Agnes Weiss


Last Name

Weiss

First Name

Agnes

ORCID

0000-0002-4462-5278

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2011 - 20193
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Publications1 - 3 of 3
  • Application of MALDI-TOF mass spectrometry and specific PCR for tracking of E. coli O157:Hˉ strain 431/97 in Batavia lettuce
    Item type: Journal Article
    Weiss, Agnes; Heinold, Susanne; Brunisholz, René; et al. (2019)
    Chemical and Biological Technologies in Agriculture
    Background In this study, lettuce roots and leaves were contaminated with enterohemorrhagic Escherichia coli O157:H− strain 431/97 under greenhouse conditions. Furthermore, the internalization of strain 431/97 in lettuce roots and leaves was examined. To track the inoculated bacteria during the experiments and to differentiate them from the autochthonous microbiota, a combined protocol including matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and PCR was established. Results At different time points after inoculation of Batavia lettuce with 5.5 × 106 cfu/mL (high inoculation level) or 3.0 × 101 cfu/mL (low inoculation level) E. coli O157:H− strain 431/97 as well as sterile 0.9% (w/v) sodium chloride solution (negative control), samples from the root and the leaf were taken and surface disinfected with gentamicin. After homogenization, microorganisms were isolated from the samples and analyzed by MALDI-TOF MS. Analysis of the root samples resulted in bacterial counts of 1.0 × 102–1.0 × 106 cfu/0.25 g depending on the inoculated viable counts and the incubation period. In the leaf samples, strain 431/97 was not detected. The investigation of the viable cell counts of E. coli O157:H− 431/97 following irrigation of the leaves resulted in bacterial counts of 102 cfu/0.25 g for the disinfected leaf samples. Conclusions Thus, the established protocol is suitable for detecting the investigated strain under greenhouse conditions in plant infection experiments. This strain may indeed survive in the soil, but did not enter the plant via the root in detectable numbers. Contrarily, viable counts exceeding the generally accepted infective dose of less than 100 cells for enterohemorrhagic E. coli were determined internalized after irrigation of the leaves. As this may pose a risk for the consumer, the present study provides a valuable set of tools for further research.
  • Development of a real-time PCR based system for the detection of Cronobacter sakazakii in powdered milk products
    Item type: Other Conference Item
    Rall, J.; Weiss, Agnes; Loessner, Martin; et al. (2011)
    International Journal of Medical Microbiology
  • Differential transcriptome analysis of enterohemorrhagic Escherichia coli strains reveals differences in response to plant-derived compounds
    Item type: Journal Article
    Bufe, Thorsten; Hennig, André; Klumpp, Jochen; et al. (2019)
    BMC Microbiology
    Background Several serious vegetable-associated outbreaks of enterohemorrhagic Escherichia coli (EHEC) infections have occurred during the last decades. In this context, vegetables have been suggested to function as secondary reservoirs for EHEC strains. Increased knowledge about the interaction of EHEC with plants including gene expression patterns in response to plant-derived compounds is required. In the current study, EHEC O157:H7 strain Sakai, EHEC O157:H− strain 3072/96, and the EHEC/enteroaggregative E. coli (EAEC) hybrid O104:H4 strain C227–11φcu were grown in lamb’s lettuce medium and in M9 minimal medium to study the differential transcriptional response of these strains to plant-derived compounds with RNA-Seq technology. Results Many genes involved in carbohydrate degradation and peptide utilization were similarly upregulated in all three strains, suggesting that the lamb’s lettuce medium provides sufficient nutrients for proliferation. In particular, the genes galET and rbsAC involved in galactose metabolism and D-ribose catabolism, respectively, were uniformly upregulated in the investigated strains. The most prominent differences in shared genome transcript levels were observed for genes involved in the expression of flagella. Transcripts of all three classes of the flagellar hierarchy were highly abundant in strain C227–11φcu. Strain Sakai expressed only genes encoding the basal flagellar structure. In addition, both strains showed increased motility in presence of lamb’s lettuce extract. Moreover, strain 3072/96 showed increased transcription activity for genes encoding the type III secretion system (T3SS) including effectors, and was identified as a powerful biofilm-producer in M9 minimal medium. Conclusion The current study provides clear evidence that EHEC and EHEC/EAEC strains are able to adjust their gene expression patterns towards metabolization of plant-derived compounds, demonstrating that they may proliferate well in a plant-associated environment. Moreover, we propose that flagella and other surface structures play a fundamental role in the interaction of EHEC and EHEC/EAEC with plants.
Publications1 - 3 of 3