African Journal of

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12412

Full Length Research Paper

Kinetics of endoglucanase and cellobiohydrolase production by parent and mutant derivative of moderately thermotolerant Bacillus subtilis GQ 301542 on optimized medium

Nagina Rafique1, Muhammad Siddique Awan1*, Habib Ahmed Rathore1, Dilnawaz Ahmed Gardezi3, Maqsood Ahmad4, Mohsin Tariq2 and Muhammad Ibrahim Rajoka2,5  
1Department of Food Technology, Faculty of Agriculture, Rawalakot, University of Azad Jammu and Kashmir (AJ and K), Pakistan. 2National Institute of Biotechnology and Genetic Engineering, Faisalabad-38000, Pakistan. 3Department of Plant Breeding and Molecular Genetics, Faculty of Agriculture, Rawalakot, University of Azad Jammu and Kashmir,  AJ and K, Pakistan. 4Department of Horticulture, Faculty of Agriculture, Rawalakot, University of Azad Jammu and Kashmir (AJ and K), Pakistan. 5GC University, Faisalabad-38000, Pakistan.
Email: [email protected]

  •  Accepted: 16 September 2010
  •  Published: 01 November 2010



A moderately thermotolerant bacterial strain was isolated from the hot spring of Tatta Pani (AJ and K) Pakistan and was designated as Bacillus subtilis strain GQ 301542 after biochemical, morphological and 16S rDNA sequence analysis. This strain and its catabolite repression resistant mutant CRM197 were utilized for the study of different production kinetic parameters of both endoglucanase and cellobiohydrolase. Time course study on one monomeric (glucose), one dimeric (maltose) and two polymeric substrates (α-cellulose and wheat straw) was carried out at different time intervals (4 - 28 h, after each 4 h) for determining the maximum enzyme productivity on a particular substrate. Maximum rate of endoglucanase production by the mutant (53.1 IU/L/h) was significantly (P = 0.0007) higher than that (23.7 IU/L/h of the parental organism  following their growth on glucose in Dubos salts medium while the optimum product yields (Yp/s) was calculated as 69.0 IU/g S (parent) and 82.3 IU/g S (mutant) for cellobiohydrolase production. Deoxy-D-glucose resistant mutant was significantly (p = 0.03 to 0.0007) improved over its parental strain with respect to some substrate consumption and all product formation parameters and can easily degrade cellulosic biomass for production of fermentable carbohydrates.


Key words: Cellobiohydrolase, endoglucanase, thermotolerant, Bacillus subtilis.


Abbreviations: µ, Specific growth rate (h-1); Qs, rate of subs/h); Yp/s, product yield (IU/g S utilized); Yp/x,  specific yield of enzyme produstrate (S) consumption (g S/L/h); Qx, rate of cell mass formation (g cells/L/h); qs, specific rate of substrate consumption (g S/g cells/h); Yx/s, g (cells)/ g (S) consumed; Qp, rate of product formation (IU/L/h); qp, specific rate of enzyme production (IU/g cellction (IU/g cells); CBH, cellobiohydrolase; CMC, carboxymethyl cellulose; CMCase, carboxymethyl cellulose.