title: Metatranscriptomic profiles of Eastern subterranean termites, Reticulitermes flavipes (Kollar) fed on second generation feedstocks.
abstract: BACKGROUND
  Second generation lignocellulosic feedstocks are being considered as an alternative to first generation biofuels that are derived from grain starches and sugars. However, the current pre-treatment methods for second generation biofuel production are inefficient and expensive due to the recalcitrant nature of lignocellulose. In this study, we used the lower termite Reticulitermes flavipes (Kollar), as a model to identify potential pretreatment genes/enzymes specifically adapted for use against agricultural feedstocks.
  
  
  RESULTS
  Metatranscriptomic profiling was performed on worker termite guts after feeding on corn stover (CS), soybean residue (SR), or 98% pure cellulose (paper) to identify (i) microbial community, (ii) pathway level and (iii) gene-level responses. Microbial community profiles after CS and SR feeding were different from the paper feeding profile, and protist symbiont abundance decreased significantly in termites feeding on SR and CS relative to paper. Functional profiles after CS feeding were similar to paper and SR; whereas paper and SR showed different profiles. Amino acid and carbohydrate metabolism pathways were downregulated in termites feeding on SR relative to paper and CS. Gene expression analyses showed more significant down regulation of genes after SR feeding relative to paper and CS. Stereotypical lignocellulase genes/enzymes were not differentially expressed, but rather were among the most abundant/constitutively-expressed genes.
  
  
  CONCLUSIONS
  These results suggest that the effect of CS and SR feeding on termite gut lignocellulase composition is minimal and thus, the most abundantly expressed enzymes appear to encode the best candidate catalysts for use in saccharification of these and related second-generation feedstocks. Further, based on these findings we hypothesize that the most abundantly expressed lignocellulases, rather than those that are differentially expressed have the best potential as pretreatment enzymes for CS and SR feedstocks.
authors.affiliation: Department of Entomology, Purdue University, West Lafayette, 47907-2089, Indiana. prajarap@purdue.edu.
authors.forename: Swapna Priya
authors.initials: SP
authors.lastname: Rajarapu
authors.affiliation: Bioinformatics Core, Purdue University, West Lafayette, 47907-2089, Indiana. jtshreve@purdue.edu.
authors.forename: Jacob T
authors.initials: JT
authors.lastname: Shreve
authors.affiliation: Bioinformatics Core, Purdue University, West Lafayette, 47907-2089, Indiana. bhide@purdue.edu.
authors.forename: Ketaki P
authors.initials: KP
authors.lastname: Bhide
authors.affiliation: Bioinformatics Core, Purdue University, West Lafayette, 47907-2089, Indiana. jyothit@purdue.edu.
authors.forename: Jyothi
authors.initials: J
authors.lastname: Thimmapuram
authors.affiliation: Department of Entomology, Purdue University, West Lafayette, 47907-2089, Indiana. mscharf@purdue.edu.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Scharf
mesh_terms: D000818:Animals; D002480:Cellulase / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D020049:Isoptera / Q000201:enzymology / Q000235:genetics*; D008031:Lignin / Q000737:chemistry / Q000378:metabolism*; D013025:Glycine max / Q000737:chemistry / Q000378:metabolism; D059467:Transcriptome / Q000235:genetics*; D003313:Zea mays / Q000737:chemistry / Q000378:metabolism
chemical_list: C036909:lignocellulose; D008031:Lignin; D002480:Cellulase