Soil-feeding Termite Research Articles

Biodegradation of aniline blue dye by salt-tolerant Bacillus thuringiensis DHC4 isolated from soil-feeding termite guts

The existence of aniline blue in aquatic environments poses a large threat to aquatic organisms. Microbial degradation of aniline blue has been frequently used in remediation because of its effectiveness, low cost, and environmental friendliness. However, the mechanisms by which the dye can be biodegraded are not well understood. In this study, Bacillus thuringiensis DHC4 was isolated from the gut of a soil-feeding termite, and its ability to degrade aniline blue was investigated. The results showed that DHC4 was highly resistant to both aniline blue and salt, with the decolorization rate reaching 78% and 67% after 96 h of incubation at initial dye concentrations of 1 g/L and 7% salinity, respectively. Aniline blue degradation products were identified based on UV–vis, FTIR, and GC–MS analyses, and genome analysis confirmed that DHC4 contained many potential dye-degrading genes. Transcriptome analysis revealed significant up-regulation of methyltransferase, nitroreductase, arylamine N-acetyltransferase and oxidoreductase genes on exposure to aniline blue, indicating their active role in its biodegradation. A new degradation pathway of aniline blue by DHC4 is proposed, based on analysis of metabolites and differentially expressed genes. This mechanism involves cleavage of aniline blue by oxidoreductases into mono- and diphenyl ring molecules, followed by further methylation and alkylation through methyltransferases. The phytotoxicity results showed that aniline blue was degraded by DHC4 into less toxic metabolites. These results provide new insights into the mechanism of biodegradation of aniline blue by microorganisms.

A holobiont approach towards polysaccharide degradation by the highly compartmentalised gut system of the soil-feeding higher termite Labiotermes labralis

BackgroundTermites are among the most successful insects on Earth and can feed on a broad range of organic matter at various stages of decomposition. The termite gut system is often referred to as a micro-reactor and is a complex structure consisting of several components. It includes the host, its gut microbiome and fungal gardens, in the case of fungi-growing higher termites. The digestive tract of soil-feeding higher termites is characterised by radial and axial gradients of physicochemical parameters (e.g. pH, O2 and H2 partial pressure), and also differs in the density and structure of residing microbial communities. Although soil-feeding termites account for 60% of the known termite species, their biomass degradation strategies are far less known compared to their wood-feeding counterparts.ResultsIn this work, we applied an integrative multi-omics approach for the first time at the holobiont level to study the highly compartmentalised gut system of the soil-feeding higher termite Labiotermes labralis. We relied on 16S rRNA gene community profiling, metagenomics and (meta)transcriptomics to uncover the distribution of functional roles, in particular those related to carbohydrate hydrolysis, across different gut compartments and among the members of the bacterial community and the host itself. We showed that the Labiotermes gut was dominated by members of the Firmicutes phylum, whose abundance gradually decreased towards the posterior segments of the hindgut, in favour of Bacteroidetes, Proteobacteria and Verrucomicrobia. Contrary to expectations, we observed that L. labralis gut microbes expressed a high diversity of carbohydrate active enzymes involved in cellulose and hemicelluloses degradation, making the soil-feeding termite gut a unique reservoir of lignocellulolytic enzymes with considerable biotechnological potential. We also evidenced that the host cellulases have different phylogenetic origins and structures, which is possibly translated into their different specificities towards cellulose. From an ecological perspective, we could speculate that the capacity to feed on distinct polymorphs of cellulose retained in soil might have enabled this termite species to widely colonise the different habitats of the Amazon basin.ConclusionsOur study provides interesting insights into the distribution of the hydrolytic potential of the highly compartmentalised higher termite gut. The large number of expressed enzymes targeting the different lignocellulose components make the Labiotermes worker gut a relevant lignocellulose-valorising model to mimic by biomass conversion industries.

