Production of mold amylases in submerged culture.

During recent years many new and extended uses have been developed for fungal enzymes. Prominent among these are applications in the fields of food manufacturing, textile processing, and in the manufacture of malt beverages and industrial alcohol. Although certain microorganisms are capable of elaborating amylases when grown under submerged conditions either aerobically (Waldmann, 1942) or anaerobically (Hockenhull and Herbert, 1945), industrial production methods generally involve cultivation on the surface of unagitated liquid or semisolid substrates. Exceptions are the "amylo" process (Owen, 1933) and a modified amylo process (Erb and Hildebrandt, 1946), in which selected strains of Rhizopus or Mucor are grown under submerged, aerobic conditions to saccharify grain mashes prior to alcoholic fermentation. More commonly, as in the production of mold bran (Underkofler, et al., 1939; Boyer and Underkofler, 1945) and bacterial amylases (Beckord et al., 1945, 1946), media are incubated in shallow layers in closed vessels or in open trays. Attempts to adapt these microorganisms to deep tank conditions to produce comparable yields of amylase have been unsuccessful. The submerged culture method of producing amylases would have definite advantages when the product could be employed directly without concentration or purification as, for example, in the alcoholic fermentation of grain and in the manufacture of sugars and dextrins from starch. With these applications in mind a survey was made of a large number of molds to determine their ability to synthesize starch-hydrolyzing enzymes when cultured under submerged conditions. The present report deals with (1) the results of this survey of fungi, (2) the factors affecting the elaboration of amylases by promising strains, and (3) the substitution of mold amylase thus produced for distillers' malt. Pilot plant studies have been conducted with some of the promising strains disclosed herein, and the results of these experiments will be reported at a later date.