Studies On The Gut Microbiota Of Macrotermes Barneyi

Termite is a kind of insect living in subtropical or tropical regions. Termites can digest cellulose in their feeding plant material, playing very important roles in carbon cycle of the world. For the past few years, the high efficient lignocellulose hydrolysis ability of termites draw great attention of many researchers.Termites are generally divided to lower termites and higher termites, according to the existence of intestinal protozoa. Lower termites have a simple intestinal structure, and their hindgut possess large number of symbiotic flagellates protozoa assisting lower termites decomposing lignocellulose. Higher termites have more elaborate gut structure than that of lower termites. The complex intestinal structure feature could help high termites keep food much more time in the guts and make lignocellulose digested completely. In special, higher termites lack protozoa in their hindguts.There are many studies in the lower termites and relatively clearer knowledge about cellulolytic mechanism of the lower termites has been obtained:a dual digestion mechanism—termite secreted endogenous cellulases and symbiotic microbe secreted exogenous cellulases contribute cooperatively to the high lignocellulose degradation ability. However, how higher termites degrade cellulose is still not clearly reported.Large number of microbes exist in termite gut. Research on gut symbiotic microorganism can help us understand the lignocelluloses digestion mechanism, but The termite gut symbiotic microbes is few reported. In order to understand roles of the higher termites gut symbiotic microbes in lignocellulose degradation, the fungus-growing termite Macrotermes barneyi was studied in this study.Primarily, the bacterial diversity in the midgut and hindgut of the higher termite M. barneyi, is investigated using high-throughput16S rDNA sequencing. The results revealed a significant difference in the abundance of microbiota between the midgut and hindgut. The dominant phyla in the hindgut were Bacteroidetes and Firmicutes, while the most abundant phylum (～96%) in the midgut was Proteobacteria. Hindgut bacteria diversity is also higher than that of midgut according to bacterial diversity statistic estimators, ACE, Chao, Shannon and Simpso Sencondly, as a successful group of wood-degrading organisms, M. barneyi hindgut harbors large quantity of microbes. We cultivate hindgut microorganism use restricted nutrition media that include filter paper as sole carbon source. Seven bacteria and three fungi were detected using denatured gradient gel electrophoresis (DGGE). Seven bacteria are from Bacillus, Microbacterium, Proteobacterium, and Achromobacter, respectively. Three fungi are from Sordariomycetidae and Galactomyces. Lignocellulose digestion ability was also verified by native-page method.Finally, we screened hindgut symbiotic microbes and obtained xylan-digestion bacteria Mb1-6, which belongs to Paenibacillus. The bacteria can secreted more than one xylanase revealed by zymogram analysis.In brief, we focus on M. barneyi and analyze the bacteria diversity and diversity difference between midgut and hindgut. Filter paper digestion microbiome was obtained. Cellulose digestion enzymes were detected by zymogram analysis. Also, xylan hydrolysis bacteria Mb1-6from Paenibacillus was obtained. The above research indicates that the hindgut bacteria is much more diverse than that of midgut; Also, hindgut microbe have cellulose-digestion ability, assisting termites lignocelluloses hydrolysis. Meanwhile, bacterial-origin xylanase was discovered, further suggesting the important roles in termite lignocelluloses digestion.