Assessing physio-macromolecular effects of lactic acid on Zygosaccharomyces bailii cells during microaerobic fermentation

• Published in: FEMS yeast research 2016-08, Vol.16 (5), p.fow058
• Main Authors: Kuanyshev, Nurzhan, Ami, Diletta, Signori, Lorenzo, Porro, Danilo, Morrissey, John P., Branduardi, Paola
• Format: Article
• Language: English
• Subjects: Anaerobiosis; Bioreactors - microbiology; Cell Membrane - chemistry; Cell Membrane - drug effects; Cell Membrane - physiology; Cell Wall - chemistry; Cell Wall - drug effects; Cell Wall - physiology; Chemical Phenomena; Culture Media - chemistry; Fermentation; Fungal Proteins - chemistry; Hydrogen-Ion Concentration; Lactic Acid - metabolism; Lactic Acid - toxicity; Microbial Viability - drug effects; Propidium - analysis; Protein Conformation; Spectroscopy, Fourier Transform Infrared; Staining and Labeling; Stress, Physiological; Zygosaccharomyces - drug effects; Zygosaccharomyces - growth & development; Zygosaccharomyces - physiology
• ISSN: 1567-1364; 1567-1364
• DOI: 10.1093/femsyr/fow058

The ability of Zygosaccharomyces bailii to grow at low pH and in the presence of considerable amounts of weak organic acids, at lethal condition for Saccharomyces cerevisiae, increased the interest in the biotechnological potential of the yeast. To understand the mechanism of tolerance and growth effect of weak acids on Z. bailii, we evaluated the physiological and macromolecular changes of the yeast exposed to sub lethal concentrations of lactic acid. Lactic acid represents one of the important commodity chemical which can be produced by microbial fermentation. We assessed physiological effect of lactic acid by bioreactor fermentation using synthetic media at low pH in the presence of lactic acid. Samples collected from bioreactors were stained with propidium iodide (PI) which revealed that, despite lactic acid negatively influence the growth rate, the number of PI positive cells is similar to that of the control. Moreover, we have performed Fourier Transform Infra-Red (FTIR) microspectroscopy analysis on intact cells of the same samples. This technique has been never applied before to study Z. bailii under this condition. The analyses revealed lactic acid induced macromolecular changes in the overall cellular protein secondary structures, and alterations of cell wall and membrane physico-chemical properties. We describe how lactic acid, a biobased chemical platform, induces relevant phenotypic and macromolecular changes in Zygosaccharomyces bailii, an organic acid-resistant yeast exploitable for industrial processes of production. Graphical Abstract Figure. We describe how lactic acid, a biobased chemical platform, induces relevant phenotypic and macromolecular changes in Zygosaccharomyces bailii, an organic acid-resistant yeast exploitable for industrial processes of production.