Comparative Transcriptome Profiling Of Different Intestinal Part And Purification The Xylanase Of The Midgut Of Macrotermes Barneyi

Termites(Insecta,Isoptera)are widely distributed in tropical and subtropical regions.Termites have strong ability to degrade the lignocelluloses and play a vital role on transforming biomass materials in tropical and subtropical ecosystems.Understanding the lignocellulose degradation mechanism of termites may provide a novel solution for the biomass-to-ethanol industry and alleviating the global energy and environmental crisis.In lower termite,endogenous(termite origin)and exogenous cellulases(symbiont origin)cooperatively contribute to the high ability of lignocellulose degradation.In wood-feeding higher termites,due to the absence of flagellated protistan symbionts in the hindgut,the bacteria existing in the hindgut help to accomplish the degradation of celluloses and hemicelluloses.As for fungus-growing termites,they also rely on their symbiotic fungus to decompose plant substrate.The lignocelluloses degradation in the fungus comb is managed in a highly structured way,the older workers collect crude forage material and bring it back to the nest,and younger workers ingest it together with asexual Termitomyces spores(conidia)provided by fungal nodules from established "fungus-garden combs",then they produce primary feces that are deposited as new layers of the comb.This new substrate quickly develops dense hyphal networks and produces the next cohorts of nodules,whereas older termites ultimately consume the old comb.In order to understand the lignocelluloses degradation mechanism more deeply in the fungus-growing termite,Macrotermes barneyi was used in this study.About 18 kDa xylanase was purified from the midgut of M.barneyi where the highest xylanase activity was presented.Further the N-terminal amino acid sequences was determined,but the corresponding cDNAs have not been obtained.Subsequently,the transcriptome among each part of the intestinal gut was analyzed and compared,and we focused on the difference expression of lignocellulase in the transcriptome.As a result,136 unigenes of glycoside hydrolase were found,and they were identified belonging to 29 glycoside hydrolase families.Through comparatively analysis,many unigenes expressed differently in different gut part,indicating their different effects in the gut.And no relevant information about the xylanase(GHF10,GHF11)were found in the transcriptome.Owing to lacking the details about the genome of higher fungus-growing termites,transcriptome have not been completely analyzed.In conclusion,a xylanase about 18 kDa from midgut of M.barneyi had been purified,since the corresponding cDNAs had not been cloned yet,the origin of the xylanase gene was unknown.In addition,many unigenes involving in lignocelluloses degradation were obtained.It was found that many unigenes had different expression,indicating the different roles of each gut part in the process of degradation.This study provides more details to understand the mechanism of lignocelluloses degradation by M.barneyi.