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Published July 2011 | public
Journal Article

RNA-seq reveals cooperative metabolic interactions between two termite-gut spirochete species in co-culture

Abstract

The hindguts of wood-feeding termites typically contain hundreds of microbial species. Together with their insect host, these gut microbes degrade lignocellulose into usable catabolites. Although past research revealed many facets of the stepwise flow of metabolites in this scheme, not much is known about the breadth of interactions occurring between termite-gut microbes. Most of these microbes are thought to depend on, and to have co-speciated with, their host and each other for millions of years. In this study, we explored the interactions of two spirochetes previously isolated from the very same termite species. As hydrogen (H_2) is the central free intermediate in termite-gut lignocellulose digestion, we focused on interactions between two closely related termite-gut spirochetes possessing complementary H_2 physiologies: one produces H_2, while the other consumes it. In vitro, these two Treponema species markedly enhanced each other's growth. RNA sequencing resolved the transcriptomes of these two closely related organisms, revealing that co-cultivation causes comprehensive changes in global gene expression. The expression of well over a 100 genes in each species was changed >twofold, with over a dozen changed >10-fold. Several changes implicating synergistic cross-feeding of known metabolites were validated in vitro. Additionally, certain activities beneficial to the host were preferentially expressed during consortial growth. However, the majority of changes in gene expression are not yet understandable, but indicate a broad, comprehensive and mutualistic interaction between these closely related, co-resident gut symbionts. The results suggest that staggeringly intricate networks of metabolic and gene interactions drive lignocellulose degradation and co-evolution of termite gut microbiota.

Additional Information

© 2011 International Society for Microbial Ecology. Received 26 August 2010; revised 16 November 2010; accepted 22 December 2010; published online 17 February 2011. We thank our laboratory colleagues and participants in Caltech's GEC facility for their insights and advice. This research was supported by the DOE (DE-FG02-07ER64484) and the NSF (EF-0523267), Genome sequences for the two bacterial species are deposited with Genbank under the following accession numbers: (CP001843) and (CP001841).

Additional details

Created:
August 22, 2023
Modified:
October 24, 2023