Bioconversion of unmodified native starches by Pseudomonas stutzeri maltotetraohydrolase: effect of starch type

Maltooligosaccharides including maltotetraose (G₄) have unique uses in biochemical, clinical, pharmaceutical, and food applications. G₄ productivity utilizing a G₄-producing amylase from Pseudomonas stutzeri in a membrane recycle bioreactor (MRB) was compared using four kinds of unmodified starches differing in the ration of amylose to amylopectin and the amylopectin chain lengths, and also one modified soluble starch. The specific activity of the enzyme used for the MRB system was 21.5 units/mg protein. The product purity using a native corn starch was 20.0% higher than that using a modified soluble starch in an MRB of bench-top scale. Four kinds of unmodified native corn starches were shown to be better substrates than the modified soluble starch considering all the criteria of product purity, production rate, and total product output. Correspondence to: Gun-Jo Woo