Expression and characterization of a glucose-tolerant ß-1,4-glucosidase with wide substrate specificity from Cytophaga hutchinsonii.
Appl Microbiol Biotechnol
; 101(5): 1919-1926, 2017 Mar.
Article
em En
| MEDLINE
| ID: mdl-27822737
ABSTRACT
Cytophaga hutchinsonii is a gram-negative bacterium that can efficiently degrade crystalline cellulose by a novel strategy without cell-free cellulases or cellulosomes. Genomic analysis implied that C. hutchinsonii had endoglucanases and ß-glucosidases but no exoglucanases which could processively digest cellulose and produce cellobiose. In this study, BglA was functionally expressed in Escherichia coli and found to be a ß-glucosidase with wide substrate specificity. It can hydrolyze pNPG, pNPC, cellobiose, and cellodextrins. Moreover, unlike most ß-glucosidases whose activity greatly decreases with increasing length of the substrate chains, BglA has similar activity on cellobiose and larger cellodextrins. The K m values of BglA on cellobiose, cellotriose, and cellotetraose were calculated to be 4.8 × 10-2, 5.6 × 10-2, and 5.3 × 10-2 mol/l, respectively. These properties give BglA a great advantage to cooperate with endoglucanases in C. hutchinsonii in cellulose degradation. We proposed that C. hutchinsonii could utilize a simple cellulase system which consists of endoglucanases and ß-glucosidases to completely digest amorphous cellulose into glucose. Moreover, BglA was also found to be highly tolerant to glucose as it retained 40 % activity when the concentration of glucose was 100 times higher than that of the substrate, showing potential application in the bioenergy industry.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Celulose
/
Beta-Glucosidase
/
Cytophaga
/
Escherichia coli
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article