title: Production, Optimization, and Characterization of Organic Solvent Tolerant Cellulases from a Lignocellulosic Waste-Degrading Actinobacterium, Promicromonospora sp. VP111.
abstract: High costs of natural cellulose utilization and cellulase production are an industrial challenge. In view of this, an isolated soil actinobacterium identified as Promicromonospora sp. VP111 showed potential for production of major cellulases (CMCase, FPase, and β-glucosidase) utilizing untreated agricultural lignocellulosic wastes. Extensive disintegration of microcrystalline cellulose and adherence on it during fermentation divulged true cellulolytic efficiency of the strain. Conventional optimization resulted in increased cellulase yield in a cost-effective medium, and the central composite design (CCD) analysis revealed cellulase production to be limited by cellulose and ammonium sulfate. Cellulase activities were enhanced by Co(+2) (1 mM) and retained up to 60 °C and pH 9.0, indicating thermo-alkaline tolerance. Cellulases showed stability in organic solvents (25 % v/v) with log P ow  ≥ 1.24. Untreated wheat straw during submerged fermentation was particularly degraded and yielded about twofold higher levels of cellulases than with commercial cellulose (Na-CMC and avicel) which is especially economical. Thus, this is the first detailed report on cellulases from an efficient strain of Promicromonospora that was non-hemolytic, alkali-halotolerant, antibiotic (erythromycin, kanamycin, rifampicin, cefaclor, ceftazidime) resistant, multiple heavy metal (Mo(+6) = W(+6) > Pb(+2) > Mn(+2) > Cr(+3) > Sn(+2)), and organic solvent (n-hexane, isooctane) tolerant, which is industrially and environmentally valuable.
authors.affiliation: Applied Microbiology and Biotechnology Laboratory, Department of Botany, University of Delhi, Delhi, 110 007, India.
authors.forename: Lebin
authors.initials: L
authors.lastname: Thomas
authors.affiliation: Applied Microbiology and Biotechnology Laboratory, Department of Botany, University of Delhi, Delhi, 110 007, India.
authors.forename: Hari
authors.initials: H
authors.lastname: Ram
authors.affiliation: Applied Microbiology and Biotechnology Laboratory, Department of Botany, University of Delhi, Delhi, 110 007, India.
authors.forename: Alok
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Applied Microbiology and Biotechnology Laboratory, Department of Botany, University of Delhi, Delhi, 110 007, India. vpsingh_biology@rediffmail.com.
authors.forename: Ved Pal
authors.initials: VP
authors.lastname: Singh
mesh_terms: D039903:Actinobacteria / Q000737:chemistry / Q000201:enzymology*; D000383:Agriculture; D001673:Biodegradation, Environmental; D044602:Cellulases / Q000096:biosynthesis* / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D005285:Fermentation; D008031:Lignin / Q000737:chemistry*; D012997:Solvents / Q000633:toxicity
chemical_list: D012997:Solvents; C036909:lignocellulose; D000431:Ethanol; D008031:Lignin; D044602:Cellulases
keywords: Actinobacteria; Alkali halo tolerant; Lignocellulose; Organic solvent tolerant; Promicromonospora sp. VP111