Allochthonous material originating from saprolite as a marker of termite activity in Ferralsols

Ferralsols, which are estimated to cover 7.5 millions km2 worldwide, are deeply weathered red or yellow soils found in the humid tropics. They are considered as the end of a geochemical sequence of weathering and are dominated by low-activity clay and sesquioxides. Their physical properties are closely related to their strong submillimetric granular structure. We aimed to characterize the 2:1 clay minerals identified in many Ferralsols and to discuss them as a marker of soil-feeding termite activity in Ferralsols. We present results recorded with Brazilian Ferralsols developed under Cerrado native vegetation on a range of parent materials. It was found that the 2:1 minerals vary from weakly weathered muscovite to hydroxy-Al interlayered vermiculite, sometimes associated to a fine material with a chemical composition highly different from that of the groundmass of the surrounding submillimetric granular aggregates. Results show that both 2:1 minerals and the associated fine material have to be considered as allochthonous material originating from the saprolite and were brought to the Ferralsol by soil-feeding termite activity. This confirms the major role of termites in the properties of Ferralsols and raises questions about the possible consequences of land use change which usually deeply affects soil biodiversity.

New Records of Euhamitermes Holmgren From South India

Euhamitermes Holmgren is a soldier rare, soil feeding termite of the Oriental region. Two species of this genus viz., Euhamitermes lighti (Snyder) and Euhamitermes chhotanii Maiti are hereby first reported from southern Indian states of Karnataka and Kerala, respectively. Record of E. chhotanii in Kerala makes an addition of the genus and thus to the termite fauna of Kerala. These two species are redescribed and illustrated based on soldier and workers.

Soil-feeding termite diversity and abundance in a natural tropical humid forest (Tai National Park, Côte d'Ivoire)

This study aimed to contribute to the soil-feeding termite knowledge in the primary, secondary and swampy forest inside Taï National Park (Côte d’Ivoire). The objective was to assess the diversity and abundance of soil-feeding termite species in these different habitats. With a standardized method, data were collected on soil-feeding termite from habitats. The results showed a significant variation of soil-feeding termite subfamilies between the habitat types. 45 soil feeding termites species and morpho species have been recorded and identified. They belong to the Termitidae family, 3 subfamilies (Apicotermitinae, Cubitermitinae, and Termitinae), 28 genera and 428 occurrences. The highest occurrence of species (70.60%) belongs to the Apicotermitinae subfamily followed by the Termitinae (16.14%) and the Cubitermitinae (13.25%). This study has identified some new species belonging to the Apicotermitinae subfamily in the Tai National Park using the anatomy of the gut of workers. These new species will be described later.

Ebogotermes raphaeli, new genus and new species, an African soldierless termite described from the worker caste (Isoptera, Termitidae, Apicotermitinae).

Ebogotermes raphaeli gen. n. sp. n., is described from workers collected in Cameroon. This soil-feeding termite is the largest soldierless termite from central Africa and aligns with the Anoplotermes subgroup. The enteric valve armature is weakly armed and, as with most apicotermitine species, is uniquely diagnostic.

Compositional and functional characterisation of biomass-degrading microbial communities in guts of plant fibre- and soil-feeding higher termites

BackgroundTermites are among the most successful insect lineages on the globe and are responsible for providing numerous ecosystem services. They mainly feed on wood and other plant material at different stages of humification. Lignocellulose is often a principal component of such plant diet, and termites largely rely on their symbiotic microbiota and associated enzymes to decompose their food efficiently. While lower termites and their gut flagellates were given larger scientific attention in the past, the gut lignocellulolytic bacteria of higher termites remain less explored. Therefore, in this study, we investigated the structure and function of gut prokaryotic microbiomes from 11 higher termite genera representative of Syntermitinae, Apicotermitinae, Termitidae and Nasutitermitinae subfamilies, broadly grouped into plant fibre- and soil-feeding termite categories.ResultsDespite the different compositional structures of the studied termite gut microbiomes, reflecting well the diet and host lineage, we observed a surprisingly high functional congruency between gut metatranscriptomes from both feeding groups. The abundance of transcripts encoding for carbohydrate active enzymes as well as expression and diversity profiles of assigned glycoside hydrolase families were also similar between plant fibre- and soil-feeding termites. Yet, dietary imprints highlighted subtle metabolic differences specific to each feeding category. Roughly, 0.18% of de novo re-constructed gene transcripts were shared between the different termite gut microbiomes, making each termite gut a unique reservoir of genes encoding for potentially industrially applicable enzymes, e.g. relevant to biomass degradation. Taken together, we demonstrated the functional equivalence in microbial populations across different termite hosts.ConclusionsOur results provide valuable insight into the bacterial component of the termite gut system and significantly expand the inventory of termite prokaryotic genes participating in the deconstruction of plant biomass.7BKR4-UruiiWAwgYk8svodVideo

