Vacuolar localisation of anthocyanin pigmentation in microgreen cotyledons of basil, cabbage and mustard greens does not impact on colonisation by Shiga-toxigenic Escherichia coli O157:H7

Kathryn M. Wright, Jacqueline Marshall, Peter J. Wright, Nicola J. Holden (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
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Abstract

Microgreens, the immature plants harvested after a few weeks of growth, are perceived as a heathy, nutritious food ingredient but may be susceptible to colonisation by human pathogens including Shiga-toxigenic Escherichia coli (STEC). Some microgreen cultivars accumulate anthocyanins or secrete essential oils which, when extracted or purified, have been reported to inhibit bacterial growth. Therefore, the impact of anthocyanins on bacterial colonisation by STEC (Sakai) was compared for three species that have pigmented cultivars: basil (Ocimum basilicum L.), cabbage (Brassica oleracea L.) and mustard greens (Brassica juncea L.). Inoculation with low concentrations of STEC (Sakai) (3 log10 colony forming units/ml (CFU/ml)) during seed germination resulted in extensive colonisation at the point of harvest, accumulating to ∼ 8 log10 CFU/g FW in all cultivars. Bacterial colonies frequently aligned with anticlinal walls on the surface of epidermal cells of the cotyledons and, in basil, associated with peltate and capitate gland cells. Crude lysates of pigmented and non-pigmented basil cultivars had no impact on STEC (Sakai) growth rates, viability status or biofilm formation. Anthocyanins are located within plant vacuoles of these microgreen cultivars and did not affect colonisation by STEC (Sakai) and pigmentation therefore cannot be considered as a controlling factor in bacterial interactions.

Original languageEnglish
Article number104367
Number of pages6
JournalFood Microbiology
Volume116
Early online date21 Aug 2023
DOIs
Publication statusPublished - Dec 2023

Keywords

  • Foodborne pathogen
  • Fresh produce
  • Microherb
  • Vegetable

ASJC Scopus subject areas

  • Food Science
  • Microbiology

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