Strain improvement, optimization and purification studies for enhanced production of streptokinase from Streptococcus uberis TNA-M1

Abstract

Screening of isolates for their potency to produce streptokinase was an important criterion of this research. The current study emphasizes the strain improvement, optimization and purification studies for enhanced production of streptokinase from Streptococcus uberis TNA-M1 isolated from bovine milk. The study was carried out on samples collected from milk sample. Primary screening and characterization is used as an excellent source for the isolation of β-hemolytic organisms. Strain improvement was done by both physical & chemical mutagenesis. The enzyme activity was checked by clot lysis assay and confirmed by fibrin plate method. The partially purified and crude enzyme were analysed by high-performance liquid chromatography. Molecular weight & enzyme purity was checked by SDS–PAGE, further confirmed by fibrin zymography. Out of the 3 isolated strains, only one isolate expressed β-haemolysis with streptokinase (SK) activity. Based on the results of radial caseinolytic assay and blood clot dissolving assay, isolate TNA-M1 demonstrated the highest streptokinase activity. Based on morphological, biochemical and molecular characterization, it was identified as Streptococcus uberis and the strain was named as Streptococcus uberis TNA-M1. The results indicated that ultra-violet (UV) and ethyl methane sulfonate (EMS) were effective mutagenic agents for strain improvement of Streptococcus uberis TNA-M1 and enhanced SK productivity. HPLC analysis was performed in order to confirm the presence of streptokinase with the similar retention time (0.875 min) with its standard (0.854) min. SDS-PAGE of the enzyme showed protein band of approximately 47 kDa and confirmed by fibrin zymography. It exhibited fibrinolytic activity, which was more potent than other fibrinolytic enzymes. Glucose and peptone were recorded to be the optimum carbon and nitrogen sources respectively. Thus this study presents its novelty by highlighting the potential of Streptococcus uberis TNA-M1 as a significant source for the production of fibrinolytic enzymes.