摘要:

A membrane lifting technique was developed for direct rapid detection of Escherichia coli 0157:H7 in inoculated ground meats. Duplicate groups of 2 meatballs were inoculated with volumes of 0.1‐ml of a serial dilution (1:10) of E. coli 0157:H7 or a mixed culture containing one strain of E. coli 0157:H7 and a non‐0157:H7E. coli serotype (E. coli ATCC 25922). Each meatball was sampled by sandwiching with 2 pieces of nitrocellulose membranes and pressing against each other to the center of the meatball. The membranes were in contact with the meats for 10 min to lift the bacteria. The membranes were removed and incubated on MacConkey‐sorbitol agar plates with the meat contact side up. After 18 h incubation at 37C, an immunostain was performed directly on the membranes for detection of the presence or absence of E. coli 0157:H7. This method was found to be sensitive enough to detect as few as 1 to 2 cells of E. coli 0157:H7 inoculated on surfaces of 18‐g meatballs. This method might be used as a rapid presumptive test for E. coli

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1996.tb00120.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Very little is known about the growth physiology and metabolic niche of the human oral isolate Selenomonas sputigena. The objective of this study was to devise a minimal medium for comparing growth rates and fermentation of rumen Selenomonas ruminantium strains with S. sputigena. When anaerobically grown on a minimal glucose medium containing yeast extract as the only chemically undefined component, S. sputigena produced acetate, propionate, and succinate while S. ruminantium strains produced primarily lactate. When strains were compared (P<0.05) for each carbon source that yielded growth, rumen strain HD4grew faster than all other strains on glucose, cellobiose and glycerol while strain GA192 grew faster on trehalose. Rumen strains GA192, PC18, and HD4grew faster on mannitol than rumen strains D and GA31. S. sputigena grew faster on lactate (0.38 ± 0.04) than any of the S. ruminantium strains. The minimal medium developed in this study should be useful for jurmer physiological studies on fermentation and metabolism in S. sputigena

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1996.tb00121.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Blue Lake, an insoluble dye, was evaluated as an indicator of potential bacterial penetration into eggs. Various groups of eggs (fresh‐laid; commercial; water‐washed) were dipped in 0.25% (w/v) Blue Lake in 0.1% Triton X‐100 solution for 2 min and incubated at room temperature up to 1 ± 24 h. Penetration was detected by counting the blue dots on shell membranes after breaking the eggs. Commercial eggs allowed the easiest penetration. All commercial eggs showed blue dots even at 2 min incubation and the average count reached 111/egg at 1 h. Water‐washed eggs allowed much less penetration than commercial eggs and the counts of blue dots on those eggs were 10/egg at 2 min and 22 at 1 h. Fresh‐laid eggs did not allow any penetration up to 24 h. Above results corresponded very well with the penetration study with Salmonella enteritidis and also with the morphological study of eggshell surfaces using electron microscopy where fresh‐laid eggs had intact cuticle layers, but commercial eggs did not. Thus, Blue Lake dye might be used as a rapid indicator of bacterial penetration throu

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1996.tb00122.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Botulinum type E toxin is a well recognized causative agent of seafood botulism poisoning. Underprocessing or postretort recontamination of preserved seafoods has resulted in sporadic cases of botulism. Currently, laboratory mice are being used to detect this toxin. However, it requires three to six days to obtain final results. A rapid method using monoclonal antibody (Mab) enzyme immunoassay was therefore developed. Hybridomas secreting specific Mab against the type E epitope were generated by fusion of SP/20‐Ag 14 myeloma cells with spleen cells from BALB/c mice immunized with botulinum type E neurotoxoid. Five potent, stable hybridomas were selected, cloned, propagated, and preserved in liquid nitrogen as cell lines. Immunoglobulin subisotyping showed these Mabs belonged to the IgG subclasses. No cross‐reaction was observed with culture supernatants of C. botulinum types A, B, and F or with crude toxins extracts of type C and D. Large quantities of Mabs were produced in ascites fluids, harvested, and affinity purified. A Mab‐based biotin‐avidin amplified double sandwich enzyme‐linked immunosorbent assay allowed detection of type E toxin in inoculated seafoods at levels equivalent to 1–10 MLDs/ml (

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1996.tb00123.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

A rapid chemiluminescent assay of total bacterial load that is based on the oxidation of luminol (5‐amino‐2,3‐dihydro‐1,4‐phthalazinedione) as catalyzed by bacterial iron protoporphyrins is described and compared to the ATP bioluminescent assay of microbial biomass. An assay format that elicits linear light output response to a range of analyte concentrations of model compounds such as hematin and various heme‐containing enzymes within the dynamic range of a BioOrbit 1251 luminometer is presented. When the assay was applied to eight pure bacterial cultures, the sensitivity was typically in the range of 104‐105cfu/ml, and was comparable to that obtained by the ATP assay. Similar levels of sensitivity can be derived from estimates of average values of 2.8 × 10‐18mole of heme/cfu and 1 × 10‐19mole of ATP/cfu. The potential of the luminal assay as an alternative rapid test for the estimation of total bacterial count in food and environmental s

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1996.tb00124.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Current methods that can be used for the identification of lactic acid bacteria (LAB) include: biochemical tests, pulsed field gel electrophoresis, and fatty acid analysis. These methods can be costly, time‐consuming, and technically difficult. We are investigating the microbial ecology of vegetable fermentations and are interested in the rapid identification of LAB isolates. We have adapted a PCR‐based ribotyping method for use with LAB. The PCR product (s) produced contains the sequences from the intergenie spacer regions between the rRNA genes. These products can be resolved by standard agarose or acrylamide gel electrophoresis. Using this method, we have identified PCR product electrophoresis banding patterns for the primary species of LAB found in vegetable fermentations, including those from the genera Lactobacillus, Leuconostoc, Lactococcus, and Pediococ

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1996.tb00125.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Variation in the fatty acid profile of Staphylococcus aureus WRRC B124 grown at varying temperatures was determined. The range of incubation temperatures tested induced both qualitative and quantitative differences in S. aureus fatty acid profile. While branched chained saturated fatty acids were the predominate species at 37C, C18:1 and C16:1 monounsaturated fatty acids were predominant at lower temperatures (12 and 19C). Iso‐branched C14:0, C16:0 and C18:0 saturated fatty acids were expressed exclusively at 37C and several C17:0 and C20:0 fatty acids were suppressed at 12C. Results demonstrated that S. aureus had altered fatty acid profile in response to changes in growth temperatur

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1996.tb00126.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1996.tb00127.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:1060-3999    

DOI:10.1111/j.1745-4581.1996.tb00119.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY