PJB-2021-248
Strain improvement of Aspergillus oryzae for enhanced biosynthesis of phytase through chemical mutagenesis
Ikram Ul Haq, Muhammad Bilal Saeed, Ali Nawaz, Zannara Mustafa and Fatima Akram
Abstract
The present study deal with strain improvement through random chemical mutagenesis of phytase producing Aspergillus oryzae UJIIB-29. Aspergillus oryzae wild strain UJIIB-29 was exposed to three different chemical mutagens i.e. sodium azide, nitrous acid and ethyl methane sulfonate (EMS). Thirty isolates obtained after treating with chemical mutagens showing the large zone of phytic acid hydrolysis were picked and subjected to secondary screening for phytase production using submerged fermentation on phytase screening media. The mutant NA-4 obtained after treating wild strain with nitrous acid exhibited maximum activity of phytase (44± 0.01 U/ml/min). It was approximately 1.9 folds higher than enzyme activity (23.1±0.01 U/ml/min) of parent strain. To further increase the phytase activity, fermentation conditions like fermentation media, time of incubation, incubation temperature, pH of the medium, carbon source and its different concentrations, nitrogen source and its different concentrations and size of inoculum were optimized. The maximum phytase units (58.98± 0.01 U/ml/min) were achieved in glucose phosphate broth (M) having 1% starch, 0.4% ammonium sulphate as a carbon and nitrogen sources, respectively, at 30 C, having pH 4.5 after 7days of incubation period. As a result of optimization, 1.3 times increased in phytase activity (58.98± 0.01 U/ml/min) was achieved. Nitrous acid proved to be a potent mutagen for strain improvement. Furthermore, optimized fermentation parameter can help in scaling up the phytsae production using Aspergillus oryzae NA-4
To Cite this article:
Haq, I.U., M.B. Saeed, A. Nawaz, Z. Mustafa and F. Akram. 2022. Strain improvement of Aspergillus oryzae for enhanced biosynthesis of phytase through chemical mutagenesis. Pak. J. Bot., 54(6): DOI: http://dx.doi.org/10.30848/PJB2022-6(17)
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