A marine‑derived fibrinolytic protease from Bacillus paramycoides AL6: Partial purification, preliminary characterization and in vivo antithrombotic efficacy

Thrombosis is a pathological condition characterized by blood clot formation that obstructs blood flow and contributes substantially to morbidity and mortality worldwide.Limitations of conventional thrombolytic therapies have prompted the development of enzyme-based alternatives, particularly microbial fibrinolytic enzymes.The present study aimed to identify the AL6 bacterial isolate, partially purify and preliminarily characterize its fibrinolytic protease and evaluate its antithrombotic efficacy in vivo.Molecular identification using the 16S rRNA gene revealed that the AL6 isolate shared 98.27% similarity with Bacillus paramycoides.The enzyme preparation was subjected to anion-exchange chromatography, yielding a partially purified fibrinolytic enzyme preparation with protein bands in the 30-50 kDa range on SDS-PAGE.In vitro fibrinolytic activity, assessed by clot lysis, increased with increasing enzyme volume, with clot lysis values of 47.02±3.00,57.00±3.67 and 76.30±3.17%at enzyme volumes of 100, 200 and 300 µl, respectively.However, they remained lower than those of streptokinase (81.25-92.31%).In vivo antithrombotic efficacy was evaluated using a κ-carrageenan-induced mouse tail thrombus model, in which the partially purified enzyme markedly reduced thrombus length compared with the negative control and exhibited a dose-dependent effect.The highest thrombus reduction (52.54%) was achieved at 0.88 mg/kg body weight and was not markedly different from the positive control.Preliminary safety assessment showed that bleeding time remained within normal limits, suggesting no apparent alteration in hemostasis under the tested conditions.Overall, the partially purified fibrinolytic protease preparation from B. paramycoides AL6 demonstrated promising in vitro fibrinolytic activity and in vivo antithrombotic efficacy.However, further purification, biochemical characterization and comprehensive safety evaluation are required to determine its potential for future therapeutic development.