Isolation and Some Properties of Amylase from Streptomyces hygroscopicus SF‐1084

Abstract

After screening about three thousands of Streptomyces strains from soils, a strain of Streptomyces hygroscopicus SF‐1084, which gave the highest amylase production was isolated and some properties of the amylase were studied. Amylase production media were examined and a medium which consisted of glucose 2%, corn starch 5.5%, corn meal 1%, wheat germ 0.5%, soy bean meal 1.4%, KH2PO4 0.2% adjusted to pH 7.0 was used to produce the amylase. Amylase production by 30 l jar fermenter was reached at 1500 u/ml in 110 h culture. The amylase was purified from broth filtrate by the method of ammonium sulfate precipitation, DEAE‐sephadex A‐50 column chromatography and Sephadex G‐150 gelfiltration to get single band on a polyacrylamide disc gel electrophoresis. It is shown that the SF‐1084 amylase produced 88% maltose from amylose and 80% maltose from amylopectin in 48 h saccharification. From the pattern of blue value and reducing value, the amylase is supposed to have endogenous action on starch and the activity is not inhibited by PCNB (pentachloronitrobenzene); the SF‐1084 amylase does not belong to β‐amylase. The optimum pH of the amylase was 5 to 6 and the optimum temperature was 50 to 55 °C. The amylase was fairly thermostable and the residual activity after incubation at 90 °C for 15 min and 100 °C for 15 min were revealed more than 50% and 30% respectively.

Purification and Characterization of a Thermostable Raw Starch Digesting Amylase from aStreptomycessp. Isolated in a Milling Factory

“…The activities of the enzyme solution showed 0.13 unit/ml on highamylose starch at 60 C, and 0.42 unit/ml on gelatinized starch at 50 C. The enzyme showed sufficient activity at 70 C. The thermostability of this enzyme is an advantage in industrial applications, because moderate heating higher than 60 C is indispensable in the starch saccharifying industry to prevent microbial contamination. Although a number of raw starch digesting amylases from Streptomyces have been reported, [1][2][3]10) and the effect of temperature on enzymes were examined (Table 5), the enzyme in our investigation is one of the most thermostable and thermoactive raw starch digesting amylases from Streptomyces, the same as from S. hygroscopicus SF-1084. 1,12) The reaction rate on various substrates of the enzyme was examined.…”

“…Although a number of raw starch digesting amylases from Streptomyces have been reported, [1][2][3]10) and the effect of temperature on enzymes were examined (Table 5), the enzyme in our investigation is one of the most thermostable and thermoactive raw starch digesting amylases from Streptomyces, the same as from S. hygroscopicus SF-1084. 1,12) The reaction rate on various substrates of the enzyme was examined. Raw wheat, rice, and waxy rice starches were digested more rapidly than raw sweet potato, tapioca, or potato starches by the enzyme.…”

“…Starch hydrolyzing enzymes are widely distributed in species of Streptomyces, [1][2][3][4][5][6][7][8][9][10] and some of them can attack and hydrolyze raw starch granules. [1][2][3]10) Such raw starch digesting amylases are commercially important enzymes useful in industry, since they save much energy in gelatinizing starchy materials.…”

“…[1][2][3]10) Such raw starch digesting amylases are commercially important enzymes useful in industry, since they save much energy in gelatinizing starchy materials. 11) Especially the maltooligosaccharide producing amylases are very important for the industrial conversion of raw starch into sugars for food, beverages, and fermentation, 12,13) and have been reported from Streptomyces that exhibited highly interesting properties, especially in its end product.…”

“…1,12) On the other hand, the purified enzyme from S. thermocyaneoviolaceus IFO-14271 is maltogenic and considered to be an extremely active raw starch digesting amylase. 10) Recently, we isolated a highly raw starch utilizing microbe from mud in a milling factory, and found that the strain produced a thermostable, maltogenic raw starch digesting amylase.…”