Details

Autor(en) / Beteiligte

• Branco, Patrícia
• Viana, Tiago
• Albergaria, Helena
• Arneborg, Nils

Titel

Antimicrobial peptides (AMPs) produced by Saccharomyces cerevisiae induce alterations in the intracellular pH, membrane permeability and culturability of Hanseniaspora guilliermondii cells

Ist Teil von

• International journal of food microbiology, 2015-07, Vol.205 (C), p.112-118

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2015

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• Saccharomyces cerevisiae produces antimicrobial peptides (AMPs) during alcoholic fermentation that are active against several wine-related yeasts (e.g. Hanseniaspora guilliermondii) and bacteria (e.g. Oenococcus oeni). In the present study, the physiological changes induced by those AMPs on sensitive H. guilliermondii cells were evaluated in terms of intracellular pH (pHi), membrane permeability and culturability. Membrane permeability was evaluated by staining cells with propidium iodide (PI), pHi was determined by a fluorescence ratio imaging microscopy (FRIM) technique and culturability by a classical plating method. Results showed that the average pHi of H. guilliermondii cells dropped from 6.5 (healthy cells) to 5.4 (damaged cells) after 20min of exposure to inhibitory concentrations of AMPs, and after 24h 77.0% of the cells completely lost their pH gradient (∆pH=pHi−pHext). After 24h of exposure to AMPs, PI-stained (dead) cells increased from 0% to 77.7% and the number of viable cells fell from 1×105 to 10CFU/ml. This means that virtually all cells (99.99%) became unculturable but that a sub-population of 22.3% of the cells remained viable (as determined by PI staining). Besides, pHi results showed that after 24h, 23% of the AMP-treated cells were sub-lethally injured (with 0<∆pH<3). Taken together, these results indicated that this subpopulation was under a viable but non-culturable (VBNC) state, which was further confirmed by recuperation assays. In summary, our study reveals that these AMPs compromise the plasma membrane integrity (and possibly also the vacuole membrane) of H. guilliermondii cells, disturbing the pHi homeostasis and inducing a loss of culturability. •AMPs affect the plasma membrane and, apparently, also the vacuole membranes of Hanseniaspora guilliermondii cells.•The pHi homeostasis was completely lost in 77% of cells after 24h of incubation with the AMPs.•Intracellular pH decreased immediately (after 20min) upon AMPs addition.