Efficient flotation of yeast cells grown in batch culture

Abstract

A fast flotation assay was used to select new floating yeast strains. The flotation ability did not seem to be directly correlated to total extracellular protein concentration of the culture. However, the hydrophobicity of the cell was definitely correlated to the flotation capacity. The Saccharomyces strains (FLT strains) were highly hydrophobic and showed an excellent flotation performance in batch cultures without additives (flotation agents) and with no need for a special flotation chamber or flotation column. A stable and well‐organized structure was evident in the dried foam as shown by scanning electron microscopy which revealed its unique structure showing mummified cells (dehydrated) attached to each other. The attachment among the cells and the high protein concentration of the foams indicated that proteins might be involved in the foam formation. The floating strains (strains FLT) which were not flocculent and showed no tendency to aggregate, were capable of growing and producing ethanol in a synthetic medium containing high glucose concentration as a carbon source. The phenomenon responsible for flotation seems to be quite different from the flocculation phenomenon. © 1996 John Wiley & Sons, Inc.

Identification and characterization of a very long-chain fatty acid elongase gene in the methylotrophic yeast, Hansenula polymorpha

“…Broth culture of H. polymorpha cells shows poor sedimentation ability due to the high hydrophobicity of the cell wall (Palmieri et al, 1996;deSousa et al, 2003). We found, however, that cells of the Hpelo1Δ disruptant settled down rapidly in a glucose-rich broth culture after being left at room temperature.…”

Strategy for selection of methods for separation of bioparticles from particle mixtures

“…In these applications, aqueous two-phase systems (Andrews et al, 1995;Asenjo et al, 1991;Guereca et al, 1994;HeywoodWaddington et al, 1986;Kula, 1986Kula, , 1993Walker and Lyddiatt, 1999) and other liquid-liquid systems (Borbas et al, 2001;Dennison and Lovrien, 1997;Hoeben et al, 2004;Jauregi et al, 2001Jauregi et al, , 2002Kiss et al, 1998;Pike and Denisson, 1989;Tan and Lovrien, 1972) were used to capture the desired products in the interface between the two liquids. In addition, air flotation which makes use of the adsorption of particles and/or molecules to air bubbles that rise in the liquid phase due to buoyancy, has been applied for the recovery of whole cells (Bahr and Schügerl, 1992;De Dousa et al, 2003;Gahr and Schügerl, 1992;Gaudin, 1975;Wang, 1966, 1967;Kalyuzhnyi et al, 1965;Palmieri et al, 1996;Sadowski and Golab, 1991;Tybussek et al, 1994;Vlaski et al, 1996;Wang et al, 1994). In all of these examples, interfaces are used to capture the product, but this does not necessarily mean that separation is accomplished solely with the interfacial tension force.…”

Intragenic repeat expansions control yeast chronological aging

“…In this model, the dynamic repeat expansions and contractions of HPF1 may serve as a life style switch, allowing rapid shifts between buoyant and sedentary life styles in evolution as dictated by fluctuating, opposing selection pressures. We note that the biochemical properties of the yeast cell wall have been linked to buoyancy (DeSousa et al 2003; Fidalgo et al 2006;Palmieri, Greenhalf, and Laluce 1996), albeit through hydrophobicity rather than by serine/threonine induced hydrogen bond formation with water molecules.The HPF1 induced shift to a buoyant life style with concomitant life span shortening due to methionine, lipid and purine oxidation has no immediate parallel in multicellular organisms.…”