Tracking Yeast Metabolism and the Crabtree Effect in Real Time via CO2 Production using Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS)

• Published in: Journal of biotechnology 2020-01, Vol.308, p.63-73
• Main Authors: Ahmed, M. Rizwan, Doyle, Nicholas, Connolly, Cathal, McSweeney, Seán, Krüse, Jacob, Morrissey, John, Prentice, Michael B., Fitzpatrick, Dara
• Format: Article
• Language: English
• Subjects: Acoustics; Crabtree effect; Metabolism; Spectroscopy; Viability and vitality; Yeast
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/j.jbiotec.2019.11.016

Yeast activity in solution can be quantified by its production of Carbon Dioxide which affects the compressibility of the solution which can be tracked acoustically with a microphone. Yeast is found to respond predictably to a fixed amount of glusose. [Display omitted] •BARDS is a rapid method for real-time analysis of CO2 production by yeast cells via the Crabtree Effect.•Yeast strains can be differentiated by real-time CO2 production profiling.•BARDS detects intracellular v extra-cellular timelines for CO2 production.•BARDS can determine cellular CO2 gaseous production using the Crawford Equation.•BARDS can detect metabolic pathway switching depening on the carbon source bolus used. In this study, a new approach to measure metabolic activity of yeast via the Crabtree effect is described. BARDS is an analytical technique developed to aid powder and tablet characterisation by monitoring changes in the compressibility of a solvent during solute dissolution. It is a rapid and simple method which utilises a magnetic stir bar to mix added solute and induce the acoustic resonance of a vessel containing a fixed volume of solvent. In this study it is shown that initiation of fermentation in a yeast suspension, in aqueous buffer, is accompanied by reproducible changes in the frequency of induced acoustic resonance. These changes signify increased compressibility of the suspension due to CO2 release by the yeast. A simple standardised BARDS protocol reveals yeast carbon source preferences and can generate quantitative kinetic data on carbon source metabolism which are characteristic of each yeast strain. The Crawford-Woods equation can be used to quantify total gaseous CO2 produced by a given number of viable yeast when supplied with a fixed amount of carbon source. This allows for a value to be calculated for the amount of gaseous CO2 produced by each yeast cell. The approach has the potential to transform the way in which yeast metabolism is tracked and potentially provide an orthogonal or surrogate method to determining viability, vitality and attenuation measurements in the future.