Abstract
The effects of polyethyleneimine, electrolyte concentration and pH on the electrophoretic mobility values for whole yeast, yeast homogenate and borax clarified homogenate were observed. The polyethyleneimine concentration at which there is optimum clarification of the borax-clarified homogenate corresponded to a mobility value of zero. Increased floc size up to the point of zero mobility was obtained by use of polyethyleneimine of larger molecular weight and also higher concentration. The effect of ageing under shear on the size of the flocs was examined and indicated reversibility of break-up at low shear rates while at higher shear rates the flocs were irreversibly broken. Such growth and ageing observations suggest floc formation comprises a two-stage process; the initial formation of primary particles by polymer bridging, and the subsequent formation of larger flocs as these primary particles are brought together by charge neutralisation.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Milburn, P.; Bonnerjea, J.; Hoare, M.; Dunnill, P.: Selective flocculation of nucleic acids, lipids and colloidal particles from a yeast cell homogenate by PEI, and its scale up. Enzyme. Microb. Technol., 12, (1990) 527–532
Salt, D.E.; Hay, S.; Idris, A.; Hoare, M.; Dunnill, P.: Selective flocculation of soluble protein contaminants using polyethyleneimine: a broader study of organisms and polymers. Enzyme. Microb. Technol., 17, 107–113
Horn, D.: Polytheyleneimine — Physicochemical properties and applications. In ‘Polymeric amines and ammonium salts, Ed. Goethals, E.J., Pergamon Press, Oxford, U.K., (1980) 333–353
Lindquist, G.M.; Stratton, R.A.: The role of polyelectrolyte charge density and molecular weight on the adsorption and flocculation of colloidal silica with polyethyleneimine. J. Coll. Int. Sci., 55, (1976) 45–49
Treweek, G.P.; Morgan, J.J.: Polymer flocculation of bacteria: The mechanism of E. coli aggregation by polyethyleneimine. J. Coll. Int. Sci., 60 (1977) 258–273
Bentham, A.C.: Ph.D thesis, University College, London, U.K, (1990)
Mabire, F.; Audebert, R.; Quivoron, C.: Flocculation properties of some water soluble cationic copolymers towards silica suspensions: A semiquantitative interpretation of the role of molecular weight and cationicity through a ‘patchwork’ model. J. Coll. Int. Sci. 97, (1984) 120–136
Michaels, A.S.: Aggregation of suspensions by polyelectrolytes. Ind. Eng. Chem., 46, (1954) 1485–1490
Wilde, P.F.; Dexter, R.W.: Parameters affecting the performance of polyelectrolytes as aids to water clarification. Br. Polym. J., 4, (1972) 239–250
Kitchener, J.A.: Principles of action of polymeric flocculants. Br. Poly. J., 4, (1972) 217–229
Gregory, J.: The effect of cationic polymers on the colloidal stability of latex particles. J. Coll. Int. Sci., 55, (1976) 35–44
Lindstrom, T.; Soremark, C.: Flocculation of cellulosic dispersions in the presence of divalent metal ions. J. Coll. Int. Sci., 55, (1976) 69–72
Gregory, J.: Rates of flocculation of latex particles by cationic polymers. J. Coll. Int. Sci., 42 (1973) 448–456
Ruehrwein, R.A.; Ward, A.: Mechanism of clay aggregation by polyelectrolytes. Soil. Sci. 73, (1952) 485–492
Gregory, J.: Flocculation of polystyrene particles with cationic polyelectrolytes. Trans. Faraday. Soc., 65, (1969) 2260–2268
Kasper, D.R.: Theoretical and experimental investigations of the flocculation of charged particles in aqueous solutions by polyelectrolytes of opposite charge. Ph.D. thesis, California Institute of Technology, Pasadena
Verwey, E.J.W.; Overbeek, J. Th.: In ‘Theory of the stability of lyophobic colloids’, Elsevier, Amsterdam, 1948
Deryagin, B.V.; Landau, L.D.: Theory of the stability of strongly charged lyophobic sols and of the adhesion of strongly charged particles in solutions of electrolytes. Actc. Physicochim. USSR., 14, (1941) 633–638
Black, A.P.; Birkner, F.B.; Morgan, J.J.: Destabilisation of dilute clay suspensions with labelled polymer. J. Amer. Water Works Assn., 57, (1965) 1547–1560
Gregory, J.: Polymeric flocculants. In ‘Chemistry and technology of water soluble polymers’, Ed Finch, C.A., Plenum Press, New York and London, (1983) 307–320
Sikora, M.D.; Stratton, R.A.: The shear stability of flocculated cells. (1981) Tappi., 64, (11), 97–101
Ditter, W.; Eisenlauer, J.; Horn, D.: In ‘The effect of polymers on dispersion properties’ (Ed. Tadros, Th.F.), Academic Press, London, (1982) 323–342
Bonnerjea, J.; Jackson, J.; Hoare, M.; Dunnill, P.: Affinity flocculation of yeast cells debris by carbohydrate specific compounds. Enzyme. Microb. Technol., 10, (1988) 357–360
Amory, D.E.; Rouxhet, P.G.: Surface properties of Saccharomyces cerevisiae: chemical composition, electrostatic charge and hydrophobicity. Biochim. et Biophys. Acta., 938, (1983) 61–70
La Mer, V.K.; Healy, T.W.: Adsorption — flocculation reactions of macromolecules at solid-liquid interfaces. Rev. Pure. Appl. Chem. 13, (1963) 112–133
Cordes, R.: Removal of nucleic acids from bakers yeast. Biochem. Eng. Symp., 16th meeting, (1986) 32–40
Author information
Authors and Affiliations
Additional information
UCL is the Biotechnology and Biological Science Research Council sponsored Advanced Centre for Biochemical Engineering and we are grateful to the Council for financial support.
Rights and permissions
About this article
Cite this article
Salt, D.E., Bentham, A.C., Hay, S. et al. The mechanism of flocculation of a Saccharomyces cerevisiae cell homogenate using polyethyleneimine. Bioprocess Engineering 15, 71–76 (1996). https://doi.org/10.1007/BF00372980
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00372980