Effects Of Different Plant Materials On Feeding And Culturing Symbiotic Organisms Of Odontotermes Formosanus

As a completely social insect,termites are the most efficient lignocellulose-degrading organisms in nature world through division of labor and cooperation among individuals from different castes.Fungus-growing termites can specially cultivate symbiotic fungi,Termitomyces,and become the main decomposer of plant residues in tropical areas through termites-fungus-bacteria symbiotic system.This dissertation investigated the symbiotic system of Odontotermes formosanus.On the basis of comparing the feeding preference of O.formosanus to different plant materials and effects of different fungus combs components on the growth of Termitomyces to explore the degradation ability of lignocellulose by Termitomyces and the effects of plant materials on the construction of fungus combs.The following results obtained:(1)Ten plant materials(Quercus palustris leaves piled up for 1 month,2 month,3 month,and sawdust of Ulmus pumila,Pinus massoniana,Populus tomentosa,Quercus palustris,Morus alba,Robinia pseudoacacia,Paulownia elongate)were used as O.formosanus baits to compare the feeding situation.The results indicated that there was no significant difference in the time of discovering each plant material by termites,but the bait consumption and bait consumption rate for U.pumila sawdust was significantly higher than that of others.The preference for feeding each plant material from high to low were U.pumila sawdust,Q.palustris leaves piled up for 3 months,Q.palustris leaves piled up for 2 months,Q.palustris leaves piled up for 1 month,M.alba sawdust,R.pseudoacacia sawdust and Q.palustris sawdust.While P.elongata sawdust,P.massoniana sawdust and P.tomentosa sawdust were almost not fed.Based on the single plant material tests,the U.pumila sawdust and Q.palustris leaves were mixed with different mass ratios as baits.The results indicated that there was no significant difference in feeding preference among different baits,and the preference for feeding U.pumila sawdust was slightly higher than that of mixed baits.(2)Different components of O.formosanus fungus combs were extracted by deionized water and n-pentane,and added into the modified Martin medium as additives to compare the effects of different components on the growth of Termitomyces.The results indicated that the growth area of Termitomyces did not increased after adding different components of fungus combs to the modified Martin medium,and even some of them inhibited.However,the biomass of Termitomyces increased significantly in some treatments.In addition,the growth area and biomass of Termitomyces on different media were measured after using the same amount of dried power of O.formsanus fugus combs to replace different components of modified Martin medium respectively.The results indicated that there was no significant difference in the growth area of Termitomyces among different media,but the biomass of Termitomyces was significantly higher than control group when using fungus combs to replace glucose(P<0.01),tryptone(P<0.05)or MgS04·7H20(P<0.05).(3)The plant materials both without pretreated and pretreated by Gloeophyllum trabeum were treated by O.formosanus fungus combs,solid culture of Termitomyces and liquid culture of Termitomyces,respectively,for which to investigate the ability of Termitomyces to degrade lignocellulose.The result indicated that Termitomyces has a certain degradation effect on lignocellulose,and the lignocellulose degradation rate of pretreated plant materials by O.formosanus fungus combs,solid culture of Termitomyces and liquid culture of Termitomyces was higher than the non-pretreated plant materials.The degradation ability of both cellulose and hemicellulose were fungus combs>solid culture of Termitomyces>liquid culture of Termitomyces,and the degradation ability of lignin was solid culture of Termitomyces>fungus combs>liquid culture of Temitomyces.(4)Three kinds of agricultural wastes(rice straw,maize straw,cow dung)and three kinds of forestry wastes(U.pumila sawdust,Cunninghamia lanceolate sawdust,M.alba sawdust)with different pretreatemt were used as food for O.formosanus.Then,the pH,water content,crude protein content,hemicellulose content,cellulose content,lignin content and ash content of the new-built fungus combs were compared.The results indicated that the feeding preference of termites on different kinds of agricultural and forestry wastes was different,and there was no new-built fungus combs after feeding on some of the wastes.Overall,the pH,hemicellulose content and ash content of new-built fungus combs feeding on agricultural wastes were higher than those of feeding on forestry wastes,but the lignin content of new-built fungus combs feeding on agricultural wastes was lower than that of feeding on forestry wastes.(5)High-throughput sequencing was used to compare the diversity of bacteria in different layer of new-built fungus combs of O.formosanus after feeding on three kinds of plant materials(Q.palustris leaves,Q.palustris branches,and mixed plant materials).The results indicated that the bacterial richness of new-built fungus combs after feeding on different foods was highest in the middle layer,while the bacterial diversity varied with food type,but the bacterial diversity in the upper and middle layers were higher than the lower layer.During the maturation of fungus combs,the key phylum of bacteria gradually changed from Bacteroidetes to Proteobacteria,while Spirochaetes and Synergistetes disappeared.In addition,Spirochaetes does not exist in the intestinal tract of O.formosanus,but the bacteria of the genus Treponema with nitrogen fixation and ligocellulose degradation ability was detected in the new-built fungus combs.At the same time,Burkholderia spp.and Ochrobactrum spp.with the ability of detoxification,Firmicutes and Dysgonomonas spp.of Bacteroidetes with the ability of lignocellulose degradation,and Lactococcus spp.that can produce acid were also found.In conclusion,this dissertation screened out the plant materials preferred by O.formosanus,found the effects of fungus combs on the biomass growth of Termitomyces,verified the ability of Termitomyces to degrade lignocellulose,and compared the effects of different plant materials on fungus combs construction.This study not only provides a new raw material for the bait research of O.formosanus,but also provides a new method for accelerating the mycelium growth of Termitomyces on the culture media.It also provides a theoretical basis for the application of Termitomyces in biomass energy development and artificial cultivation of Termitomyces as edible fungi.