EVALUATION OF COLUMN FLOTATION IN THE DOWNSTREAM PROCESSING OF FERMENTATION PRODUCTS - RECOVERY OF A GENETICALLY-ENGINEERED ALPHA-AMYLASE

Flotation is a simple, inexpensive, and versatile unit operation with a largely unexplored potential in biotechnology. There is a general la ck of research concerning biotechnological applications in this area, especially in the recovery of fermentation products. Moreover, the few reports in the literature do not consider the modem concept of column flotation as practiced in the mineral industry. We report herein the application of column flotation for the recovery of a Bacillus stearot hermophilus alpha-amylase expressed in Escherichia coli by the use of a food-grade polymer, (hydroxypropyl)methylcellulose (HPMC), and ammon ium sulfate. First, the enzyme was removed from the liquid phase by pa rtition to a salted-out HPMC phase. The enzyme-containing polymer floc s were then floated from the liquid. Recovery of active enzyme was as high as 90%, with throughput as high as 94 m3/(h.m2). The floatability of the enzyme from a periplasmic extract was higher than extracellula r enzyme in the broth due to the presence of depressors of molecular w eight lower than 10 000 in the broth.