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Continuous Production of Isomalto-oligosaccharides by Thermo-inactivated Cells of Aspergillus niger J2 with Coarse Perlite as an Immobilizing Material

Huang, Zhihua, Li, Zhihong, Su, Yongjian, Zhu, Yongfeng, Zeng, Wei, Chen, Guiguang, Liang, Zhiqun
Applied biochemistry and biotechnology 2018 v.185 no.4 pp. 1088-1099
Aspergillus niger, alpha-glucosidase, diatomaceous earth, enzyme activity, filtration, glycosylation, industry, malt, maltose, mixing, pH, perlite, syrups, temperature
The coarse perlite 40–80 mesh was selected as an immobilizing material and put into a packed bed reactor (PBR) to continuously convert maltose to isomalto-oligosaccharides (IMOs). The PBR was prepared by mixing the thermo-inactivated cells (TIC) from Aspergillus niger J2 strain with the coarse perlite, then the mixture was put into an overpressure-resistant column. Compared with diatomite 40–80 mesh and thin perlite 80–120 mesh in PBR, coarse perlite was chosen as the best filtration aid, when the ratio of coarse perlite versus TIC was 1:1. The thermal and pH stability of the free and immobilized TIC and the optimum conditions for the transglycosylation reactions were determined. The results show that approximately 75 and 82% and 87 and 91% of α-glucosidase activity were reserved for free and immobilized TIC at temperatures from 30 to 60 °C and pH from 3.00 to 7.00 for 12 h, respectively. With 30% malt syrup under the conditions of 50 °C and pH 4.00, a mini-scale packed bed reactor (Mi-PBR) and medium-scale packed bed reactor (Me-PBR) could continuously produce IMO over 25 and 34 days with the yield of effective IMO (eIMO) ≥ 35% and total IMO (tIMO) ≥ 50%, respectively. The strategy of mixing the coarse perlite with TIC in PBR is a novel approach to continuously produce IMO and has great application potential in industry.