Purification, characterization and cloning of a thermotolerant isoamylase produced from Bacillus sp. CICIM 304
- 556 Downloads
A novel thermostable isoamylase, IAM, was purified to homogeneity from the newly isolated thermophilic bacterium Bacillus sp. CICIM 304. The purified monomeric protein with an estimated molecular mass of 100 kDa displayed its optimal temperature and pH at 70 °C and 6.0, respectively, with excellent thermostability between 30 and 70 °C and pH values from 5.5 to 9.0. Under the conditions of temperature 50 °C and pH 6.0, the K m and V max on glycogen were 0.403 ± 0.018 mg/mg and 0.018 ± 0.001 mg/(min mg), respectively. Gene encoding IAM, BsIam was identified from genomic DNA sequence with inverse PCRs. The open reading frame of the BsIam gene was 2,655 base pairs long and encoded a polypeptide of 885 amino acids with a calculated molecular mass of 101,155 Da. The deduced amino acid sequence of IAM shared less than 40 % homology with that of microbial isoamylase ever reported, which indicated it was a novel isoamylase. This enzyme showed its obvious superiority in the industrial starch conversion process.
KeywordsBacillus sp. Thermostable isoamylase Purification Enzyme properties Cloning
This study was granted by China-South Africa Joint project (2009DFA31300), the ‘863’ program (2011AA100905), Program for New Century Excellent Talents in University (NCET-11-0665), Innovative Research Team of Jiangsu Province, the Priority Academic Program Development of Jiangsu Higher Education Institutions and the 111 Project (No. 111-2-06).
- 4.Ara K, Saeki K, Ito S (1993) Purification and characterization of an alkaline isoamylase from an alkalophilic strain of Bacillus. J Gen Microbiol 139(4):781–786Google Scholar
- 5.Benedict SR (1909) A reagent for the detection of reducing sugars. J Biol Chem 5(5):485–487Google Scholar
- 7.Chen JH, Chen ZY, Chow TY, Chen JC, Tan ST, Hsu WH (1090) Nucleotide sequence and expression of the isoamylase gene from an isoamylase-hyperproducing mutant, Pseudomonas amyloderamosa JD210. Biochim Biophys Acta 1087(3):309–315Google Scholar