Open AccessThe role of l-arabinose metabolism for Escherichia coli O157:H7 in edible plants
Author(s) -
Louise Crozier,
J. Marshall,
Ashleigh Holmes,
Kathryn M. Wright,
Yannick Rossez,
Bernhard Merget,
Sonia Humphris,
Ian K. Toth,
Robert W. Jackson,
Nicola Holden
Publication year - 2021
Publication title -
microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 179
eISSN - 1465-2080
pISSN - 1350-0872
DOI - 10.1099/mic.0.001070
Subject(s) - escherichia coli , metabolism , arabinose , chemistry , microbiology and biotechnology , biology , biochemistry , food science , fermentation , xylose , gene
Arabinose is a major plant aldopentose in the form of arabinans complexed in cell wall polysaccharides or glycoproteins (AGP), but comparatively rare as a monosaccharide. l-arabinose is an important bacterial metabolite, accessed by pectolytic micro-organisms such as Pectobacterium atrosepticum via pectin and hemicellulose degrading enzymes. However, not all plant-associated microbes encode cell-wall-degrading enzymes, yet can metabolize l-arabinose, raising questions about their use of and access to the glycan in plants. Therefore, we examined l-arabinose metabolism in the food-borne pathogen Escherichia coli O157:H7 (isolate Sakai) during its colonization of plants. l-arabinose metabolism ( araBA ) and transport ( araF ) genes were activated at 18 °C in vitro by l-arabinose and expressed over prolonged periods in planta . Although deletion of araBAD did not impact the colonization ability of E. coli O157:H7 (Sakai) on spinach and lettuce plants (both associated with STEC outbreaks), araA was induced on exposure to spinach cell-wall polysaccharides. Furthermore, debranched and arabinan oligosaccharides induced ara metabolism gene expression in vitro , and stimulated modest proliferation, while immobilized pectin did not. Thus, E. coli O157:H7 (Sakai) can utilize pectin/AGP-derived l-arabinose as a metabolite. Furthermore, it differs fundamentally in ara gene organization, transport and regulation from the related pectinolytic species P. atrosepticum , reflective of distinct plant-associated lifestyles.