ISHS Acta Horticulturae 530: International Symposium on Methods and Markers for Quality Assurance in Micropropagation
PERSISTENCE IN IN VITRO CULTURES OF CABBAGE (BRASSICA OLERACEA VAR CAPITATA L.) OF HUMAN FOOD POISONING PATHOGENS: ESCHERICHIA COLI AND SERRATIA MARCESCENS |
| Authors: | S.M. Rafferty, S. Williams, F.R. Falkiner, A.C. Cassells |
| Keywords: | bacterial contamination, clinical isolates, hydroponic culture, plant tissue culture, photoautrotrophic culture, pulsed field gel electrophoresis |
| Abstract:
An increase in reports of disease outbreaks associated with fresh and ready-to-eat vegetables prompted this study to evaluate the risk of transmission of human food poisoning organisms in micropropagated vegetables. Here, cabbage is used as a model plant and Escherichia coli and Serratia marcescens as model human pathogens. Surface sterilised cabbage seeds were germinated on water agar and co- inoculated with E. coli or S. marcescens. Nodal explants were then used to establish autotrophic tissue cultures. The culture medium and micropropagated plants were examined microbiologically at each subculture. The latter were surface sterilised and the tissues homogenised prior to bacterial screening. Both model strains were recovered from the culture medium and tissue homogenate. Biochemical identification was carried out using the API system, and epidemiological typing was performed using pulsed field gel electrophoresis (PFGE). E. coli and S. marcescens were found to persist in autotrophic (aseptic microhydroponic) culture, indicating that the carbon sources required for growth were acquired from microplant exudates. E. coli and S. marcescens were repeatedly re-isolated from the progeny microplants after serial subcultures. Some microplants were asymptomatic in the first subculture; both isolates became pathogenic in vitro in the third subcultures. | |
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