Premium
The development of a conductimetric assay for automated detection of metabolically active soft rot Erwinia spp. in potato tuber peel extracts
Author(s) -
Fraaije B. A.,
Birnbaum Y.,
Franken A. A. J. M.,
Van den Bulk R.W.
Publication year - 1996
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1996.tb03522.x
Subject(s) - erwinia , pectate lyase , bacteria , enterobacteriaceae , food science , microbiology and biotechnology , chemistry , pseudomonas , blackleg , retting , enterobacter , biology , biochemistry , botany , escherichia coli , pectinase , gene , genetics , brassica , enzyme
Four media were tested for their ability to detect the soft rot potato pathogens Erwinia chrysanthemi (Ech) and Erwinia carotovora ssp. atroseptica (Eca) in potato tubers by means of automated conductance measurements. The specificity of the conductimetric assays was determined by testing a set of different Erwinia spp. and potato‐associated saprophytes, including the genera Pseudomonas, Bacillus, Enterobacter and Flavobacterium. All bacteria tested produced conductance responses in Special Peptone Yeast Extract, whereas in minimal medium with L‐asparagine only Erwinia spp. and Pseudomonas spp. were able to generate large conductance responses. In minimal medium supplemented with glucose and trimethylamine‐ N ‐oxide only Enterobacteriaceae, Erwinia spp. included, generated conductance responses, while with pectate as sole carbon source only Erwinia spp. produced distinct conductance responses. The pectate medium proved to be particularly useful for specific automated conductimetric detection of Erwinia spp. in potato peel extracts. Within 48 h, the detection threshold of the conductimetric assay for Eca varied between 10 2 and 10 3 cfu per ml peel extract at both incubation temperatures of 20° and 26°C. Ech was detected at concentrations of 10 4 –10 5 or 10 3 –10 4 cfu ml ‐1 at 20° and 26°C, respectively. To eliminate ‘false’‐positive reactions in conductimetry caused by Erwinia carotovora ssp. carotovora , results of the conductance measurements have to be confirmed by other techniques, like serology or DNA assays.