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Acidophilic β-Galactosidase from Aspergillus niger AHU7120 with Lactose Hydrolytic Activity Under Simulated Gastric Conditions

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Title: Acidophilic β-Galactosidase from Aspergillus niger AHU7120 with Lactose Hydrolytic Activity Under Simulated Gastric Conditions
Authors: Saburi, Wataru Browse this author →KAKEN DB
M. Ueno, Hiroshi Browse this author
Matsui, Hirokazu Browse this author →KAKEN DB
Mori, Haruhide Browse this author →KAKEN DB
Keywords: β-galactosidase
lactose intolerance
Aspergillus niger
Issue Date: 20-May-2014
Publisher: 日本応用糖質科学会
Journal Title: Journal of Applied Glycoscience
Volume: 61
Issue: 2
Start Page: 53
End Page: 57
Publisher DOI: 10.5458/jag.jag.JAG-2013_011
Abstract: Acidophilic β-galactosidase is a useful enzyme as digestive supplement used to alleviate symptoms of lactose intolerance. Aspergilli are the source of several acidophilic β-galactosidases that retain enzymatic activity under gastric conditions. In this study, we investigated the extracellular acidophilic β-galactosidase activity of six Aspergillus niger strains, AHU7104, AHU7120, AHU7217, AHU7294, AHU7295 and AHU7296; A. niger AHU7120 was selected as an enzyme source. β-Galactosidase from A. niger AHU7120 (AnBGal) was purified from culture supernatant. Its N-terminal sequence was identical to that of An01g12150, which belongs to the glycoside hydrolase family 35, from A. niger CBS 513.88. The DNA sequence of AnBGal was identical to An01g12150. Recombinant AnBGal (rAnBGal) harboring yeast α-factor signal sequence was expressed in Pichia pastoris, and 21.9 mg of purified rAnBGal with 129 U/mg of enzyme activity was isolated from 200 mL of culture supernatant. Native and recombinant AnBGal enzymes showed similar pH optima, pH stability, and kinetics for p-nitrophenyl β-D-galactopyranoside and lactose; rAnBGal showed slightly lower thermal stability than the native enzyme. Lactose in milk was rapidly degraded by rAnBGal at higher pH values (range, 2.0‒3.5), consistent with the pH optimum of AnBGal. We estimated that 3.5 μM AnBGal may degrade ≥ 66% of lactose before gastric half-emptying of ingested milk. These data indicate that AnBGal may help alleviate symptoms of lactose intolerance.
Type: article (author version)
Appears in Collections:農学院・農学研究院 (Graduate School of Agriculture / Faculty of Agriculture) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 佐分利 亘

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