Screening Of Lactobacillus Plantarum Producing Fibrinolytic Enzyme And Study On The Characterizations Of Fibrinolytic Enzyme

Lactobacillus plantarum is a versatile lactic acid bacterium that is widely.Fibrinolytic enzyme can dissolve fibrin in the thrombus,and it is the main active ingredient of drugs for treating thrombotic diseases.It is of great significance to screen out fibrinolytic enzyme-producing Lactobacillus plantarum from traditional fermented foods and study its biological characteristics and plasmin properties.In this research,a strain of high-producing fibrinolytic enzyme-producing lactic acid bacteria was isolated from traditional fermented food such as tempeh,the strain was identified and its probiotic characteristics were analyzed.The basic enzymatic characteristics of the fibrinolytic enzyme produced were mainly analyzed.The results are as follows:（1）Seven strains producing fibrinolytic enzyme were isolated from traditional fermented food such as tempeh by skimmed milk plate preliminary screening and fibrin plate re-screening method.The strain with the highest fibrinolytic activity was selected and named HQ-3.The enzyme activity of the fermentation supernatant was 497.6 U/m L.According to morphology and other identification,the strain HQ-3 was identified as Lactobacillus plantarum.The fibrinolytic enzyme produced was named LPF.（2）Some probiotic characteristics of the strain HQ-3 showed that the strain HQ-3 is sensitive to 13 common antibiotics by varying degrees such as imipenem,and only resistant to penicillin;the strain have a certain bacteriostatic ability to E.coli,Staphylococcus aureus,and Salmonella.,and the diameters of their bacteriostatic circles are 17.5 mm,18.5 mm,and 20.2mm,respectively;HQ-3 has a better tolerance to the simulated gastrointestinal tract,the survival rate of cultured artificial simulated gastric juice was 98.75%with different p H gradient acids,and the survival rate after treatment with artificial intestinal fluid was 72.92%,and the number of viable bacteria was 10⁷CFU/m L;The au-aggregation rate of the strain reached 73.56%after 25 hours of aggregation,and the co-aggregation rates with E.coli and Staphylococcus aureus were 68.92%,57.89%,respectively;When the strain was cultured with xylene,chloroform and ethyl acetate,the aggregation rates were 47.52、45.91 and27.55%,respectively;the adhesion rate of strain HQ-3 to yeast cells was 57.3%,and the adhesion gene slp2588 was detected by PCR.（3）The supernatant of strain HQ-3 was used to extract crude protein to obtain concentrated crude enzyme solution of fibrinolytic enzyme LPF by salting out,dialysis,concentration and ultrafiltration.The results of native page showed that the crude enzyme solution contained fibrinolytic active components for one.This crude enzyme solution is used to study the basic enzymatic properties of the sample,the results showed that fibrinolytic enzyme LPF uses an indirect method to degrade fibrin,that is,to degrade fibrin by activating fibrinolytic enzymeogen;and the optimal reaction temperature of the enzyme is 45℃,the optimal p H is 3.0,Na⁺and Fe²⁺can activate the fibrinolytic enzyme LPF enzyme activity,and K⁺,Ba²⁺,and Cu²⁺have a slight inhibitory effect on the fibrinolytic enzyme enzyme;the inhibitor gastric enzyme inhibitor A can partially inhibit the activity of fibrinolytic enzyme LPF.In this study,a new strain of Lactobacillus plantarum HQ-3 that produced plasmin was isolated.The probiotic characteristics of this strain were studied;plasmin LPF was preliminary purified and analyzed basic enzymatic properties;it is expected to provide a reference for the application of potential probiotic strains producing fibrinolytic enzymes in food and other industries.