Characterisation of intracellular gas bubbles in Saccharomyces

[摘要] The yeast fermentation process is well established. However, until recently nosign of intracellular gas bubbles had been reported. A paradigm shift emanatedwhen intracellular gas bubbles were discover using various microscopy techniquesthereby resolving the missing link between CO2 production and eventual releasefrom the cells. The lack of membranes around the gas bubbles served as adistinguishing feature of the bubbles. However, there had been other non-envelopedstructure that had been reported as either lipid droplets or vacuole fragments. Thisstudy, using organelle-specific fluorescent probes, shows that intracellular gasbubbles, lipid droplets and vacuole fragments are separate inclusions that can coexistin the cell. Considering that intracellular gas bubbles compress and deformorganelles, coupled to the fact that yeast cells have an internal pressure of 2.1 MPaand that pressurised CO2 has been reported to have adverse effects onmicroorganisms warranted an investigation into the effect of intracellular gas bubbleson cell function. This study concludes that the formation of intracellular gas bubblesdid not have a negative effect on mitochondrial activity. The observation offermenting S. pastorianus cells (more gas bubbles) having lower lipid content thanrespiring cells (few gas bubbles) indicates that the gas bubble formation plays a rolein controlling the buoyant cell density of fermenting in this strain. This suggests thatthe influence of bubble formation may be limited and strain dependent.

[发布机构] University of the Free State