| Odontotermes formosanus is a kind of typical fungus-growing insects.It can build a fungus comb in the nest to cultivate Termitomyces and take it as food.Xylaria is an important competitor during the cultivation of Termitomyces.Once the termite colonies began to decline,Xylaria will be in large quantities without the control of termites,infecting the entire fungus comb very soon and the nest to be destroyed.To clarify the inhibitory effect of symbiotic microorganisms on Xylaria during the cultivation of Termitomyces,this study determined the species and abundance of microorganisms in nymphs,young workers,old workers,soldiers,queen and fungus comb of Odontotermes formosanus,and the differences in the structure of the main bacteria and actinobacteria were identified.The symbiotic actinomycetes which can inhibit the growth of Xylaria without affecting the growth of Termitomyces are isolated from the old workers.In order to further excavate new antibacterial substances,the symbiotic actinomycetes are revealed to Termitomyces and Xylaris.The mechanism of asymmetric bacteriostatic function provides a reference for comprehensive understanding of the reciprocal relationship between symbiotic microorganisms and termites.The main results are as follows: 1.Symbiotic microbial diversity of Odontotermes formosanusA total of 11137496 Tags sequences were detected in all samples of this experiment,which were clustered into 117117 OTUs,and then 16 gates were identified,namely Bacteroidetes,Firmicutes,Proteobacteria,Spirochaetae and Actinobacteria etc,among which Bacteroidetes,Firmicutes and Proteobacteria have a higher species abundance.However,the proportions of different grades of worms and bacillary dysentery are different.The Bacteroidetes is the dominant flora of young workers and old workers,and the Firmicutes is dominant flora of nymphs and soldiers.Firmicutes and Proteobacteria are the dominant flora of the queen,Bacteroidetes and proteobacteria are the dominant flora of the fungus comb.2.Symbiotic actinobacteria diversity of Odontotermes formosanusThe relative abundance of actinomycetes in all samples was 3.70% on average,and 5 classes,17 orders,40 families,and 84 genera were detected by clustering and annotation.The content of Coriobacteriia in the sodliers,young workers,old workers and nymphs are higher,and the relative abundance of the species is 79.950% of the Actinobacteria.While The content of Actinobacteria in the queens and the fungus comb are higher,and the relative abundance is 17.548%.According to the Shannon index,the species of actinobacteria in the fungus comb of Odontotermes formosanus are the most uniform and abundant,and the old workers are second.3.Isolation and identification of microorganisms from the nest of Odontotermes formosanusIn this experiment,the selection medium was used to separate and purify the small white spheres and Xylaria on the fungus comb of Odontotermes formosanus,and sequence homology analysis showed that they are Termitomyces sp.and Xylaria angulosa.In this experiment,101 strains were selected according to the morphology of actinomycetes by using 10 different culture media,and most of the actinomycetes isolated were(Streptomycetales,Streptomycetaceae)Streptomyces and Kitasatospora,(Pseudonocardiales,Pseudonocardiaceae)Amycolatopsis and Pseudonocardia,(Corynebacteriales,Nocardiaceae)Nocardia,(Propinibacteriales,Nocardioidaceae)Nocardioides etc.4.The antibacterial activity of cultivable actinomycetesBy measuring the effect of the isolated actinomycetes and their fermentation broth on Termitomyces and Xylaria,27 strains of actinomycetes with strong inhibitory effect on Xylaria were screened out and 19 strains of actinomycetes with weak inhibitory effect on Xylaria were screened out.Among them,25 strains of actinomycetes inhibited the growth of Termitomyces with weak effect.In addition,the strains which broth have strong inhibition on Xylaria,while have weak inhibition on Termitomyces are Streptomyces No.8 and No.46,and Amycolatopsis.No.2,No.3 and No.45. |
