Wood is a difficult material for organisms to digest. The rotting and decomposition of fallen trees can take years to complete. Wood is mostly cellulose reinforced with lignin. The lignin is refractory to digestion by many organisms and is a barrier to the utilization of cellulose as a food source. The lignin must be processed in order to access the cellulose. Utilizing wood as a food source in termites is not an individual species project but a collaboration of many species.
Termites have special structures in the gut to house symbiotic microorganisms including flagellate species that only exist in the guts of termites. The termites chew wood, grind it into small pieces, coat it with digestive fluid and create a suitable environment for the flagellates to survive. The flagellates contribute digestive enzymes and nutrients such as vitamins to the termites. Flagellates in the genus, Trichonympha, do not act alone. The flagellates themselves have bacterial symbionts that live both externally and internally. Advances in DNA technology have facilitated identification of bacterial symbionts and opened a path to their study.
Termites can host a diversity of flagellate species. The flagellate, Trichonympha agilis has deep invaginations in its plasma membrane that are colonized by bacterial symbionts in the Genus, Desulfovibrio. Desulfovibrio are clearly external, but their close association can facilitate exchange of substances between the bacteria and the flagellate. Bacterial endosymbionts, Candidatus Ancillula trichonymphae, are widely distributed among species in the genus Trichonympha. The endosymbionts are present in the cytoplasm in the anterior portion of the flagellate. The endosymbiont complexes found in termites are complicated and will require years of study to comprehend their functions and relationships.
Strasser & Colleagues. ‘Candidatus Ancillula trichonymphae’, a novel lineage of endosymbiotic Actinobacteria in termite gut flagellates of the genus Trichonympha. Environmental Microbiology (2012) 14(12), 3259–3270.