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Physiological aspects of Listeria monocytogenes during inactivation accelerated by mild temperatures and otherwise non-growth permissive acidic and hyperosmotic conditions

journal contribution
posted on 2023-05-17, 00:46 authored by Zhang, D, Thomas RossThomas Ross, John BowmanJohn Bowman
Application of simultaneous low pH (pH 3.5) and low water activity (aw = 0.9; 2.5 M NaCl) conditions to Listeria monocytogenes strains ScottA and FW03/0035, and growth permissive temperatures from 25 °C up to 45 °C result in increasingly accelerated inactivation rates. This phenomenon was related to i) increased cell permeability as suggested by ethidium homodimer-1 uptake and ii) de-energization as indicated by rapidly reduced ATP basal levels. Enrichment-based recovery experiments indicated that the stress conditions eventually lead to complete loss of reproductive capacity, possibly corresponding to an irreversible collapse of pH homeostasis. Transcriptomic analyses were used to obtain further insights into the physiology of the inactivation process occurring at 25 °C where inactivation times were more prolonged. QPCR, mRNA decay and microarray experiments revealed transcripts of tufA and other genes become substantially more stable during inactivation resulting from exposure to combined low pH/aw and from non-growth permissive temperature exposure. Genes that appear to be important for initial survival of combined low pH/aw were delineated by K-means clustering of expression data and included an overrepresentation of SigB-activated genes, the overall response of which fades with increasing time of inactivation exposure.

History

Publication title

International Journal of Food Microbiology

Volume

141

Pagination

177-185

ISSN

0168-1605

Department/School

Tasmanian Institute of Agriculture (TIA)

Publisher

Elsevier Science Bv

Place of publication

Po Box 211, Amsterdam, Netherlands, 1000 Ae

Rights statement

Copyright 2010 Elsevier B.V.

Repository Status

  • Restricted

Socio-economic Objectives

Food safety

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