Gastrotermes spinatus gen. n. sp. n., an African soil-feeding termite described from the worker caste (Isoptera, Termitidae, Apicotermitidae)

Gastrotermes spinatus gen. n. sp. n is described from workers of a single foraging group collected in Cameroon. This soil-feeding termite aligns with the Labidotermes subgroup (Apicotermes group) because of its non-protruding and symmetrical enteric valve armature, its short P1, and its globular P3a. An asymmetrical field of robust sclerotized spines at the opening of the P3a is unique among the other Labidotermes subgroup genera.

Structure, soil properties and spatial patterning of mounds built by a soil feeding termite across a rainfall gradient in a savanna ecosystem

Although the ecosystem engineering role of termites has long been recognized, understanding the distribution and properties of their nests that affect ecosystem heterogeneity continues to be a priority. Studies have investigated soil properties like clay and organic matter (OM) composition of mounds belonging to fungus growing termites, however, little is known for southern African savanna soil feeding termites. Indeed, studies on the spatial distribution of termite mounds in savannas have been carried out with a focus mainly on the genus Macrotermes in savanna woodlands, leaving us with little information on other species that often occur on grasslands, for example soil feeding Cubitermes. Therefore, in this study we aimed to understand the effect of rainfall on Cubitermes breviceps mounds structure, soil properties and spatial point patterning at three sites. At each site two 25 m × 25 m plots were marked for spatial analysis. Mound height and basal diameter were recorded. Two soil properties (clay and OM) from mound and savanna matrix soil were investigated. A decreasing trend in mound height and diameter was observed from the more arid to the wettest site. Mound height was positively influenced by the amount of both clay and OM. However, both clay and OM had a negative relationship with numerical density of mounds, and we suggest other factors such as grass cover and the prevailing conditions such as moisture and competition at early colony establishment also influence mound density. Cubitermes breviceps mounds were generally completely spatially random across sites, except for Ripley’s L summary function that showed clustering, which we attribute to its cumulative nature. In conclusion, soil feeding C. breviceps incorporate more OM in their mounds and do not show competition between colonies probably due to them not feeding on limited food resources in the savanna such as grass and wood.

Redescription of the Soil-Feeding TermiteSinocapritermes mushae(Isoptera: Termitidae: Termitinae): The First Step of Genus Revision

The soil-feeding termite, Sinocapritermes mushae (Oshima & Maki), was described briefly in Japanese in 1919 and its type locality is Taiwan. S. mushae is the first found species of the genus, and all the other 15 congeners were described from China, and many of them were compared with S. mushae for species differentiation. However, the inconsistent interpretation of the original description of S. mushae soldier morphology occurred in Chinese literature. The winged imago of S. mushae was later described based on a single specimen collected in China, which is insufficient to represent the morphological variation and caused further confusion. To solve these problems, we re-describe and describe the soldier, winged imago, and worker enteric valve of S. mushae based on multiple colony samples collected from the type locality, Taiwan. Partial sequences of mitochondrial 16S gene confirmed that S. mushae is the only Sinocapritermes species found in Taiwan, but Taiwanese populations present high morphological variation. With the intraspecific variation of S. mushae , we demonstrated that most qualitative characters used for species differentiation among Chinese species are not valid. In addition, the morphometric data showed that the five species, Sinocapritermes sinensis Ping & Xu, Sinocapritermes songtaoensis He, Sinocapritermes tianmuensis Gao, Sinocapritermes yuannensis Ping & Xu, and Sinocapritermes xiai Gao & Lam, are not significantly different from S. mushae , and hence they are proposed as junior synonyms. This study indicates that the 15 exclusive Sinocapritermes spp. found in China need to be more thoroughly investigated, and a further revision of Sinocapritermes is necessary.

Influence of Soil Properties on Soldierless Termite Distribution.

