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Listeria innocua and Lactobacillus delbrueckii subsp. bulgaricus employ different strategies to cope with acid stress

Citation

Shabala, L and McMeekin, TA and Budde, BB and Siegumfeldt, H, Listeria innocua and Lactobacillus delbrueckii subsp. bulgaricus employ different strategies to cope with acid stress, International Journal of Food Microbiology, 110, (1) pp. 1-7. ISSN 0168-1605 (2006) [Refereed Article]

DOI: doi:10.1016/j.ijfoodmicro.2006.01.026

Abstract

Responses of Listeria innocua and Lactobacillus delbrueckii subsp. bulgaricus to a rapid change in extracellular pH (pHex) from pHex 6 to a range of concentrations down to pHex 3.0 were examined, using HCl and lactic acid (LA) as acidulants. A new fluorescent probe 5-(and-6)-carboxy-2′, 7′-dichlorofluorescein diacetate succinimidyl ester (CDCFDA-SE) was employed that enabled reliable measurements of intracellular pH (pHi) to a minimum pHi of 4.0. Changes in pHi and H+ fluxes from immobilised bacteria were measured using fluorescence ratio imaging microscopy (FRIM) and a non-invasive ion flux measuring technique (MIFE), respectively. L. innocua maintained a relatively constant pHi of 5.5-6.1 at pHex 4 and 5 via H+ extrusion. In contrast, L. delbrueckii subsp. bulgaricus progressively lowered pHi towards pHex over the entire pHex range examined. The type of acidulant used influenced pH regulation with both pHi and H+-fluxes being more severely affected by LA compared to HCl. Overall, our data demonstrated different adaptive strategies in these two bacteria. While L. innocua expels protons to maintain a constant pHi, L. delbrueckii subsp. bulgaricus allows proton entry after acidic treatment so that pHi follows pHex. © 2006 Elsevier B.V. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Microbiology
Research Field:Microbial Ecology
Objective Division:Health
Objective Group:Public Health (excl. Specific Population Health)
Objective Field:Food Safety
Author:Shabala, L (Dr Lana Shabala)
Author:McMeekin, TA (Professor Thomas McMeekin)
ID Code:33048
Year Published:2006
Web of Science® Times Cited:29
Deposited By:Agricultural Science
Deposited On:2006-08-01
Last Modified:2007-04-17
Downloads:0

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