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Applied and Environmental Microbiology, January 2005, p. 363-370, Vol. 71, No. 1
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.1.363-370.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Cloning of Beauveria bassiana Chitinase Gene Bbchit1 and Its Application To Improve Fungal Strain Virulence

Weiguo Fang, Bo Leng, Yuehua Xiao, Kai Jin, Jincheng Ma, Yanhua Fan, Jing Feng, Xingyong Yang, Yongjun Zhang, and Yan Pei*

Biotechnology Research Center, Southwest Agricultural University, Beibei, Chongqing, People's Republic of China

Received 31 May 2004/ Accepted 29 August 2004

Entomopathogenic fungi can produce a series of chitinases, some of which act synergistically with proteases to degrade insect cuticle. However, chitinase involvement in insect fungus pathogenesis has not been fully characterized. In this paper, an endochitinase, Bbchit1, was purified to homogeneity from liquid cultures of Beauveria bassiana grown in a medium containing colloidal chitin. Bbchit1 had a molecular mass of about 33 kDa and pI of 5.4. Based on the N-terminal amino acid sequence, the chitinase gene, Bbchit1, and its upstream regulatory sequence were cloned. Bbchit1 was intronless, and there was a single copy in B. bassiana. Its regulatory sequence contained putative CreA/Crel carbon catabolic repressor binding domains, which was consistent with glucose suppression of Bbchit1. At the amino acid level, Bbchit1 showed significant similarity to a Streptomyces avermitilis putative endochitinase, a Streptomyces coelicolor putative chitinase, and Trichoderma harzianum endochitinase Chit36Y. However, Bbchit1 had very low levels of identity to other chitinase genes previously isolated from entomopathogenic fungi, indicating that Bbchit1 was a novel chitinase gene from an insect-pathogenic fungus. A gpd-Bbchit1 construct, in which Bbchit1 was driven by the Aspergiullus nidulans constitutive promoter, was transformed into the genome of B. bassiana, and three transformants that overproduced Bbchit1 were obtained. Insect bioassays revealed that overproduction of Bbchit1 enhanced the virulence of B. bassiana for aphids, as indicated by significantly lower 50% lethal concentrations and 50% lethal times of the transformants compared to the values for the wild-type strain.

* Corresponding author. Mailing address: Biotechnology Research Center, Southwest Agricultural University, Beibei, Chongqing 400716, People's Republic of China. Phone: 86-23-68251883. Fax: 86-23-68250515. E-mail: peiyan{at}swau.edu.cn.

Applied and Environmental Microbiology, January 2005, p. 363-370, Vol. 71, No. 1
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.1.363-370.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Zhang, Y., Zhao, J., Fang, W., Zhang, J., Luo, Z., Zhang, M., Fan, Y., Pei, Y. (2009). Mitogen-Activated Protein Kinase hog1 in the Entomopathogenic Fungus Beauveria bassiana Regulates Environmental Stress Responses and Virulence to Insects. Appl. Environ. Microbiol. 75: 3787-3795 [Abstract] [Full Text]  
  • Fang, W., Pei, Y., Bidochka, M. J. (2007). A regulator of a G protein signalling (RGS) gene, cag8, from the insect-pathogenic fungus Metarhizium anisopliae is involved in conidiation, virulence and hydrophobin synthesis. Microbiology 153: 1017-1025 [Abstract] [Full Text]  
  • Fan, Y., Fang, W., Guo, S., Pei, X., Zhang, Y., Xiao, Y., Li, D., Jin, K., Bidochka, M. J., Pei, Y. (2007). Increased Insect Virulence in Beauveria bassiana Strains Overexpressing an Engineered Chitinase. Appl. Environ. Microbiol. 73: 295-302 [Abstract] [Full Text]  


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