title: Molecular characterization of a beta-1,4-endoglucanase from an endophytic Bacillus pumilus strain.
abstract: Endophytes comprise mainly microorganisms that colonize inner plant tissues, often living with the host in a symbiotic manner. Several ecological roles have been assigned to endophytic fungi and bacteria, such as antibiosis to phytopathogenic agents and plant growth promotion. Nowadays, endophytes are viewed as a new source of genes, proteins and biochemical compounds that may be used to improve industrial processes. In this study, the gene EglA was cloned from a citrus endophytic Bacillus strain. The EglA encodes a beta-1,4-endoglucanase capable of hydrolyzing cellulose under in vitro conditions. The predicted protein, EglA, has high homology to other bacterial cellulases and shows a modular structure containing a catalytic domain of the glycosyl hydrolase family 9 (GH9) and a cellulose-binding module type 3 (CBM3). The enzyme was expressed in Escherichia coli, purified to homogeneity, and characterized. EglA has an optimum pH range of 5-8, and remarkable heat stability, retaining more than 85% activity even after a 24-h incubation at pH 6-8.6. This characteristic is an important feature for further applications of this enzyme in biotechnological processes in which temperatures of 50-60 degrees C are required over long incubation periods.
authors.affiliation: Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Av. Pádua Dias 11, Piracicaba, SP, 13418-900, Brazil. lima@cttmar.univali.br
authors.forename: André O S
authors.initials: AO
authors.lastname: Lima
authors.forename: Maria C
authors.initials: MC
authors.lastname: Quecine
authors.forename: Maria H P
authors.initials: MH
authors.lastname: Fungaro
authors.forename: Fernando D
authors.initials: FD
authors.lastname: Andreote
authors.forename: Walter
authors.initials: W
authors.lastname: Maccheroni
authors.forename: Welington L
authors.initials: WL
authors.lastname: Araújo
authors.forename: Márcio C
authors.initials: MC
authors.lastname: Silva-Filho
authors.forename: Aline A
authors.initials: AA
authors.lastname: Pizzirani-Kleiner
authors.forename: João L
authors.initials: JL
authors.lastname: Azevedo
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D002480:Cellulase / Q000737:chemistry* / Q000378:metabolism*; D003001:Cloning, Molecular; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D011487:Protein Conformation; D013696:Temperature
chemical_list: D002480:Cellulase