The Study On Determination, Extraction And Flocculation Conditions Of The Flocculating Activity Lactobacillus Paracasei

ObjectiveThe part and composition of active substances of Lactobacillus paracaseiwere identified,then insuring the best method in different ways.Studying onoptimum culture conditions and restraining the combing between starch andflocculating with inhibitors to obtain purified flocculating,which lays a theoreticalfoundation for studying on the spatial space and binding sites and developing anew microbial flocculant.MethodsTesting the active flocculation,heat stability and enzyme stability to confirmthe part and composition of active substances,comparing the content of activesubstances and electrophoretogram in different extracting methods.Then basedon single-factor experiment and Box-Behnken central compositeexperiment,three response factors including pH, temperature and the contentof protein solution were select as response factors and flocculation rate wasused as response value.Based on single-factor experiment and orthogonalexperiment to insure the best inhibitor and inhibition conditions，then theisolated flocculation were procedured by eletrophoresis. ResultsThe flocculation activity substances were identified as protein namedstarch-protein on the cell wall through studying on flocculation activity ofLactobacillus paracasei.Then with different extraction methods,ultrasonicmethod is the best in obtaining the content of protein and getting highflocculability.The optimum conditions of flocculation is pH6.0, temperature35℃and the content of proteinsolution1.5mL. Based on single-factorexperiment and orthogonal experiment to insure the best inhibitor is cholate andinhibition conditions were temperature30℃, pH7.0and the density of cholate0.1g/mL.The separation protein and starch combined starch-protein wereprocedured by electrophoresis,molecular weight of starch-protein is between30kDa and55kDa.ConclusionsThe flocculation activity substances were protide, which still has flocculatingactivity when isolated from the cells. Inhibitors could separate the protein fromthe starch and we could get the molecular weight of starch-protein withelectrophoresis.