In tropical rainforests, termites constitute an important part of the soil fauna biomass, and as for other soil arthropods, variations in soil composition create opportunities for niche partitioning. The aim of this study was twofold: first, we tested whether soil-feeding termite species differ in the foraging substrate; second, we investigated whether soil-feeding termites select their foraging sites to enhance nutrients intake. To do so, we collected termites and analysed the composition and structure of their feeding substrates. Although Anoplotermes-group members are all considered soil-feeders, our results show that some species specifically feed on abandoned termite nests and very rotten wood, and that this substrate selection is correlated with previous stable isotope analyses, suggesting that one component of niche differentiation among species is substrate selection. Our results show that the composition and structure of bare soils on which different termite species foraged do not differ, suggesting that there is no species specialization for a particular type of bare soil. Finally, the bare soil on which termites forage does not differ from random soil samples. Overall, our results suggest that few species of the Anoplotermes-group are specialized toward substrates rich in organic matter, but that the vast majority forage on soil independently of its structural and chemical composition, being ecologically equivalent for this factor.

Structure and function of subterranean gallery systems of soil-feeding termites Pericapritermes nitobei and Sinocapritermes mushae

Soil-feeding termites are a critical trophic guild comprising more than a quarter of all termite species. Most soil-feeding termites build subterranean and diffuse gallery systems that are difficult to observe. In this study, we excavated the gallery systems of two soil-feeding termite species, Pericapritermes nitobei (Shiraki) and Sinocapritermes mushae (Oshima & Maki). Termite-harboring spaces were clusters of small cells connected with tunnels, with the cells usually adjacent to underground pieces of wood, stone, thick roots, and fibrous roots. Clusters of cells in a gallery system are referred to as nodes. In total, 90 nodes of five P. nitobei colonies and 64 nodes of seven S. mushae colonies were examined. The forager proportion of P. nitobei was the highest in nodes adjacent to fibrous roots, and that of S. mushae was the highest in nodes adjacent to pieces of wood, indicating that organic matter accumulated between the fibrous roots and underneath wood acted as a carbon source for the termites to feed upon. Nursed castes of P. nitobei, including larvae and eggs, were most frequently observed under thick roots and stones, but those of S. mushae were not located under any specific object. The nesting and feeding sites of P. nitobei were separate, but those of S. mushae overlapped. We speculate that the various food sources and their distributions are likely the main selection force for the gallery structures of soil-feeding termites.

Bacillus-related Spore Formers: Attractive Agents for Plant Growth Promotion.

Bacillus-related Spore Formers: Attractive Agents for Plant Growth Promotion.

Draft Genome Sequence of the Alkaliphilic and Xylanolytic Paenibacillus sp. Strain JCM 10914, Isolated from the Gut of a Soil-Feeding Termite

Panibacillus sp. strain JCM 10914 is a xylanolytic alkaliphile isolated from the gut of a soil-feeding termite. Its draft genome sequence revealed various genes for hydrolytic enzymes and will facilitate studies on adaptation to the highly alkaline gut environment and its role in digesting soil organic matter in the gut.

Biodiversity of Termite (Insecta: Isoptera) in Tropical Peat Land Cultivated with Oil Palms

Termites are the major decomposers in tropical region but yet their occurrences in oil palm plantation especially in peat soil are generally treated as pest. Study of termite species in peat land was conducted in selected oil palm plantations in North Sarawak with 5-7 years old palms and South Sarawak with 13-15 years old palms with two sites in each area. Results of quadrate (25 x 25 x 30 cm) sampling showed termite was significantly higher in relative density with increasing depth of soil (0-10 = 21.23, 10-20 = 42.52 and 20-30 cm = 81.12%) which could be advantaged from being predated by ants (Hymenoptera: Formicidae) which were higher in density from soil surface to 10 cm soil depth with relative density of 31.84%. Modified transect sampling (50x6 m) had successfully sampled 18 species of termites from 2 families (Rhinotermitidae and Termitidae), 5 subfamilies (Rhinotermitinae, Coptotermitinae, Termitinae, Macrotermitinae and Nasutitermitinae) and 11 genera (Coptotermes, Schedorhinotermes, Termes, Macrotermes, Nasutitermes, Globitermes, Amitermes, Parrhinotermes, Pericapritermes, Havilanditermes and Prohamitermes). Both plantation sites have termite dominantly feeding on rotten wood as a result of abundant dead woods. However, Coptotermes curvignathus Holmgren was identified to feed on the living tissues of oil palm causing damage or death of the tree. Study showed higher encounter of soil-feeding termite in longer established plantation. It indicates the gradually shifting of soil condition towards a stabilized environment which favors the successful settlement of soil feeder termite species. Termite control should be more targets specific to avoid harming beneficial termites.

