Intrinsic fermentation kinetics of lactose in acidogenic biofilms

• Published in: Biotechnology and bioengineering 1993-02, Vol.41 (4), p.479-488
• Main Authors: Yu, J. (University of British Columbia, Vancouver, British Columbia, Canada), Pinder, K.L
• Format: Article
• Language: English
• Subjects: ACIDE ACETIQUE; ACIDE BUTYRIQUE; ACIDE LACTIQUE; ACIDE PROPIONIQUE; ACIDO ACETICO; ACIDO BUTIRICO; ACIDO LACTICO; ACIDO PROPIONICO; acidogenesis kinetics; ANAEROBIOSE; ANAEROBIOSIS; biofilm; Biological and medical sciences; BIOSINTESIS; BIOSYNTHESE; Biotechnology; DIFFUSION; DIFUSION; FERMENTACION; FERMENTATION; Fundamental and applied biological sciences. Psychology; LACTOSA; LACTOSE; LACTOSERUM; mass transfer resistance; METABOLISME DES GLUCIDES; METABOLISMO DE CARBOHIDRATOS; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; MICROORGANISME; MICROORGANISMOS; SUERO DE LA LECHE; TRANSFERENCIA DE MASA; TRANSFERT DE MASSE
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.260410412

The intrinsic fermentation kinetics of lactose in acidogenic biofilms were investigated in situ in a continuous flow fermentor at 35 degrees C and pH 4.6. The external and internal mass transfer resistances to lactose molecules from bulk solution to inside the biofilms were experimentally minimized or eliminated in a thin biofilm and recycled medium. In a chemically defined culture medium, the immobilized acidogens converted lactose mainly to acetate and butyrate; the minor products included ethanol, propionate, lactate, and hydrogen. The utilization rate of lactose, as a function of lactose concentration in the fermentor, can be described by a Michaelis-Menten equation, as can the formation rates of acetate, butyrate, and ethanol. The production rates of propionate and lactate had a linear relationship with lactose concentration under the experimental conditions. The low pH (4.6) of culture medium could depress the formation of propionate, an intermediate which is most difficultly digested by acetogenic bacteria located in the second fermentor in a two-phase process. Production rate of acetate quickly reached a constant, and additional utilization of lactose produced more butyrate and other minor products