Identification and characterization of novel transglycosylating a-glucosidase from Aspergillus neoniger.

Kumar, S. and Basu, A. and Anu Appaiah, K. A. and Gnanesh Kumar, B. S. and Mutturi, S. (2020) Identification and characterization of novel transglycosylating a-glucosidase from Aspergillus neoniger. Journal of Applied Microbiology. ISSN 1364-5072

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Abstract

Aim: Aspergillus niger is well established for secreting a-glucosidase having transglycosylation activity, which is used as processing aid for synthesis of isomaltooligosaccharides. The present study focuses on identification and characterization of a non-niger Aspergillus isolate and its gene conferring strong transglycosylation activity. Methods and Results: The soil isolate was identified as Aspergillus neoniger belonging to Aspergillus section Nigri using ITS (internal transcribed spacer) and b-tubulin analysis. The sequence analysis of gene responsible for aglucosidase synthesis revealed significant nucleotide variations when compared to other Aspergillus species. Molecular docking studies using the homology model revealed the presence of threonine at 694 subsite position instead of asparagine as in case of A. niger’s a-glucosidase. The enzyme was purified to several fold using DEAE Sepharose-CL6B column and on SDS-PAGE analysis, it was found to be 145 kDa. MS/MS analysis of the purified enzyme validated the presence of threonine at 694 position. Commercial a-glucosidase (Transglucosidase L ‘Amano’) derived from A. niger and the a-glucosidase from isolate were compared for transglycosylation activity using constant test conditions. a-glucosidase from the isolate produced 27�4% higher panose when compared to that of commercial enzyme. Moreover, the rate of secondary hydrolysis of panose is much lower in case of the isolate’s enzyme. Conclusions: Fungal isolate A. neoniger was characterized, and its gene conferring a-glucosidase activity was established for strong transglycosylation activity having higher panose yields. Significance and Impact of the Study: To the best of our knowledge, this is the first report to establish a variant of a-glucosidase having strong transglycosylation activity from A. neoniger strain. We have demonstrated that this enzyme when used as processing aid could improve panose significantly, which is a potential prebiotic. Also, the sequence analysis established in our studies could provide pointers for directed evolution of this enzyme to further improve transglycosylation activity

Item Type:	Article
Uncontrolled Keywords:	a-glucosidase, Aspergillus neoniger, isomaltooligosaccharides, prebiotic, transglycosylation
Subjects:	600 Technology > 08 Food technology > 09 Food Microbiology
Divisions:	Dept. of Biochemistry Fermentation Technology and Bioengineering
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	05 Oct 2020 06:27
Last Modified:	05 Oct 2020 06:27
URI:	http://ir.cftri.res.in/id/eprint/14493

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