12901
10.30848/PJB2024-5(28)
<p>
Enhanced production of alkaline protease enzyme by mutated Aspergillus oryzae developed by random mutagenesis</p>
Saif-Ur-Rehman, Asad Ali, Anam Saqib, Rubab Ramzan, Haidar Ali and Muhammad Hamid Rashid
<p>
Thermostability is an important attribute and a prerequisite for the enzymes used in industrial processes. <em>Aspergillus oyzae</em> has the potential to produce proteases for industrial applications. In this study, <em>A. oryzae</em> mutants were used to identify hyper-producers of thermostable proteases. Initially, 22 mutants were selected on the basis of their growth performance, cultured on 1% skimmed milk media plates and <em>Clearing Indexes</em> (<em>CI</em>). Five mutants with higher ‘<em>CI</em>’ were selected for submerged fermentation employing 1% casein as substrate and following growth conditions were used: pH 6.5, temperature 30°C and shaking at 150 rpm for 84 hr. Irreversible thermostability was determined at 65°C using pseudo-first order plots. Mutant strain M-120(3) showed highest production and thermostability of protease compared to control and other mutants with half-life (t<em>½</em>) of 125 min. Effect of temperature and substrate concentration on growth kinetics of Mutant M-120(3) were determined showing optimum temperature of 32°C with a specific growth rate (<em>µ</em>) of 0.037h<sup>-1</sup> and specific rate of product formation (<em>q<sub>p</sub></em>) of 0.31 (U g<sup>-1</sup>h<sup>-1</sup>). Kinetics and thermodynamic parameters confirmed that mutant strain M-120(3) required less activation energy (<em>E<sub>a</sub></em>) to produce protease enzyme (<em>E<sub>ap</sub></em> = 65.22 kJ mol<sup>-1</sup>) and cell mass (<em>E<sub>ax</sub></em> = 29.074 kJ mol<sup>-1</sup>) than control strain. It had low maximum specific rate of cell mass formation (<em>µ<sub>max</sub></em>) 0.043 kJ mol<sup>-1</sup> and higher maximum specific rate of product formation (<em>q<sub>p</sub></em>) 1.07 kJ mol<sup>-1</sup>. These parameters confirmed that Mutant M-120(3) had great potential for commercial scale production of thermostable proteases for industrial application</p>
Published
2024
56
5
1799
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