title: Assessing physio-macromolecular effects of lactic acid on Zygosaccharomyces bailii cells during microaerobic fermentation.
abstract: 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.
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, Milano 20126, Italy.
authors.forename: Nurzhan
authors.initials: N
authors.lastname: Kuanyshev
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, Milano 20126, Italy Department of Physics, University of Milano-Bicocca, Piazza della Scienza 3, Milano 20126, Italy Consorzio Nazionale Interuniversitario per le Scienze fisiche della Materia (CNISM) UdR Milano-Bicocca, Via R. Cozzi 53, Milano 20126, Italy.
authors.forename: Diletta
authors.initials: D
authors.lastname: Ami
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, Milano 20126, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Signori
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, Milano 20126, Italy.
authors.forename: Danilo
authors.initials: D
authors.lastname: Porro
authors.affiliation: School of Microbiology, University College Cork, Cork, Ireland.
authors.forename: John P
authors.initials: JP
authors.lastname: Morrissey
authors.affiliation: Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, Milano 20126, Italy paola.branduardi@unimib.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Branduardi
mesh_terms: D000693:Anaerobiosis; D019149:Bioreactors / Q000382:microbiology; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D002473:Cell Wall / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D055598:Chemical Phenomena; D003470:Culture Media / Q000737:chemistry; D005285:Fermentation; D005656:Fungal Proteins / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism* / Q000633:toxicity*; D050296:Microbial Viability / Q000187:drug effects*; D011419:Propidium / Q000032:analysis; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared; D013194:Staining and Labeling; D013312:Stress, Physiological; D020068:Zygosaccharomyces / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D019344:Lactic Acid; D011419:Propidium
keywords: FTIR; Zygosaccharomyces bailii; bioreactor; fermentation; lactic acid