Are the spatio-temporal dynamics of soil-feeding termite colonies shaped by intra-specific competition?

1. Soil-feeding termites are abundant and diversified in neotropical forests, where they are among the major decomposers of the soil macrofauna. While niche specialisation along the humification gradient may reduce inter-specific competition, some species are represented by numerous colonies likely to be involved in intra-specific competition, but the subterranean nesting habits of most species of soil-feeding termites make direct observations difficult. 2. The soldierless species Anoplotermes banksi Emerson was studied, which, unlike other Anoplotermes-group species, builds arboreal nests that can be easily detected. To infer the biological processes driving the spatial distribution of this species, we conducted a 3-year survey of the dynamics of colonisation of a 1-ha plot by A. banksi. Ripley's L-function, detecting aggregation or dispersion at various spatial scales, was used to investigate the distribution pattern of A. banksi nests, as well as the distribution of new and established nests. 3. Only one-fourth of the nests recorded the first year were still alive after 3 years, highlighting a rapid turnover of the A. banksi nest population. Age classes were differentially affected by mortality, which was higher in young nests than in large, established nests. 4. Established nests were overdispersed at a short range, whereas young nests had a random or clumped distribution. Young nests tended to be overdispersed from established ones and were more abundant in areas with recently dead nests. Dead nests predominantly occurred where A. banksi nests were particularly abundant. Altogether, the present results indicate a negative interaction between neighbouring colonies suggesting intra-specific competition.

C and N concentrations in biogenic structures of a soil-feeding termite and a fungus-growing ant in the Colombian savannas

Soil ecosystem engineers such as termites and ants are able to modify physico-chemically the surrounding environment through the production of biogenic structures, thus affecting the availability of trophic and spatial resources for other organisms. The aim of this study was to assess the concentrations of C org, NH 4 + and NO 3 − in the biogenic structures produced by a soil-feeding termite ( Spinitermes sp.; Termitinae) and a fungus-grower ant species ( Atta laevigata; Myrmicinae; tribe Attini) and the surrounding soil in the Colombian “Llanos”. We tested the hypothesis that higher concentrations occur in the biogenic structures compared to control soil and that deposition of new building material at the top of the biogenic structures also increases nutrient concentrations. Sampling was conducted along a transect, at regular intervals proportional to the size of the biogenic structure. Average C org and NH 4 + concentrations were significantly higher in termite mounds than in ant nests and the control soil, whereas NO 3 − concentrations were similar. For both types of biogenic structures, the highest difference in nutrient concentrations was found between the top centre of the biogenic structure and the control soil, but significant differences were only reported for Spinitermes mounds and the control soil. No significant effect of land use on nutrient concentrations in the biogenic structures produced by either species was observed. We conclude that the activities of soil ecosystem engineers contribute to the variability of nutrient concentrations through the formation of biogenic structures.

Differences between Bacterial Communities in the Gut of a Soil-Feeding Termite (Cubitermes niokoloensis) and Its Mounds

