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Plant Pathol J. 2017 Jun;33(3):318-328. doi: 10.5423/PPJ.FT.01.2017.0022. Epub 2017 Jun 1.

Purification and Characterization of a Major Extracellular Chitinase from a Biocontrol Bacterium, Paenibacillus elgii HOA73.

Author information

1
College of Life and Resource Science, Dankook University, Cheonan 31116, Korea.
2
Department of Plant Medicine, Suncheon National University, Suncheon 57922, Korea.
3
Institute of Environmentally-Friendly Agriculture, Chonnam National University, Gwangju 61186, Korea.

Abstract

Chitinase-producing Paenibacillus elgii strain HOA73 has been used to control plant diseases. However, the antimicrobial activity of its extracellular chitinase has not been fully elucidated. The major extracellular chitinase gene (PeChi68) from strain HOA73 was cloned and expressed in Escherichia coli in this study. This gene had an open reading frame of 2,028 bp, encoding a protein of 675 amino acid residues containing a secretion signal peptide, a chitin-binding domain, two fibronectin type III domains, and a catalytic hydrolase domain. The chitinase (PeChi68) purified from recombinant E. coli exhibited a molecular mass of approximately 68 kDa on SDS-PAGE. Biochemical analysis indicated that optimum temperature for the actitvity of purified chitinase was 50ºC. However, it was inactivated with time when it was incubated at 40ºC and 50ºC. Its optimum activity was found at pH 7, although its activity was stable when incubated between pH 3 and pH 11. Heavy metals inhibited this chitinase. This purified chitinase completely inhibited spore germination of two Cladosporium isolates and partially inhibited germination of Botrytis cinerea spores. However, it had no effect on the spores of a Colletotricum isolate. These results indicate that the extracellular chitinase produced by P. elgii HOA73 might have function in limiting spore germination of certain fungal pathogens.

KEYWORDS:

Botrytis cinerea; Paenibacillus elgii; antifungal activity; extracellular chitinase; heterologous expression

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