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.: Home > Nature and Science > 2012 > Volume 10 Number 5 > Sikander Ali† and Ikram-ul-Haq

Enhanced production of calcium citrate by a 2-deoxy-D-glucose resistant mutant strain of Aspergillus niger using two factorial design

Sikander Ali† and Ikram-ul-Haq
Institute of Industrial Biotechnology (IIB), GC University Lahore, Pakistan E-mail: alisbiotech@yahoo.com
Abstract :

Over hundred isolates of the filamentous fungus Aspergillus niger were examined for calcium citrate productivity under submerged culture conditions in 1-L Erlenmeyer flasks. The isolate IIB-46 was selected for improvement through ultraviolet (UV) light-induced mutagenesis. Among viable mutants, strain 19 exhibited the best citrate productivity, and it was subjected to ethyl methane sulphonate (EMS) treatment. The mutant was cultured overnight and plated on 2-deoxy-D-glucose-PDA medium. A mutant strain EMS-6 gave the highest citrate production (86.48 g/l) which varied significantly (p≤0.05) from that of the wild type. The optimal citrate synthase activity (28 U/ml/min) was achieved at the optimal fermentation conditions with 26.5 g/l DCM. Maximum glucose consumption was found to be 130 g/l (over 90 % substrate conversion rate). Citrate productivity was increased over 28 % when the process parameters, incubation period (72 h), initial pH (6.5), glucose as carbon source (15 %), inoculum size (1.875×106 CFU/ml) and corn steep liquor (CSL) as nitrogen source (0.5 %) were optimized using a 2-factorial Plackett-Burman design. The model terms were highly significant (HS) thus suggesting the potential commercial utility of the mutant (df=3~0.0218).

Keywords :
Aspergillus niger; Calcium citrate fermentation; Mutagenesis; 2-Factorial design; 2-deoxy-D-glucose

Date Deposited : 16 May 2016 20:07

Last Modified : 16 May 2016 20:07

Official URL: http://www.sciencepub.net/nature/

Volume 10, Number 5, - 2012 , ISSN 1545-0740

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