title: Purification and biochemical properties of a thermostable, haloalkaline cellulase fromBacillus licheniformisAMF-07 and its application for hydrolysis of different cellulosic substrates to bioethanol production.
abstract: A thermophilic strain AMF-07, hydrolyzing carboxymethylcellulose (CMC) was isolated from Kerman hot spring and was identified asBacillus licheniformisbased on 16S rRNA sequence homology. The carboxymethylcellulase (CMCase) enzyme produced by theB. licheniformiswas purified by (NH4)2SO4 precipitation, ion exchange and gel filtration chromatography. The purified enzyme gave a single band on SDS- PAGE with a molecular weight of 37 kDa. The CMCase enzyme was highly active and stable over broad ranges of temperature (40-80ºC), pH (6.0-10.0) and NaCl concentration (10-25%) with an optimum at 70ºC, pH 9.0 and 20% NaCl, which showed excellent thermostable, alkali-stable and halostable properties. Moreover, it displayed high activity in the presence of cyclohexane (134%) and chloroform (120%). Saccharification of rice bran and wheat bran by the CMCase enzyme resulted in respective yields of 24 and 32 g L-1 reducing sugars. The enzymatic hydrolysates of rice bran were then used as the substrate for ethanol production bySaccharomyces cerevisiae. Fermentation of cellulosic hydrolysate usingS. cerevisiae, reached maximum ethanol production about 0.125 g g-1 dry substrate (pretreated wheat bran). Thus, the purified cellulase fromB. licheniformisAMF-07 utilizing lignocellulosic biomass could be greatly useful to develop industrial processes.
authors.affiliation: Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Azadian
authors.affiliation: Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Arastoo
authors.initials: A
authors.lastname: Badoei-Dalfard
authors.affiliation: Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Abdolhamid
authors.initials: A
authors.lastname: Namaki-Shoushtari
authors.affiliation: Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Hassanshahian
keywords: Bioethanol; Cellulosic hydrolysate; Characterization; Purification