Molecular characterization of a beta-1,4-endoglucanase from an endophytic Bacillus pumilus strain.
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.
Lima
André O S
AO
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
Quecine
Maria C
MC
Fungaro
Maria H P
MH
Andreote
Fernando D
FD
Maccheroni
Walter
W
Araújo
Welington L
WL
Silva-Filho
Márcio C
MC
Pizzirani-Kleiner
Aline A
AA
Azevedo
João L
JL
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
D002480:Cellulase