African Journal of

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12269

Full Length Research Paper

Influence of nitrogen sources on production of b-galactosidase by Aspergillus niger

M. Siddique Awan1*, Shahzad Akbar Khan1, Z. U. Rehman1, Azhar Saleem2, S. M. Rana3 and M. I. Rajoka3,4
  1Faculty of Agriculture, Rawalakot, University Azad Jammu and Kashmir, Pakistan. 2Department of Statistics, AJ and K University Muzaffarabad AK, Pakistan. 3GC University, Faisalabad Pakistan. 4National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan.
Email: [email protected]

  •  Accepted: 26 February 2010
  •  Published: 17 May 2010



The study was undertaken to enhance the production of b-galactosidase using five organic nitrogen sources with wheat bran as a substrate under solid state fermentation. The microbial source Aspergillus niger and its DG-resistant mutant that were grown in medium with initial pH of 5.5 in 250 ml flasks at 30°C for 144 h and sample was harvested after every 24 h and analysed for substrate consumption, cell mass formation and enzyme production. All the nitrogen sources, ammonium sulphate, corn steep liquor, diammonium phosphate, fish meal and urea showed significant results. However, higher values of enzyme activity of 168.0 and 371.15 IU/l/h, parent and mutant, respectively, was obtained from sample in which corn steep liquor was used as a nitrogen source as compared to control (73.1 and 176.3 IU/l/h in parent and mutant, respectively). The effect of nitrogen sources was also found significant in both the organisms but higher in mutant organism (2.2 fold). It is concluded that enzyme production enhanced 2.7 fold by use of suitable production medium under optimum cultural conditions and that the mutant derivative of A. niger can be exploited for hyper production of this enzyme.


Key words: Aspergillus niger, wheat bran, corn steep liquor, b-galactosidase.


DG, Deoxyglucose; p-NPG, p-nitrophenyl β-D-galactopyranoside;PDA, potato-dextrose agar media; SSF, solid-state fermentation; CLS, corn steep liquor; DAP, diammonium phosphate; BSA, bovine serum albumin; LSD, least significant difference; β –gal, β- galactopyranoside.