the biochemistry of photon emission, sub‐saturating concentrations of aldehyde are reflected as sub‐maximal cellular bio‐luminescence. This may be correlated in a kinetic analysis to provide apparentKmvalues. An analysis of such data across a spectrum of Gram‐positive and Gramnegative bacteria was used to provide a limit for the sensitivity of aldehyde detection. The future development of a rapid bioluminescence‐based rancidity test in foods and oils is

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1989.tb00311.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A rapid iodine reduction method was developed for predicting the quality of gari. Good quality samples took longer (21·0 ± 4·5s) to reduce iodine than poor quality samples (2·2 ± 0·42 s). There was a strong association between quality and reduction time (r= 0·97, df = 12) and storage period (r= 0·99, df = 12) and the reduction time was also dependent on bacterial numbers. Gari stored at low temperatures contained fewer micro‐organisms and retained its quality longer than that kept at higher temperatures. The quality of gari can be predicted from iodine reduct

ISSN:0266-8254    

DOI:10.1111/j.1472-765X.1989.tb00312.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY