Enhanced Production of Streptokinase by UV- and Ethidium Bromide-Treated Streptococus equisimilis Mutant
Enhanced Production of Streptokinase by UV- and Ethidium Bromide-Treated Streptococus equisimilis Mutant
Muhammad Naeem1, Bushra Sadia1,2,*, Faisal Saeed Awan1and Muhammad Anjum Zia3
ABSTRACT
Streptokinase (SK) is a thrombolytic agent having broad applications in treatment of various diseases like ischemia, Budd-Chiari syndrome, myocardial infarction, brain stroke and myocardial infarction. Strain improvement is an important approach for its hyper production. In this connection, wild bacterial strain Streptococcus equisimilis was mutagenized using ethidium bromide and UV radiation. The colonies (15 each) showing > 1% survival rate at 150 min of UV exposure and 12 % survival at 0.5 mg/ml of ethidium bromide for 120 min were selected. Casein hydrolytic assay identified EB3, EB4, EB6, EB7, EB9, EB11, EB13, UV2, UV4, UV6, UV7, UV9, UV11, UV12 and UV 15 mutants producing halo zones. Percentage blood clot lysis led to screening of mutants UV 2, UV 6, UV 7, UV 9, UV 11, UV 12, UV 15 and EB 3, EB 4, EB 11, EB 13 with hyperactivity as compared to wild bacterial strain. Out of the total 15 isolates of EtBr-treated strains, EB4 gave the maximum enzyme activity (7.3 ± 0.005 U ml-1) with a zone diameter of 6 mm. While UV6 was found to be the best UV-induced mutant with an enzyme activity of 20.333 ± 0.006A U ml-1 and 16 mm of zone diameter. The current results indicated 400 % and 146% enhanced SK activity in mutants UV6 and EB4, respectively, compared to wild type. UV6 also exhibited the highest enzyme activity (14.667± 6.5) after precipitation with ammunium sulphate, at concentrations as low as 30 μl. Optimized conditions for maximum yield of mutant SK included CSL 6%, 24 h. of fermentation, pH 7.5, 37oC, KH2PO4 0.04%, K2HPO4, NaHCO3 0.15% and 0.015% CH3COONa. The results indicated that UV is the most effective mutagen for hyper-production of SK. Mutant strain UV6 has the potential for enhanced SK production with commercial applications.
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April 2018
Vol. 50, Iss. 2, Pages 401-797
