Seed inoculation with antagonistic bacteria limits occurrence of E. coli O157:H7gfp+ on baby spinach leaves

Abstract

Backround During the last decades, outbreaks of foodborne illnesses have increasingly been linked to fresh and/or minimally processed fruit and vegetables. Enterohemorrhagic Escherichia coli was the causal agent for major outbreaks in Europe with leafy green vegetables and sprouts. To improve food safety, microbial antagonism has received attention during recent years and could be one of the solution to prevent contamination of food borne pathogens on fresh produce. Here we investigate the antagonistic effect of three bacterial strains (Pseudomonas orientalis, P. flavescens and Rhodococcus sp.) isolated from spinach leaves against E. coli O157:H7gfp + under laboratory and greenhouse conditions. Results Our results shows that significantly less culturable E.coli O157:H7gfp + were retrieved from the spinach canopy subjected to antagonist seed treatment than canopy inoculation. Seeds inoculated with Rhodococcus sp. significantly reduced growth of E. coli O157:H7gfp + compared with the other antagonists. The result from the in vitro study shows a significant reduction of growth of E. coli O157:H7gfp+, but only after 44 h when E. coli O157:H7gfp + was propagated in a mixture of spent media from all three antagonists. Conclusions The antagonistic effect on phyllospheric E.coli O157:H7gfp + observed after seed inoculation with Rhodococcus sp. might be an indication of induced resistance mechanism in the crop. In addition, there was a small reduction of culturable E.coli O157:H7gfp + when propagated in spent media from all three antagonists. Nutritional conditions rather than metabolites formed by the three chosen organisms appear to be critical for controlling E. coli O157:H7gfp+.

Keywords

Bacterial antagonist; E. coli O157: H7; Pseudomonas flavescens; Pseudomonas orientalis; Rhodococcus sp.; Spinach

Published in

BMC Microbiology
2022, volume: 22, number: 1, article number: 131

SLU Authors

• Karlsson, Maria

  • Department of Biosystems and Technology, Swedish University of Agricultural Sciences
    

• Uhlig, Elisabeth

  • Lund University

• Alsanius, Beatrix

  • Department of Biosystems and Technology, Swedish University of Agricultural Sciences
    

Associated SLU-program

SLU Plant Protection Network

Global goals (SDG)

SDG2 Zero hunger
SDG3 Good health and well-being
SDG12 Responsible consumption and production

UKÄ Subject classification

Food Science

Publication identifier

• DOI: https://doi.org/10.1186/s12866-022-02550-w

Permanent link to this page (URI)

https://res.slu.se/id/publ/117159