| Termites represent astonishingly efficient lignocellulosic bioconversion system in nature, which has been considered as an important model to study lignocellulose-to-energy conversion and potential uses in the production of biofuels. Fungus-growing termites in subfamily Macrotermitinae specifically cultivate basidiomycetes fungi (Termitomyces spp.) in their nest, which are successful in the almost complete decomposition of lignocellulose in cooperation with exosymbiotic fungi. In this thesis, the lignocellulolytic potentials of fungus-comb in fungus-growing termites(Odontotermes formosanus Shiraki) is taken as an object to study and elucidate its’ factors of microbial stabilization. The main research results are as follows:(1) Determination of physiochemical microenvironment of fungus-comb of O. formosanus.By employing series of techniques including ICP-MS and ICS, physiochemical profiles of fungus-comb of O,formosanus including moisture content, pH, metal ion and VFA (volatile fatty acid) concentrations were analyzed. The result shows that the upper and lower fungus-comb exist significant difference on moisture content. For pH values, the middle fungus-comb shows significant difference with the upper and lower fungus-combs. Additionally, the VFA in the fungus-comb was measured by ICS-3000, and results show that five main VFAs (Formate, Acetate, Butyrate, Succinate, Lactate) are existed in fungus-comb, as well as spatial distribution patterns. Furthermore, by ICP-MS, the concentration of14metal ions in the fungus-comb were measured, and9out of14metal ions (Na、Al、Fe、K、Cd、Mo、Ni、Ba、Pb) show significantly different in spatial distribution among individual layer of fungus-comb.(2) Cultivation, identification and observation of exosymbiotic fungi Termitomyces spp. in O. formosanus.Improved Martin medium and MYA medium are used to cultivate fungi from the fungus-comb of O. formosanus. The results show that Improved Martin medium is better than MYA medium for fungi growth. Based on solid cultivation, we further study fungal growth on these two liquid mediums under different pH, and the results show that the fungal mass increased higher in Improved Martin medium than in MYA medium. Besides, the growth conditions of fungi under different pH present as normal distribution. By using PCR, the sequence of exosymbiotic fungi of O. formosanus is determined. After Blast comparison, the isolated fungi was proved to be one of Termitomyces spp.. Moreover, in order to testify the effects of fungus-comb materials on fungal growth, an appropriate amount of fungus-comb materials powder was added in Improved Martin medium. The growth situation are different among four different treatments through direct observation, especially in normal Improved Martin medium with fungus-comb materials, where the fungi grows better than other3treatments. Compared with other treatments, we observed that the fungal colony is white, slight oval, and much denser mycelium.(3) The enrichment, isolation, cultivation and function identification of small-scale microbial community from fungus-comb of O.formosanus.Through filter paper medium, the lignocellulolytic potentials of microbial community from fungus-comb of O. formosanus are screened. After cultivating about30days, only filter paper was dissolved, which can’t prove whether the bacteria with functions of lignocellulose degradation. Based on the result above, carbohydrate profiles of the media with bacteria cultivated30days was tested by GPC. The result shows that there are mannitol, glucose, fructose, lactose, and sucrose in the culture media. Compared to blank control, the mannitol increased significantly, glucose and lactose also showed increasing trend, while the sucrose and fructose were significantly decreased. These show that in the process of cultivating, the microbial community from fungus-comb can metabolize and consume the components in upper fungus comb. |
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