Screening Of Chitosan Degradation Strains And Application Of Its Products

Chitosan oligosaccharides?COS?is a oligosaccharides with biological activity derive from shrimp and crab shells.COS is produced by hydrolysis of chitosan.COS has been used in agriculture,and it can promote seed germination,and improve plant immunity and crop resistance.In this work,the degradation stains of chitosan is screened and its hydrolysis products is applied in plant growth for research the effect of COS on plant germination,growth and resistance.Three strains,Aspergullus niveusus,Aspergillus fumigatusus and Mucor circinelloidesus,were isolated from seawater,sediment and crab shell.Then the culture conditions and degradation conditions were optimized and the degradation products were obtained under the optimal conditions.The optimal medium was chitosan,1%peptone,1%beef extract,0.2%MgSO₄,0.3%NaCl,pH4.5.The optimal condition of enzyme production and chitosan hydrolysis was pH3.5,3%chitosan,25^oC with Aspergullus niveusus;pH4.0,2%chitosan,35^oC with Aspergillus fumigatusus and Mucor circinelloidesus.The hydrolysis products were analyzed by Gel Permeation Chromatography and ion chromatography.The average molecular weight of hydrolysis products of Aspergullus niveusus were 2432,its degree of was relatively small and broad range.The average molecular weight of hydrolysis products of Aspergillus fumigatusus were 7100,its degree of was relatively big and broad range.The average molecular weight of hydrolysis products of Aspergillus fumigatusus were 2891,its degree of was relatively small and narrow range.COS could significantly improved the germination ability of seeds of barley corn and pakchoi using soaking seed by COS.COS could increased the DPPH,ABTS,protein content,polyphenol content and peroxidase activity in seeding of barley,corn and pakchoi using foliar spray by COS.The results showed that COS could promote the germination and growth of plant,and improved the plant resistant.So,COS as a plant growth regulator and protective agent has the important meaning in agriculture.