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Effect of pH on potassium metabisulphite biocidic activity against yeast and human cell cultures
Laura Corte1, Luca Roscini1, Claudia Zadra2
1Dipartimento Biologia Applicata - Microbiologia, Università degli Studi di Perugia, Via Borgo 20 Giugno, 74, I-06121 Perugia, Italy.
Abstract:
Potassium metabisulphite (PMB) is a common antimicrobial additive in the food industry. In aqueous solutions, PMB leads to complex equilibria according to its concentration, pH and temperature, and different chemical species can be present. In winemaking, PMB is used at low pH, suggesting that the biocidic activity is exerted by sulphur dioxide while, in other applications, it is employed at higher pH values with little if any dissociation. This observation leads to the question of which chemical form is biologically active. For this reason, Saccharomyces cerevisiae cells were subjected to PMB solutions at different pH values and analysed with a Fourier transform infrared spectroscopy (FTIR)-based bioassay, to assess the entity and the type of stress. Cell viability was determined and compared to the metabolomics (FTIR) stress indices, which revealed that the metabolomics fingerprint was an effective description of the cell health state. GC-MS metabolite profiles were obtained to describe (in detail) the changes caused by PMB in the fatty acids region. Human dermal fibroblasts (HDF) were also subjected to PMB stress at pH 7.0 and analysed with the FTIR protocol, in order to compare the response spectra of yeast and human cell cultures.
Insights
Potassium metabisulphite (PMB) antimicrobial activity depends on pH. FTIR bioassays reveal distinct stress responses in yeast and human cells, correlating with viability and identifying active chemical species.
Area of Science:
- Food science and technology
- Microbiology
- Biochemistry
Background:
- Potassium metabisulphite (PMB) is a widely used antimicrobial additive in food processing.
- The chemical speciation and biological activity of PMB in aqueous solutions are complex, varying with concentration, pH, and temperature.
- Understanding which chemical form of PMB is biologically active is crucial for optimizing its application.
Purpose of the Study:
- To investigate the biologically active chemical species of potassium metabisulphite (PMB) at different pH levels.
- To assess the cellular stress response of Saccharomyces cerevisiae to PMB using Fourier transform infrared spectroscopy (FTIR).
- To compare the FTIR-based stress profiles of yeast and human dermal fibroblasts (HDF) exposed to PMB.
Main Methods:
- Yeast (Saccharomyces cerevisiae) and human dermal fibroblast (HDF) cells were exposed to PMB solutions across a range of pH values.
- Fourier transform infrared spectroscopy (FTIR) was employed as a bioassay to analyze cellular stress responses.
- Cell viability assays and Gas Chromatography-Mass Spectrometry (GC-MS) for fatty acid profiling were conducted.
Main Results:
- FTIR-based metabolomics fingerprinting effectively described the cellular health state under PMB stress.
- Distinct stress response spectra were observed for yeast and HDF cells exposed to PMB.
- GC-MS analysis detailed PMB-induced alterations in cellular fatty acid profiles.
Conclusions:
- The study highlights FTIR as a valuable tool for assessing cellular stress and health in response to chemical agents like PMB.
- Different chemical species of PMB induce specific stress responses in different cell types.
- The findings contribute to a better understanding of PMB's antimicrobial mechanisms and safe application in food and potentially other industries.
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