High purity prebiotic isomalto-oligosaccharides production by cell associated transglucosidase of isolated strain Debaryomyces hansenii SCY204 and selective fermentation by Saccharomyces cerevisiae SYI065

Abstract

An efficient recycling method was used to develop the continuous production of high purity isomalto-oligosaccharides (IMOs) by cell associated transglucosidase of a novel strain, D. hansenii from maltose and selective fermentation by S. cerevisiae. The most potent transglucosidase producer was screened, isolated and identified as Debaryomyces hansenii using LSU region sequencing. Parameters optimization studies were investigated using whole cells of D. hansenii (∼4023 units L−1 α-glucosidase activity) from 10 L fermenter to increase the transglucosidase activity through biotransformation. IMOs was continuously synthesized by reusing the cell biomass (6 %) in a 3 L bioreactor using microfiltration membrane system with 30 % maltose concentration under controlled temperature of 34 °C in an average of 12 h for 5 cycles. The obtained low purity IMOs (67 %) was further incubated with cell pellet of isolated strain Saccharomyces cerevisiae (4 %, w/v) in 3 L bioreactor for 1 h to utilize glucose completely without affecting the product to obtain high purity IMOs by recycling method. This novel study using these yeasts, was found to utilize more than 98 % maltose with higher conversion efficiency for production of IMOs with >91 % purity, 79 % yield and highest productivity of 198.79 g L-1.h which was confirmed by HPLC.