Wood-feeding Termite Species Research Articles

Are wood-feeding and fungus-growing termites so different? Comparison of the organization and properties of Microcerotermes pakistanicus and Odontotermes obesus soil constructions in the Western Ghats, India

This study aimed to compare the properties of the constructions made by Microcerotermes pakistanicus, a wood-feeding termite species building carton nests, to those made by the fungus-growing termite Odontotermes obesus in a secondary forest in the Western Ghats region of Kerala. X-ray computed tomography (X-ray CT) showed that the pinnacle of O. obesus termitaria was very thick and compact with a central cavity and numerous unconnected galleries in its inner part. Conversely, the construction of M. pakistanicus appeared as a very porous media made of abundant and connected galleries following a radial trajectory, and the galleries were separated from the others by a thin wall. Despite significant differences in terms of soil chemical properties, Odontotermes obesus termitaria and sheetings had similar properties to those of the surrounding topsoil. Conversely, M. pakistanicus nest had unique chemical properties distinct from those of O. obesus or the surrounding soil. Moreover, although M. pakistanicus builds carton nests from its faeces, minerals were also measured within its termitaria. In conclusion, this study shows the very different properties of O. obesus and M. pakistanicus constructs. It also suggests the need for soil ecologists to consider carton-nests as a third group of soil-nest type, in addition to those built by soil or litter feeders and fungus-growers which edify termitaria from soil and different amount of organic matter. Further studies are also needed to determine their functional impacts on soil and nutrient dynamics.

Termites Are Associated with External Species-Specific Bacterial Communities.

All termites have established a wide range of associations with symbiotic microbes in their guts. Some termite species are also associated with microbes that grow in their nests, but the prevalence of these associations remains largely unknown. Here, we studied the bacterial communities associated with the termites and galleries of three wood-feeding termite species by using 16S rRNA gene amplicon sequencing. We found that the compositions of bacterial communities among termite bodies, termite galleries, and control wood fragments devoid of termite activities differ in a species-specific manner. Termite galleries were enriched in bacterial operational taxonomic units (OTUs) belonging to Rhizobiales and Actinobacteria, which were often shared by several termite species. The abundance of several bacterial OTUs, such as Bacillus, Clostridium, Corynebacterium, and Staphylococcus, was reduced in termite galleries. Our results demonstrate that both termite guts and termite galleries harbor unique bacterial communities.IMPORTANCE As is the case for all ecosystem engineers, termites impact their habitat by their activities, potentially affecting bacterial communities. Here, we studied three wood-feeding termite species and found that they influence the composition of the bacterial communities in their surrounding environment. Termite activities have positive effects on Rhizobiales and Actinobacteria abundance and negative effects on the abundance of several ubiquitous genera, such as Bacillus, Clostridium, Corynebacterium, and Staphylococcus Our results demonstrate that termite galleries harbor unique bacterial communities.

Termites host specific fungal communities that differ from those in their ambient environments

Termites are important plant biomass decomposers. Their digestive activity typically relies on prokaryotes and protozoa present in their guts. In some cases, such as in fungus-growing termites, digestion also relies on ectosymbiosis with specific fungal taxa. To date, the mycobiome of termites has yet to be investigated in detail. We evaluated the specificity of whole-termite associated fungal communities in three wood-feeding termite species. We showed that the whole-termite fungal community spectra are stable over diverse environments, regardless of the host species, and differ markedly from the wood in which they nest. The core mycobiome is similar to that found in other ecologically related insects and consists of a narrow spectrum of common filamentous fungi and yeasts, known for their stress tolerance and their ability to decompose plant biomass. The observed patterns suggest that a number of fungal strains may have a symbiotic relationship with termites, and our results set the stage for future investigations into the interactions between fungi, termites, and their other gut microbiota. • Termite body associated mycobiome is systematically studied for the first time. • Whole termite bodies were used as a proxy for the intestinal mycobiota study. • Body associated fungal communities differ from the ambient environment. • Body associated communities are stable over variable habitats and termite species. • This is a first sign that termites have a symbiosis with intestinal fungi.

