Intracellular pH of Mycobacterium avium subsp. paratuberculosis following exposure to antimicrobial compounds monitored at the single cell level

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Francesca Gaggìa, Dennis Sandris Nielsen, Bruno Biavati, Henrik Siegumfeldt

Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent of Johne's disease; moreover, it seems to be implicated in the development of Crohn's disease in humans. In the present study, fluorescence ratio imaging microscopy (FRIM) was used to assess changes in intracellular pH (pH(i)) of one strain of MAP after exposure to nisin and neutralized cell-free supernatants (NCSs) from five bacteriocin-producing lactic acid bacteria (LAB) with known probiotic properties. The evaluation of pH(i) by FRIM provides information about the physiological state of bacterial cells, bypassing the long and problematic incubations needed for methods relying upon growth of MAP such as determination of colony forming units. The FRIM results showed that both nisin and the cell-free supernatant from Lactobacillus plantarum PCA 236 affected the pH(i) of MAP within a few hours. However, monitoring the population for 24h revealed the presence of a subpopulation of cells probably resistant to the antimicrobial compounds tested. Use of nisin and bacteriocin-producing LAB strains could lead to new intervention strategies for the control of MAP based on in vivo application of probiotic cultures as feed additives at farm level.

Original languageEnglish
JournalInternational Journal of Food Microbiology
Volume141
Pages (from-to)S188-S192
Number of pages5
ISSN0168-1605
DOIs
Publication statusPublished - 2010

ID: 32330253