Study Of The Diversity And Antimicrobial Activity Of Culturable Actinomycetes From Odontotermes Formosanus

The pretty tough insect is the largest population in nature.They are symbiotic and coevolved with a wide variety of microorganisms.Due to the complexity and diversity of living environment and food species,the microorganisms symbiotic with insects show the characteristic of species diversity.It endows more opportunities for discovering potential new species of microorganisms and new natural products from them.In this paper,84 strains of actinomycetes,including 2 potential new species,were isolated and purified by using dilution plate method from Odontotermes formosanus.And one strain was selected according to the antifungal activity effect and the yield of metabolites.Macroporous resin,silica gel,gel chromatography column and recrystallization were used as methods to isolate and purify the active metabolites.The structures of the active substances were identified by NMR and ESI-MS.In this paper,one novel compound was isolated and identified,and the antimicrobial activity was tested.Relevant studies are summarized as follows:1?A total of 84 strains of actinomycetes were isolated and purified by dilution-plate method.The identification results showed that the 84 strains of actinomycetes were divided into 4 genera and 21 different species,79 of which were from Streptomyces,2 from Kribbella,1 from Fibrobacteria and 2 from Amycolatopsis through 16S-PCR and the analysis of phylogenetic trees.The similarities between the two actinomycetes BYF53 and BYF119 from Amycolatopsis and the strain Amycolatopsis echigonensis LC2(T)were less than 98.65%,They were potential new species of actinomycetes.2?Using the confrontation method to inhibit the activity of plant pathogenic fungi in all isolated actinomycetes,the results showed that 22 strains of actinomycetes exhibited fungistatic activity,of which 4 strains showed inhibitory activity against all plant pathogenic fungi,and the diameter of fungistasis circle was between 3-20 mm.Among them,BYF106 and BYF74 could inhibit the growth of Alternaria solani with an obvious fungistasis circle,which is over 20 mm;The ethyl acetate crude of BYF106's activity against fungi was carried out by the growth rate method further,it showed inhibitory activity against 9 plant pathogenic fungi,of which the highest activity were against Botrytis cinerea and Colletotrichum graminicola with the inhibition rate more than 80%when the final concentration of the ethyl acetate crude as 100 ?g/mL.The antibacterial activity of the extract was tested by filter paper diffusion method.The results showed that the extract had no significant inhibitory activity against Escherichia coli.But the antimicrobial circle diameters of Staphylococcus aureus and Micrococcus Tetragenus were 15.9 mm and 16.7 mm,which were slightly weaker than that of gentamicin sulfate(25.6 mm and 34.9 mm)at the concentration of 30 ?g/filter paper.3?Two monomer compounds BYF106-1 and BYF106-2 were isolated from the crude ethyl acetate extract of strain BYF106 by various chromatographic methods,they were identified as grincamycin N(BYF 106-1),fridamycin D(BYF 106-2)by mass spectrometry and nuclear magnetic resonance spectroseopy.The activity test showed that compound BYF 106-1 had no significant inhibitory activity against E.coli,while it exhibited inhibitory activity to the positive bacteria well at the concentration of 30 ?g/filter paper.The diameter of the inhibitory circle against S.aureus was 13.8 mm,which was similar to that of the positive control gentamycin sulfate with 19.9 mm,it also showed good inhibitory activity against M.tetragenus with the diameter was 17.6 mm,which was weaker than that of the positive control gentamycin sulfate witih 30.8 mm.Compound BYF 106-2 also showed no significant activity against E.coli.The diameters of the inhibitory zones for the other two bacteria were 9.9 mm and 10.7 mm,which were slightly weaker than gentamicin sulfate.