Pullulanase: Role in Starch Hydrolysis and Potential Industrial Applications

Abstract

The use of pullulanase (EC 3.2.1.41) has recently been the subject of increased applications in starch-based industries especially those aimed for glucose production. Pullulanase, an important debranching enzyme, has been widely utilised to hydrolyse the α-1,6 glucosidic linkages in starch, amylopectin, pullulan, and related oligosaccharides, which enables a complete and efficient conversion of the branched polysaccharides into small fermentable sugars during saccharification process. The industrial manufacturing of glucose involves two successive enzymatic steps: liquefaction, carried out after gelatinisation by the action of α-amylase; saccharification, which results in further transformation of maltodextrins into glucose. During saccharification process, pullulanase has been used to increase the final glucose concentration with reduced amount of glucoamylase. Therefore, the reversion reaction that involves resynthesis of saccharides from glucose molecules is prevented. To date, five groups of pullulanase enzymes have been reported, that is, (i) pullulanase type I, (ii) amylopullulanase, (iii) neopullulanase, (iv) isopullulanase, and (v) pullulan hydrolase type III. The current paper extensively reviews each category of pullulanase, properties of pullulanase, merits of applying pullulanase during starch bioprocessing, current genetic engineering works related to pullulanase genes, and possible industrial applications of pullulanase.

Amylase Producing Bacillus megaterium T04 Isolated in Rach Lang Stream of Vietnam

“…Glucoamylase can hydrolyze starch by cutting both α-1,4-glycosidic linkages and α-1,6-glycosidic linkages. Nevertheless, pullulanase can cut α-1,6-glycosidic linkages only (Hii et al, 2012). Interestingly, the enzyme showed 174.7 IU/mL and 0.2 IU/mL in medium containing wheat and rice, respectively.…”

Marine enzymes and food industry: insight on existing and potential interactions

“…These enzymes are often combined with glucoamylase for efficient saccharification of starch, thus allowing for high glucose yield (Hii et al, 2012). Given the operational conditions for starch processing, referred to in the section dedicated to amylases, thermo tolerant enzymes are looked after Marine sources have been naturally tapped as providers of such pullulanases.…”

“…The authors did not evaluate the operational stability of the enzyme, although they clearly established that α-1,6 glycosidic activity was predominant in the enzyme preparation. This is not always the case, since debranching enzymes may also present α-1,4 glycosidic activity, thus being termed pullulanases type II, or amylopullulanases, and proving particularly useful in starch hydrolysis (Hii et al, 2012). This is the case of a hyperthermophilic amylopullulunase produced by Thermococcus hydrothermalis, an archaeon isolated from a deep-sea hydrothermal vent (Gantelet and Duchiron, 1998).…”

Engineering of Escherichia coli to facilitate efficient utilization of isomaltose and panose in industrial glucose feedstock

“…Industrial glucose feedstock is prepared from starch, a polysaccharide composed of glucose units linked together by α-1,4 and α-1,6 glycoside bonds, by means of enzymatic hydrolysis (Martin and Smith 1995;Hii et al 2012). Complete hydrolysis of starch into glucose adds significant cost; therefore, most commercially available glucose feedstock is processed incompletely (Gokarn et al 2014).…”

“…Complete hydrolysis of starch into glucose adds significant cost; therefore, most commercially available glucose feedstock is processed incompletely (Gokarn et al 2014). Because of incomplete enzymatic hydrolysis and/or reverse reactions, the glucose feedstock contains significant amounts of maltose (Hii et al 2012;Gokarn et al 2014;Hassan et al 1998;Crabb and Shetty 1999;Sierkes and Svensson 1992;Takasaki 1988;Chaplin and Bucke 1994). If microorganisms used for fermentation cannot metabolize these saccharides, valuable carbohydrates would be wasted.…”