Study On Secondary Metabolites And Biological Activities Of Fungus Aspergillus Wentii

With the rapid development of society and the rapid increase in population,chemically synthesized pesticides are widely used because of their high pesticidal efficiency and low price.A series of problems were followed,such as environmental pollution,ecological balance damage and threats to food safety.The new pesticides derived from the natural environment and mainly based on natural products have the advantages of good insecticidal effect,easy degradation,good selectivity and rare pollution to the environment,it has gradually become the focus of people's research and development of new green pesticides.The starting point of this research is to select a higher active strain CCH-2(Aspergillus wentii)derived from the crude sea cucumber of Qingdao sea area for separation,purification and activity screening,and establish the necessary theoretical basis for the development of environmentally friendly pesticides.Four different strains were selected to optimize the fermentation of the four strains,and the strains were screened from three aspects: productivity,richness of metabolites and antibacterial activity: Firstly,from the perspective of productivity,the amount of fermentation product in RICE medium is the largest,the effect is the best,and the amount of product in PDB medium is also large,which is conducive to further research;It can be seen from the richness of metabolites displayed in TLC plates that the product of strain CCH-2 in RICE medium is the most abundant,with abundant fluorescent spots and color spots,and other strains are not as obvious as CCH-2;In terms of antibacterial activity,strain CCH-2 had the largest inhibition zone against BS at 2w(22mm in diameter),close to the positive control(24mm diameter of inhibition zone),and the activity was strong.The strain H-01 was in 4w to SA.The inhibitory effect is also obvious(the inhibition zone diameter is 19 mm).In summary,the strain CCH-2 with strong activity and strong growth ability was selected as the experimental strain for further research.According to the optimized culture results,the CCH-2 strain was subjected to scale fermentation using RICE medium,and the metabolite was subjected to VLC gradient elution.The crude extracts of different polar components are screened for bacteriostatic activity,The results showed that the Fr7-Fr15 component had strong activity,and the component Fr13 had the highest activity against XC,and the inhibition zone diameter reached 25 mm.The components were separated and purified by various column separation methods such as a silica gel column,a gel column,and a reverse phase column to obtain nearly 20 monomer compounds.The antibacterial activity of the monomeric compounds was screened,and it was found that the inhibition of WT-7 on the indicator bacteria was the most obvious.The diameter of inhibition zone of SA,BS and EC has reached more than 15mm;WT-10 has certain selectivity,and the diameter of inhibition zone of BT is 15mm;WT-11 has a certain broad-spectrum antibacterial activity and the inhibition is more obvious,where in the inhibition zone diameter of the BS is 15 mm.In summary,this paper systematically provides a theoretical basis for the development and utilization of marine microbial resources through the study of strain CCH-2 isolated from marine algae,and also provides a new research idea for the development of environmentally friendly new pesticides.