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- Olsson, Crister, et al.
(författare)
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DNA based classification of food associated Enterobacteriaceae previously identified by biolog GN microplates
- 2004
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Ingår i: Systematic and Applied Microbiology. - : Elsevier BV. - 0723-2020 .- 1618-0984. ; 27:2, s. 219-228
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Tidskriftsartikel (refereegranskat)abstract
- Enterobacteriaceae are frequently isolated from food products and it is essential to have methods for correct identification for both food hygiene and epidemiology reasons. Phenotypic methods are not always sufficient and have to be supplemented by DNA based methods. In the present study, 70 strains of Enterobacteriaceae derived from milk, fish and meat that had previously been identified by Biolog GN Microplates were genomically classified together with 15 representative type strains of species of Enterobacteriaceae. The field strains were dominated by Hafnia alvei, Serratia liquefaciens and Rahnella aquatilis. All strains were subjected to temporal temperature gel electrophoresis (TTGE) analysis using amplicons encompassing the V3, V4 and V9 variable regions of the 16S rRNA gene. Selected strains were analysed by ribotyping and partial 16S rDNA sequencing. The type strains were differentiated into 10 different TTGE groups. Two of the groups contained two type strains. Enterobacter aerogenes and Klebsiella planticola were not distinguished due to their identical sequences and Yersinia ruckeri and Citrobacter freundii showed the same migration pattern. The 70 food strains could be differentiated into 14 TTGE groups where 33 strains (47.1%) could be assigned to TTGE groups including type or reference strains. Rabnella strains were dispersed into three TTGE groups of which one group corresponded to Rahnella genomospecies 1 and one to genomospecies 3. The grouping of Rabnella strains was supported by ribotyping and phylogenetic analysis. TTGE can be a useful additional tool for identification on the species level of food related Enterobacteriaceae.
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| 2. |
- Olsson, Crister, et al.
(författare)
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The bacterial flora of fresh and chill-stored pork: analysis by cloning and sequencing of 16S rRNA genes.
- 2003
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Ingår i: International Journal of Food Microbiology. - 0168-1605. ; 83:3, s. 245-252
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Tidskriftsartikel (refereegranskat)abstract
- The composition of the initial bacterial flora of pork and the development of the flora after storage at +4 °C for 4 days were analysed by amplification, cloning and sequencing of 16S rDNA. A total of 122 clones were obtained, with lengths of ≥400 nucleotides and ≥95% similarity to database sequences. Nineteen clones were similar to sequences in database not assigned to any genera. Fourteen different genera were represented in clones from fresh meat, with 36.5% of the clones most resembling Acinetobacter and 17.3% resembling Staphylococcus and Macrococcus. After storage, the clones were composed of six different genera, with 44.3% resembling Pseudomonas, 17.1% resembling Aeromonas and only 14.3% resembling Acinetobacter. This study shows that the overall pattern of the initial and chill-stored pork flora, as shown by a molecular approach, was in agreement with results obtained in previous studies using traditional cultivation methods.
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| 3. |
- Olsson, Crister, et al.
(författare)
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The Yersinia HPI is present in Serratia liquefaciens isolated from meat.
- 2003
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Ingår i: Letters in Applied Microbiology. - 0266-8254. ; 37:4, s. 275-280
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Tidskriftsartikel (refereegranskat)abstract
- Aims: The aim of the study was to screen the Enterobacteriaceae flora of meat for the presence of bacteria harbouring the Yersinia high-pathogenicity island (HPI). Methods and Results: Bacteria from 29 meat and 29 liver samples were isolated on violetred bile glucose agar. A total of 197 isolates were screened for the presence of the irp2 gene, encoded within the HPI, by PCR. One isolate that was positive for irp2 gene was also positive for the fyuA, irp1, ybtP/ybtQ, ybtX/ybtS and int/asn tRNA genes by PCR. The presence of fyuA, irp1 and irp2 genes was confirmed by Southern hybridization. Conclusions: The isolate was identified as Serratia liquefaciens by sequencing of the 16S rRNA gene and by ribotyping. Significance and Impact of the Study: This is the first report of a Serratia harbouring the Yersinia HPI. Serratia is a frequently occurring Enterobacteriaceae genus in chill-stored meat.
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