Parallel metatranscriptome analyses of host and symbiont gene expression in the gut of the termite Reticulitermes flavipesReport as inadecuate




Parallel metatranscriptome analyses of host and symbiont gene expression in the gut of the termite Reticulitermes flavipes - Download this document for free, or read online. Document in PDF available to download.

Biotechnology for Biofuels

, 2:25

First Online: 15 October 2009Received: 31 May 2009Accepted: 15 October 2009

Abstract

BackgroundTermite lignocellulose digestion is achieved through a collaboration of host plus prokaryotic and eukaryotic symbionts. In the present work, we took a combined host and symbiont metatranscriptomic approach for investigating the digestive contributions of host and symbiont in the lower termite Reticulitermes flavipes. Our approach consisted of parallel high-throughput sequencing from i a host gut cDNA library and ii a hindgut symbiont cDNA library. Subsequently, we undertook functional analyses of newly identified phenoloxidases with potential importance as pretreatment enzymes in industrial lignocellulose processing.

ResultsOver 10,000 expressed sequence tags ESTs were sequenced from the 2 libraries that aligned into 6,555 putative transcripts, including 171 putative lignocellulase genes. Sequence analyses provided insights in two areas. First, a non-overlapping complement of host and symbiont prokaryotic plus protist glycohydrolase gene families known to participate in cellulose, hemicellulose, alpha carbohydrate, and chitin degradation were identified. Of these, cellulases are contributed by host plus symbiont genomes, whereas hemicellulases are contributed exclusively by symbiont genomes. Second, a diverse complement of previously unknown genes that encode proteins with homology to lignase, antioxidant, and detoxification enzymes were identified exclusively from the host library laccase, catalase, peroxidase, superoxide dismutase, carboxylesterase, cytochrome P450. Subsequently, functional analyses of phenoloxidase activity provided results that were strongly consistent with patterns of laccase gene expression. In particular, phenoloxidase activity and laccase gene expression are mostly restricted to symbiont-free foregut plus salivary gland tissues, and phenoloxidase activity is inducible by lignin feeding.

ConclusionTo our knowledge, this is the first time that a dual host-symbiont transcriptome sequencing effort has been conducted in a single termite species. This sequence database represents an important new genomic resource for use in further studies of collaborative host-symbiont termite digestion, as well as development of coevolved host and symbiont-derived biocatalysts for use in industrial biomass-to-bioethanol applications. Additionally, this study demonstrates that: i phenoloxidase activities are prominent in the R. flavipes gut and are not symbiont derived, ii expands the known number of host and symbiont glycosyl hydrolase families in Reticulitermes, and iii supports previous models of lignin degradation and host-symbiont collaboration in cellulose-hemicellulose digestion in the termite gut. All sequences in this paper are available publicly with the accession numbers FL634956-FL640828 Termite Gut library and FL641015-FL645753 Symbiont library.

Electronic supplementary materialThe online version of this article doi:10.1186-1754-6834-2-25 contains supplementary material, which is available to authorized users.

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Author: Aurélien Tartar - Marsha M Wheeler - Xuguo Zhou - Monique R Coy - Drion G Boucias - Michael E Scharf

Source: https://link.springer.com/



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