In tropical ecosystems, termite mound soils constitute an important soil compartment covering around 10% of African soils. Previous studies have shown (S. Fall, S. Nazaret, J. L. Chotte, and A. Brauman, Microb. Ecol. 28:191-199, 2004) that the bacterial genetic structure of the mounds of soil-feeding termites (Cubitermes niokoloensis) is different from that of their surrounding soil. The aim of this study was to characterize the specificity of bacterial communities within mounds with respect to the digestive and soil origins of the mound. We have compared the bacterial community structures of a termite mound, termite gut sections, and surrounding soil using PCR-denaturing gradient gel electrophoresis (DGGE) analysis and cloning and sequencing of PCR-amplified 16S rRNA gene fragments. DGGE analysis revealed a drastic difference between the genetic structures of the bacterial communities of the termite gut and the mound. Analysis of 266 clones, including 54 from excised bands, revealed a high level of diversity in each biota investigated. The soil-feeding termite mound was dominated by the Actinobacteria phylum, whereas the Firmicutes and Proteobacteria phyla dominate the gut sections of termites and the surrounding soil, respectively. Phylogenetic analyses revealed a distinct clustering of Actinobacteria phylotypes between the mound and the surrounding soil. The Actinobacteria clones of the termite mound were diverse, distributed among 10 distinct families, and like those in the termite gut environment lightly dominated by the Nocardioidaceae family. Our findings confirmed that the soil-feeding termite mound (C. niokoloensis) represents a specific bacterial habitat in the tropics.

Genetic differentiation in the soil-feeding termite Cubitermes sp. affinis subarquatus: occurrence of cryptic species revealed by nuclear and mitochondrial markers

BackgroundSoil-feeding termites are particularly interesting models for studying the effects of fragmentation, a natural or anthropic phenomenon described as promoting genetic differentiation. However, studying the link between fragmentation and genetics requires a method for identifying species unambiguously, especially when morphological diagnostic characters are lacking. In humivorous termites, which contribute to the fertility of tropical soils, molecular taxonomy and phylogenetic relationships are rarely studied, though mitochondrial and nuclear molecular markers are widely used in studies of pest termites. Here, we attempt to clarify the taxonomy of soil-feeding colonies collected throughout the naturally fragmented Lopé Reserve area (Gabon) and morphologically affiliated to Cubitermes sp. affinis subarquatus. The mitochondrial gene of cytochrome oxidase II (COII), the second nuclear rDNA internal transcribed spacer (ITS2) and five microsatellites were analyzed in 19 colonies.ResultsBayesian Inference, Maximum Likelihood and Maximum Parsimony phylogenetic analyses, which were applied to the COII and ITS2 sequences, and Neighbor-Joining reconstructions, applied to the microsatellite data, reveal four major lineages in the Cubitermes sp. affinis subarquatus colonies. The concordant genealogical pattern of these unlinked markers strongly supports the existence of four cryptic species. Three are sympatric in the Reserve and are probably able to disperse within a mosaic of forests of variable ages and savannahs. One is limited to a very restricted gallery forest patch located in the North, outside the Reserve.ConclusionOur survey highlights the value of combined mitochondrial and nuclear markers for exploring unknown groups such as soil-feeding termites, and their relevance for resolving the taxonomy of organisms with ambiguous morphological diagnostic characters.

Functional complement of biogenic structures produced by earthworms, termites and ants in the neotropical savannas

Soil-engineering organisms (earthworms, termites and ants) affect the soil and litter environment indirectly by the accumulation of their biogenic structures (casts, pellets, galleries, crop sheetings nests…). An enzymatic typology was conducted on six types of biogenic structures: casts produced by two earthworms ( Andiodrilus sp. and Martiodrilus sp.), a nest built by a soil-feeding termite ( Spinitermes sp.), crop galleries built by another soil-feeding termite ( Ruptitermes sp.) and soil pellets produced by two species of leaf-cutting ant ( Acromyrmex landolti and Atta laevigata) and an control soil from a natural Colombian savanna. A total of 10 enzymes (xylanase, amylase, cellulase, α-glucosidase, β-glucosidase, β-xylosidase, N-acteyl-glucosaminidase, alkaline and acid phosphatases and laccase) were selected to characterize the functional diversity of the biogenic structures. Our results showed that (i) Martiodrilus casts were characterized by a broad enzymatic profile that was different from that of the soil. (ii) A. laevigata pellets and termite structures had a profile broadly similar to the soil only with some enzymes (iii) Andiodrilus casts had an enzyme profile very similar to that of the soil. These results suggest that the functional diversity of these structures is related to differences between species and not to differences between taxonomic groups. For the first time, we evaluated differences in enzyme typology between biogenic structures collected on the same site but produced by different organisms. These differences suggested species dependent pathways for the decomposition of organic matter.