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Title: Single-cell genomics of Treponema and other microbiota isolated from xylophagous termites
Author: Starns, David Edward
ISNI:       0000 0004 6422 4636
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2016
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The nutritional symbiosis between the wood feeding termite and its microbiota is an important model of biomass conversion. Recalcitrant wood is broken down to its basic components and is transformed into energy for the sustenance of the host termite. The microbial community is responsible for cellulose degradation, reductive acetogenesis and nitrogen fixation activities within the gut, and is composed of diverse bacteria, archaea and protists. A prominent taxon within the community is Treponema, a genus of helical motile bacteria. In the higher termite Nasutitermes takasagoensis treponemes are the dominant taxa with the potential of reductive acetogenesis, nitrogen fixation and cellulose degradation, they are joined by members of TG3 and Fibrobacteres and work synergistically in the utilisation of recalcitrant wood components. The genomes of these organisms were analysed using single cell genomics to assign putative functions to these uncultured bacteria and metatranscriptomics to uncover the contributions within the whole community. In the lower termite Hodotermopsis sjoestedti, treponemes are dominant taxa within the cellulolytic protist Eucomonympha. Here the treponeme has evolved an endosymbiotic lifestyle to sustain the host by reductive acetogenesis from H2 and CO2 to supply acetate and nitrogen fixation, and has lost its helical and motile characteristics. This elucidation was made possible again by use of single cell genomics and biochemical analyses. Treponemes from the lower termite Reticulitermes speratus were also sequenced and used in conjunction with other treponeme sequences from diverse environments to classify important genes associated with the environments they were isolated from. Virulence factors from human periodontal strains were the most important at distinguishing the environment they were associated with, whereas termite associated treponemes were categorised by central metabolic genes.
Supervisor: Darby, A. C. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral