Abstract: Screening and isolating the fibrinolytic strains of Sipunculus nudus in the North of Guangxi by a combination of skim milk plate and fibrin plate assay,the specificity and fibrinolytic mechanism of the strain were analyzed. As a result,5 strains isolated and screened from Sipunculus nudus showed ability of fibrin degradation. The crude enzyme fermented from the strain GXUSP-1 presented the maximal fibrinolytic activity as 303.2 U/mL（equivalent to urinary kinase activity unit）. GXUSP-1 was identified as Bacillus cereus,and belonged to marine symbiotic bacteria. Meanwhile,thrombolytic effect in vitro of the crude enzyme fermented from GXUSP-1 was significant,which dissolved thrombus both directly and indirectly. GXUSP-1 demonstrates promising potential industrial application.

Key words: Sipunculus nudus, fibrinolytic enzyme, Bacillus cereus, identification