Changes in the Phenolic Fraction of Protobind 1000 and Bacterial Microbiota in the Gut of a Higher Termite, Nasutitermes Ephratae

Termites are examples of natural biomass utilization systems that have evolved to overcome the recalcitrance of lignin to degradation. To investigate the application of this to the conversion of technical lignins produced by biorefineries, a higher wood-feeding termite species, Nasutitermes ephratae, was fed with a commercial grass soda lignin (Protobind 1000, PB1000). We investigated the fate of PB1000 in termite guts and the changes in gut microbiota that occurred using Pyrolysis - Gas Chromatography / Mass Spectrometry (Py-GC/MS) and high-throughput sequencing of the 16S rRNA genes. The worker caste termites fed with PB1000 had only half the survival rate of the controls and increased the PB1000 syringyl/guaiacyl ratio from 1.74 to 2.26. The changes in the syringyl/guaiacyl ratio were consistent with the degradation of the free phenolic monomers in PB1000 inside the termite gut, and they were associated with the increase in the relative abundance of Firmicutes and Bacteroidetes. This work showed the ability of the digestive tract of a wood-feeding higher termite species, N. ephratae, to metabolize the free-volatile phenolic monomers in PB1000. Overall, our results identified bacterial candidates for the development of a bacterial inoculum in pretreatment processes for the utilization of technical lignin in biorefineries.

Gut-specific actinobacterial community structure and diversity associated with the wood-feeding termite species, Nasutitermes corniger (Motschulsky) described by nested PCR-DGGE analysis

This comprehensive survey studied the actinobacterial community structure and putative representative members associated with the gut of the wood-feeding termite, Nasutitermes corniger (Motschulsky), using nested PCR-DGGE and 16S rDNA sequences analyses. The closest relatives of the actinobacteria inhabiting the gut of Nasutitermes corniger were in five families, regardless of the geographical origin of the termite colony: Propionibacteriaceae, Streptomycetaceae, Cellulomonodaceae, Corynebacteriaceae and Rubrobacteraceae. Feeding termites on beech wood did not result in substantial changes in the actinobacterial community structure as revealed by DGGE banding patterns. Most of the 16S rDNA sequences obtained after excision and sequencing of DGGE bands clustered with those previously retrieved in termite guts. These results confirm the presence of gut-specific actinobacteria. Except for the 16S rDNA sequences affiliated to Streptomycetaceae and Cellulomonodaceae, no sequence had more than 97% similarity with the closest isolated strains, indicating the presence of microorganisms that have not yet been cultivated. These results suggest that members of the Actinomycetales order account for the largest proportion of the Actinobacteria phylum inhabiting the gut of the termite N. corniger.

Methane emission from wood-feeding termites in Amazonia

The contribution of termites to the global methane budget has been controversely discussed in the last decade. We measured methane emissions from nests of wood-feeding termite species ( Nasutitermes spp.) of primary and secondary forests of Amazonia. The methane emission rates from single termite nests varied in a broad range between 0.01 and 9.4 mg CH 4 hour −1 nest −1 (average = 2.0 ± 2.4 mg CH 4 hour −1 nest −1), as termite colonies vary considerably in size (biomass). Consequently, data given as methane emission per nest are unsuitable for interspecific comparison. In seek for an appropriate unit the methane flux was related to the biomass of the termites dwelling in the nest. On this basis, the variation between the methane emissions of the nests was far lower (0.4 – 4.9 μg hour −1 g termites −1). Biomass-related methane emission rates averaged 3.0 ± 1.3 μg hour −1 g termites −1, which means that Amazonian termites release significantly (at p = 0.01%) more methane than species from other regions. By extrapolating these emission rates to the estimated global biomass of termites we calculated a total emission of 26 Tg CH 4 year −1, which represents about 5 % of the annual methane flux from all sources to the world atmosphere. Termites are unlikely to contribute essentially to the global budget of the “greenhouse gas” methane.