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Research article2021Peer reviewedOpen access

Use of bacterial strains antagonistic to Escherichia coli for biocontrol of spinach: A field trial

Uhlig, E.; Kjellstrom, A.; Nurminen, N.; Olsson, C.; Oscarsson, E.; Canaviri-Paz, P.; Mogren, L.; Alsanius, B.; Molin, G.; Hakansson, A.


To counteract global food safety hazards related to raw consumption of ready-to-eat leafy vegetables, a method to improve bacterial status using antagonistic bacteria was studied under field conditions. This is the first study to identify potential Escherichia coli antagonists from the native microbiota on leafy green vegetables and evaluate their effect in an industrial field production setting. Bacterial strains were isolated from different types of leafy green vegetables and selected upon their effect against E. coli in vitro, and out of 295 tested bacterial strains, 37 showed an antagonistic effect. Four of those antagonistic strains were coated in separate treatments onto spinach seeds and planted in the field. Both seeds and plants were analyzed by Illumina MiSeq next generation sequencing (NGS), and it was seen that the microbiota of the plants contained lower relative abundance of plant and human pathogenic genera. Higher beta-diversity was observed for the samples treated with Bacillus coagulans LMG P-32205 and B. coagulans LMG P-32206 compared to control, indicating that those strains have induced substantial changes in the native microbiota of the leaves. A reduction of Escherichia-Shigella was seen for two of the isolates (Pseudomonas cedrina LMG P-32207 and Pseudomonas punonenis LMG P-32204) as the seeds developed into plants. Seeds inoculated with two of the strains (B. coagulans LMG P-32205 and B. coagulans LMG P-32206) had increased levels of Lactobacillaceae, and treatment with B. coagulans LMG P-32206 resulted in lower levels of Pantoea (from 31.4 to 12.2%). These results encourage the usage of bacterial antagonists as part of a global solution to reduce the risk of human pathogens on leafy green vegetables.


Leafy-green vegetables; Escherichia coli; Native microbiota; Biological control

Published in

Innovative Food Science and Emerging Technologies
2021, Volume: 74, article number: 102862

      SLU Authors

    • Associated SLU-program

      SLU Plant Protection Network

      Sustainable Development Goals

      End hunger, achieve food security and improved nutrition and promote sustainable agriculture

      UKÄ Subject classification

      Food Science

      Publication identifier


      Permanent link to this page (URI)