Endophytic Fungi And Rhizosphere Microorganisms Of Casuarina Equisetifolia And Their Antibacterial Activities

Endophytic fungi and rhizosphere microorganisms of Casuarina equisetifolia were isolated by tissue block separation method and heat shock dilution method in this thesis,respectively.Endophytic fungi and rhizosphere microorganisms were identified by colony observation and molecular biology methods,and their organisms diversity were also analyzed.The secondary metabolites of both endophytic fungi and rhizosphere microorganisms of Casuarina equisetifolia were extracted and prepared by liquid fermentation.The antibacterial activity of these secondary metabolites were tested by the TLC-MTT-Bioautography for five tested bacteria such as R.solanacearum.The main results are as follows:1.Twenty endophytic fungi were isolated from Casuarina equisetifolia,which named Cef-1～Cef-20,belonged to fifteen different genera after identification.Botryosphaeria sp.(Cef-1,Cef-12,Cef-16)was the highest separation frequency strain,which was the dominant genus covered 20%.The Margalef richness index(D’),Simpson dominance index(D),Shannon-Wiener diversity index(H’)and Pielou of endophytic fungi isolated from Casuarina equisetifolia were 4.67,0.92,2.59 and0.96,respectively.The antibacterial activity results showed that Cef-17(Eutypella sp.),Cef-18(Penicillium sp.)and Cef-20(Penicillium sp.)displayed the strongest inhibitory activity against five tested bacteria.The inhibition zone diameter of Cef-20 was more than 10 mm.The R_f value was distributed between 0.00-0.95,which mean a wide range of polar distribution compound.2.A total of twenty-five fungi were isolated from the rhizosphere soil,named Cesf-1～Cesf-25,respectively.They belonged to thirteen different genera after identification.Penicillium sp.(Cesf-3,Cesf-5,Cesf-7,Cesf-13,Cesf-16,Cesf-18)was the dominant genus,and the value was 24%.The values of Margalef richness index(D’),Simpson dominance index(D),Shannon-Wiener diversity index(H’)and Pielou evenness index(J)were 2.08,0.88,2.34 and 0.91,respectively.Cesf-9(Aspergillus sp.),Cesf-11(Paecilomyces sp.),Cesf-13(Penicillium sp.)and Cesf-16(Penicillium sp)showed the best antibacterial activity against five tested bacteria.The inhibition zone diameter of Cesf-16 was greater than 10 mm,and the R_f value was 0.00-0.70.3.A total of eighteen actinomycetes were isolated from the rhizosphere soil named Ceaf-1～Ceaf-18,which belonged to seven different genera.Among these genera,the separation frequency of Streptomyces sp.(Ceaf-1,Ceaf-4,Ceaf-6,Ceaf-9,Ceaf-12,Ceaf-15,Ceaf-16)was 38.9%,which was the dominant genus.The Margalef richness index(D’),Simpson dominance index(D),Shannon-Wiener diversity index(H’)and Pielou evenness index were were 2.08,0.77,1.67 and 0.86,respectively.Ceaf-3(Leclercia sp.),Ceaf-13(Enterobacter sp.)and Ceaf-14(Bacillus sp.)showed strong inhibitory activity of bacteria against five tested bacteria and the inhibition zone diameter was 5-10 mm.This research clarified the inhibitory activity of endophytic fungi and ehizosphere microorganisms of Casuarina equisetifolia against five tested bacteria.Endophytic fungi Cef-20,rhizosphere fungi Cesf-16 and rhizosphere actinomycetes Ceaf-3 showed the strongest inhibitory activity against R.solanacearum,which could be further studied as a potential strain to control R.solanacearum and utilization of bio-sourced pesticides.