Properties and Application of a Thermostable Maltogenic Amylase Produced by a Strain of Bacillus Modified by Recombinant‐DNA Techniques

Abstract

During a screening programme for amylase producing microorganisms a strain of Bacillus was isolated which produced a maltogenic amylase which had possible industrial potential. Unlike the microbial 0-amylases from B. cereus, B. rnegateriurn, B. polymyxa and B. circulans this enzyme was characterized by being stable at 60 -70 "C at pH 4.5.-5.5. Unfortunately the microorganism proved to be difficult to cultivate. Using recombinant-DNA techniques it was possible to transfer the gene, which coded for the enzyme, to a host organism which was easier to cultivate, thus making industrial production a viable proposition. The enzyme is suitable for producing high maltose syrups from liquefied starch. When used together with an amylopectin debranching enzyme such as pullulanase, more than 75% maltose can be obtained at 30% D.S. Eigenschaften und Verwendung einer thermostabilen, maltosebildenden Amylase aus einem durch DNA-Rekombinationstechnik modifizierten Bacillus-Stamm. Im Laufe einer systematischen Suche nach Amylase erzeugenden Mikroorganismen wurde ein Bucillus-Stamm isoliert, der eine Maltose bildende Amylase von moglichem industriellem Interesse produzierte. Im Gegensatz zu den mikrobiellen 0-Amylasen von B. cereus, B. megaterium, B. polyrnyxa und B. circulans ist dieses Enzym durch seine Stabilitat bei 60 -70°C und pH-Werten von 4,5 -5,5 gekennzeichnet. Bedauerlicherweise zeigten sich bei der Ziichtung des Mikroorganismus grol3ere Schwierigkeiten. Mit der DNA-Rekombinationstechnik war es aber moglich, das enzymbildende Gen auf einen Wirtsorganismus zu ubertragen, der einfacher zu ziichten war und eine industrielle Produktion ermoglichen konnte. Das neue Enzym ist fur die Herstellung von Hoch-Maltose-Sirupen aus verfliissigter Starke geeignet. Wenn es in Kombination mit einem Amylopektin entzweigenden Enzym wie Pullulanase verwendet wird, ist ein Maltosegehalt uber 75% i. TS erreichbar (bei 30% TS in der Losung). starch/starke 36 (1984) Nr. 12, S. [405][406][407][408][409][410][411]

Amylase action pattern on starch polymers

“…They hydrolyse α-(1-4) glycosidic bonds of the starch polymers, thereby liberating α-maltose (Outtrup & Norman 1984;Christophersen et al 1998). Their precise mode of action is not completely clear.…”

Starch‐Processing Enzymes

“…This enzyme is a very efficient producer of maltose and was first launched on the market as Maltogenase. 15,16 It was the first commercial enzyme to be produced using a genetically modified microorganism. It turned out that this thermostable amylase is active during the baking process and prevents staling to a major extent.…”

Novel Maltose-producing Amylase fromBacillus megateriumG-2

“…Outtrop and Norman 7 ) reported that 1) the maltose-producing amylase from Bacillus stearothermophilus produced a-maltose by hydrolysing amylose, amylopectin and related glucose polymers through on exo-mechanism, 2) the enzyme was not inhibited by sulfhydryl reagents, 3) the enzyme exhibited an endoaction, hydrolyzing cyclodextrin to maltose and glucose, and 4) the enzyme completely hydrolyzed maltotriose to maltose and glucose. Characteristics 1) to 4) are completely different from those of fj-amylase, and characteristics 2), 3) and 4) are also different from those of the maltose-producing amylase of B. megaterium 0-2.…”

“…-5) The other maltose-producting amylase is a kind of a-amylase which yields amaltose by splitting the a-l,4-glucosidic linkages in starch through an endo-mechanism. Some amylases of this type, such as those from Streptomyces hydroscopicus 6 ) and Bacillus stearothermophilus, 7) can produce maltose in higher yields from starch than f3-amylase does. However, these amylases also produce glucose, maltotriose and other oligosaccharides at the same time.…”