Cloning and expression of a novel α-galactosidase fromLactobacillus amylolyticusL6 with hydrolytic and transgalactosyl properties

作者：Fei, Yongtao; Jiao, WenJuan; Wang, Ying; Liang, Jinglong; Liu, Gongliang^*; Li, Li^*

来源：PLoS One, 2020, 15(7): e0235687.

DOI：10.1371/journal.pone.0235687

• LACTOBACILLUS-AMYLOLYTICUS L6
• PURIFICATION
• OLIGOSACCHARIDES

Lactobacillus amylolyticusL6, a gram-positive amylolytic bacterium isolated from naturally fermented tofu whey (NFTW), was able to hydrolyze raffinose and stachyose for the production of alpha-galactosidase. The cell-free extract ofL.amylolyticusL6 was found to exhibit glycosyltransferase activity to synthesize alpha-galacto-oligosaccharides (GOS) with melibiose as substrate. The coding genes of alpha-galactosidase were identified in the genome ofL.amylolyticusL6. The alpha-galactosidase (AglB) was placed into GH36 family by amino acid sequence alignments with other alpha-galactosidases from lactobacilli. The optimal reaction conditions of pH and temperature for AglB were pH 6.0 and 37 degrees C, respectively. Besides, potassium ion was found to improve the activity of AglB while divalent mercury ion, copper ion and zinc ion displayed different degrees of inhibition effect. Under the optimum reaction condition, AglB could catalyze the synthesis of GOS with degree of polymerization (DP) >= 5 by using 300 mM melibiose concentration as substrate. The maximum yield of GOS with (DP) >= 3 could reach 31.56% (w/w). Transgalactosyl properties made AglB a potential candidate for application in the production of GOS.

• 单位
  广东省农业科学院; 仲恺农业工程学院