Bacillus cereus NY-14, which was isolated from soil and identified, could digest soluble starch and effectively produce maltopentaose. Three enzymes, an extracellular α-amylase and two cell-bound α-glucosidases, are responsible for the production and later disappearance of maltopentaose in a culture medium containing soluble starch. So the culture conditions for thev production and the properties of the three enzymes were investigated. The extracellular α-amylase was induced by maltooligosaccharides or amylaceous polysaccharides. The action pattern of this amylase on amylaceous polysaccharides was unique in that the predominant product was maltopentaose. Cell-bound α-glucosidases I and II were induced by maltose, α-Glucosidases I and II are classified as a maltase and isomaltase (oligo-1, 6-glucosidase [EC 3.2.1.10]), respectively. The mechanism of maltopentaose production by B. cereus NY-14 seems to be as follows, (1) When B. cereus NY-14 is cultured in a medium containing soluble starch, it secretes an extracellular α-amylase which digests soluble starch to produce maltopentaose as the main product. Maltose is also formed, which to induce two cell-bound α-glucosidases. (2) α-Glucosidase I can hydrolyze maltose, maltotriose and maltotetraose produced through the action of α-amylase, to glucose, which can be easily taken into the cells. α-Glucosidase I shows only weak activity toward maltopentaose, so the specific accumulation of maltopentaose occurs at an early stage of cultivation. a-Glucosidase II plays a part in the formation of glucose by acting, together with α-glucosidase I, on limit dextrins produced through the action of aamylase. (3) At a relatively slower rate, however, a-glucosidase I can hydrolyze maltopentaose, so that the accumulated maltopentaose gradually disappears from the culture medium as the cultivation proceeds. 2-Chloro-4-nitrophenyl β-maltopentaoside was synthesized chemically with maltopentaose and used as the substrate for determination of serum a-amylase.
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