Function Of Oxalate-degrading Bacteria In The Maintenance Of Termite-Termitomyces Symbiotic System And The Culture Of Xylaria Nigripes From Abandoned Nest

Termites are a kind of typical herbivorous insects.After transporting the plant material to the nest,it finally constitutes a rich oxalate pool.This provides abundant raw materials for the metabolic activities of oxalate-degrading bacteria.In addition,it constitutes an ecological relationship between the interaction of termites,Termitomyces and oxalate-degrading bacteria,which has important research value.However,when the termites moved,the abandoned nest no longer grow Termitornyces but turn to the Xylaria,and the original ecological relationship has undergone major changes.This phenomenon has not been reasonably explained so far.The scientific reason is worth further exploration.In conclusion,the metabolic activity of oxalate-degrading bacteria can mineralize oxalate into carbonate.The study of biotransformation process(OCP)is of great value not only for understanding the maintenance of termite-Termitomyces symbiotic system,but also for clarifying this particular ecology.The mechanism of carbon migration and transformation in the environment is also of scientific significance.In this study,genomic DNA was extracted from nine termite nest samples,and the microbial diversity of different samples parts was analyzed.The frc gene of oxalotrophic bacteria(coding formyl Co A transferase)was sequenced,and the diversity of oxalate-degrading bacteria at different sites was analyzed.Physical and chemical indicators of nest and nest wall soil were determined.The results showed that the community structure of termite nest was significantly different from that of termite nest wall and surface soil,and the oxalate degrading bacteria richness in the Termite Nest<Termite Nest Wall<Surface Soil.Quantitative analysis of oxalotrophic bacteria using the functional gene frc qPCR showed that the bacterial copy number of Termite Nest Wall(5.70×10⁸±1.92×10⁸ copies/g dry soil)<Termite Nest(9.87×10⁸±2.03×10⁸copies/g dry soil).This indicated that the presence and activity of termites significantly affected the abundance of oxalotrophic bacteria in the termite microenvironment.A bacterial strain TA1 with oxalate degradation function was obtained from termite nest soil by single carbon source screening method.The bacterial secondary minerals after degradation were identified by X-ray diffraction(XRD),scanning electron microscopy(SEM-EDS).It was verified that the strain could transform Ca O_X into Ca CO₃(OCP).The physical and chemical indicators showed that there were significant differences in oxalate content,carbonate content and pH value about samples.That is,the content of oxalate is significantly higher than that of the nest wall.The pH value is significantly lower than that of the nest wall,and the content of calcium oxalate is lower than that of the nest wall.The correlation between oxalotrophic bacteria and various detection indicators was evaluated.There was a negative correlation between oxalate/carbonate content and soil pH.These results indicate that termites are closely related to the abundance of in situ oxalotrophic bacteria.Accordingly,the authors suggest that the effect of termites on the abundance of special bacterial groups can improve the physical and chemical properties of the termite nest microenvironment,making it more conducive to maintaining the termite-Termitomyces symbiotic system.As two dominant fungi in termite environment,Termitornyces albuminosus(Berk)Heim and Xylaria nigripes,they have a complex ecological relationship with termites.In order to explore the survival mechanism of termite nest niche,a trinity of oxalotrophic bacteria,T.albuminosus and X.nigripes was formed.In this paper,we explored a new strain isolation method,optimized and selected suitable culture conditions,and successfully cultured the mycelia and fruiting bodies of X.nigripes,so that the biological characteristics of the two fungi could be studied.The results showed that the abandoned nests of termites could be quickly covered with the mycelia of X.nigripes in laboratory environment.Both T.albuminosus and X.nigripes cultured in liquid medium had the phenomenon of disintegration of filter paper,which could be used to determine their cellulose degradation performance.Oxalic acid can be produced by T.albuminosus itself,so the oxalate material brought in by termites will not affect its growth.Oxalic acid can be used as degradation substrate of oxalate-degrading bacteria and provide food source for the enrichment of a large number of functional bacteria.We simulated the microenvironment of the termite nest and explored the biological characteristics of the two fungi using the metabolites of oxalate-degrading bacteria.The results showed that the mycelia of X.nigripes did not germinate under acidic conditions(pH=4.0)and even stopped growing completely.Under the same conditions,T.albuminosus could still grow normally,but the mycelium germination time was slow.For the environmental factor of CO₂,high CO₂ concentration(15%CO₂)did not inhibit the mycelial germination of X.nigripes,but inhibited the formation of fungal rhizomorph.However,CO₂ concentration did not inhibit the germination of Termitomyces mycelium.The results of this study preliminarily analyzed the ecological relationship among T.albuminosus,X.nigripes and oxalotrophic bacteria in termite nests,and laid a good foundation for further development and utilization of X.nigripes.The results of this study preliminarily analyzed the ecological relationship between T.albuminosus,X.nigripes and oxalotrophic bacteria in the nest,and clarified the ecology of oxalate-degrading bacteria in symbiotic system.and laid a good foundation for the further development and utilization of X.nigripes.