Author(s): B Junker, J Moore, K McLoughlin
Optimization of pilot-scale enzyme production is described for the case of an extracellular protease and an intracellular esterase. Media optimization was conducted to reduce medium costs and to determine the effect of various defined ingredients as well as complex nitrogen sources on enzyme production. Fermentation conditions such as inoculum transfer timing, agitation rate, and cultivation temperature were evaluated for their effect on enzyme production. Broths were harvested via microfiltration, diafiltered, and in the case of the extracellular enzyme, lysed via homogenization. An improvement in enzyme titer and reduction in medium costs for the extracellular protease was realized through replacement of Sabouraud dextrose broth medium with more reasonably priced complex nitrogen sources such as N-Z-amine A. An improvement in enzyme titer and reduction in medium costs for the intracellular esterase was realized by decreasing the amount of malt extract and omitting glycerol from the medium. An improvement in the harvest conditions for both enzymes was realized by using large-lumen-diameter hollow-fiber membranes (2.7 mm) which seemed wide enough to pass clumps of fungal and filamentous bacterial fermentation broth without clogging.