This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Yun, J. Articles by Ryu, S. Search for Related Content PubMed PubMed Citation Articles by Yun, J. Articles by Ryu, S. Agricola Articles by Yun, J. Articles by Ryu, S.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, December 2004, p. 7229-7235, Vol. 70, No. 12
0099-2240/04/$08.00+0     DOI: 10.1128/AEM.70.12.7229-7235.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Characterization of a Novel Amylolytic Enzyme Encoded by a Gene from a Soil-Derived Metagenomic Library

Jiae Yun,¹ Seowon Kang,¹ Sulhee Park,¹ Hyunjin Yoon,¹ Myo-Jeong Kim,² Sunggi Heu,³ and Sangyeol Ryu^1*

Department of Food Science and Technology, School of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National University, Seoul,¹ Biohealth Products Research Center and Food Science Institute, School of Food and Life Science, Inje University, Gimhae,² Plant Pathology Division, National Institute of Agricultural Science and Technology, Suwon, South Korea³

Received 9 February 2004/ Accepted 12 July 2004

It has been estimated that less than 1% of the microorganisms in nature can be cultivated by conventional techniques. Thus, the classical approach of isolating enzymes from pure cultures allows the analysis of only a subset of the total naturally occurring microbiota in environmental samples enriched in microorganisms. To isolate useful microbial enzymes from uncultured soil microorganisms, a metagenome was isolated from soil samples, and a metagenomic library was constructed by using the pUC19 vector. The library was screened for amylase activity, and one clone from among approximately 30,000 recombinant Escherichia coli clones showed amylase activity. Sequencing of the clone revealed a novel amylolytic enzyme expressed from a novel gene. The putative amylase gene (amyM) was overexpressed and purified for characterization. Optimal conditions for the enzyme activity of the AmyM protein were 42°C and pH 9.0; Ca²⁺ stabilized the activity. The amylase hydrolyzed soluble starch and cyclodextrins to produce high levels of maltose and hydrolyzed pullulan to panose. The enzyme showed a high transglycosylation activity, making -(1, 4) linkages exclusively. The hydrolysis and transglycosylation properties of AmyM suggest that it has novel characteristics and can be regarded as an intermediate type of maltogenic amylase, -amylase, and 4--glucanotransferase.

---

* Corresponding author: Department of Food Science and Technology, School of Agricultural Biotechnology, Seoul National University, San 56-1, Shillim-dong, Kwanak-gu, Seoul 151-742, South Korea. Phone: 82 2 880 4856. Fax: 82 2 873 5095. E-mail: sangryu{at}snu.ac.kr.

---

Applied and Environmental Microbiology, December 2004, p. 7229-7235, Vol. 70, No. 12
0099-2240/04/$08.00+0     DOI: 10.1128/AEM.70.12.7229-7235.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Waschkowitz, T., Rockstroh, S., Daniel, R. (2009). Isolation and Characterization of Metalloproteases with a Novel Domain Structure by Construction and Screening of Metagenomic Libraries. Appl. Environ. Microbiol. 75: 2506-2516 [Abstract] [Full Text]