Degradation of Starch Granules by Alpha‐Amylase of Streptomyces precox NA‐273

Abstract

The action of purified α‐amylase of Streptomyces precox NA‐273 on starch granules of normal maize and potato was studied. The hydrolysis was followed by measuring total soluble carbohydrates and glucose released. Patterns of degradation were observed by scanning electron microscopy (SEM). The main soluble product was maltose, small amounts of glucose and higher oligosaccharides were always observed. By SEM, attack started small pits on the surfaces of maize starch granules, pits increased in number and in size, and pores penetrated into the inner portions of the granules toward the center. The enzyme seemed to degrade the inner portion of starch granules better than the well‐known general α‐amylases.

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

“…The scanning electron microscopy observations of partially digested raw corn starch granules by the enzyme showed many holes of different sizes, depths, and widths on the surface. Similar action patterns have been reported, 2,3,10,12,[21][22][23][24][25][26][27][28] and almost all of them were by the action of -amylase. On the contrary, raw starch digesting glucoamylase 10,21,22,27,28) produced small pits of homogeneous size.…”

“…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.…”

“…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.…”

Some Enzyme Properties of Raw Starch Digesting Amylases fromStreptomyces sp. No. 4

“…Starch hydrolyzing enzymes are widely distributed in species of Streptomyces [1][2][3][4][5][6][7][8][9], and some of them can attack and hydrolyze raw starch granules [1][2][3], with the release of maltose as the predominant product. Such enzymes are useful for the industrial conversion of raw starch into sugars for fermentation [10].…”