Evaluating the role of Actinobacteria in the gut of wood-feeding termites (Reticulitermes spp.)

IRG/WP 17-10880

Evaluating the role of Actinobacteria in the gut of wood-feeding termites (Reticulitermes spp.)

Nitrogen has been shown to be a limiting nutrient across a range of xylophagous insects. These insects often rely on symbiotic microorganisms in the gut for nitrogen acquisition, via fixation of atmospheric nitrogen or break down of other available nitrogenous substances. In phylogenetically lower, wood-feeding termites, the role of nitrogen fixing bacteria has been well studied. However, there is also evidence that uric acid can be metabolized into ammonia and serve as an additional nitrogen source. In this study, 36 Actinobacterial isolates (Streptomyces spp.) from the guts of Reticulitermes flavipes (Kollar) and Reticulitermes tibialis Banks, were screened for uric acid breakdown using culture-based methods. Results showed 92% of isolates are capable of degrading uric acid, with 35% classified as having “very strong” uricase activity in vitro. Enzyme assays of four representative Actinobacterial isolates confirmed that uric acid was broken down and ammonia was produced. Soil materials manipulated by termites also showed increased uricase activity compared to soil alone. However, this increase was not accompanied by an increase in overall abundance of Actinobacteria. It is still possible, however, that only those Actinobacteria with uricase activity increase while others remain the same or decrease, which would not change overall abundance values. Results from this study support the hypothesis that Actinobacteria associated with the gut of wood-feeding termites have the potential to contribute to nitrogen acquisition via uricolysis. Future work will be aimed at better understanding this complex relationship between wood-feeding subterranean termites and gut-associated Actinobacteria.

Keywords: subterranean termites, gut bacteria, nitrogen, uric acid, pH

Conference: 17-06-04/08 Ghent, Belgium

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