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Andreas Brune - One of the best experts on this subject based on the ideXlab platform.
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the complete mitogenomes of six higher termite species reconstructed from metagenomic datasets cornitermes sp Cubitermes ugandensis microcerotermes parvus nasutitermes corniger neocapritermes taracua and termes hospes
Mitochondrial DNA, 2016Co-Authors: Carsten Dietrich, Andreas BruneAbstract:We reconstructed the complete mitochondrial genomes of six higher termite species from metagenomic datasets of their isolated hindgut compartments. The sequencing reads were retrieved and assembled with the mitochondrial-baiting and iterative-mapping algorithm (MITObim), which yielded closed mitogenomes without additional finishing efforts (average coverage ranging from 2300- to 17,000-fold). The genomes ranged from 16.1 to 17.6 kbp in size and had G+C contents between 32 and 35 mol%; each contained the same 37 genes present also in the mitochondria of other termite species. Our study substantially increases the number of termite mitogenomes available for phylogenetic studies and offers a facile strategy for identifying host species in metagenomic studies of their associated microbiota.
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methanoplasmatales thermoplasmatales related archaea in termite guts and other environments are the seventh order of methanogens
Applied and Environmental Microbiology, 2012Co-Authors: Kristina Paul, James Nonoh, Lena Mikulski, Andreas BruneAbstract:The Euryarchaeota comprise both methanogenic and nonmethanogenic orders and many lineages of uncultivated archaea with unknown properties. One of these deep-branching lineages, distantly related to the Thermoplasmatales, has been discovered in various environments, including marine habitats, soil, and also the intestinal tracts of termites and mammals. By comparative phylogenetic analysis, we connected this lineage of 16S rRNA genes to a large clade of unknown mcrA gene sequences, a functional marker for methanogenesis, obtained from the same habitats. The identical topologies of 16S rRNA and mcrA gene trees and the perfect congruence of all branches, including several novel groups that we obtained from the guts of termites and cockroaches, strongly suggested that they stem from the same microorganisms. This was further corroborated by two highly enriched cultures of closely related methanogens from the guts of a higher termite (Cubitermes ugandensis) and a millipede (Anadenobolus sp.), which represented one of the arthropod-specific clusters in the respective trees. Numerous other pairs of habitat-specific sequence clusters were obtained from the guts of other termites and cockroaches but were also found in previously published data sets from the intestinal tracts of mammals (e.g., rumen cluster C) and other environments. Together with the recently described Methanomassiliicoccus luminyensis isolated from human feces, which falls into rice cluster III, the results of our study strongly support the idea that the entire clade of “uncultured Thermoplasmatales” in fact represents the seventh order of methanogenic archaea, for which the provisional name “Methanoplasmatales” is proposed.
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nitrate reduction nitrous oxide formation and anaerobic ammonia oxidation to nitrite in the gut of soil feeding termites Cubitermes and ophiotermes spp
Environmental Microbiology, 2012Co-Authors: David Kamanda Ngugi, Andreas BruneAbstract:Soil-feeding termites play important roles in the dynamics of carbon and nitrogen in tropical soils. Through the mineralization of nitrogenous humus components, their intestinal tracts accumulate enormous amounts of ammonia, and nitrate and nitrite concentrations are several orders of magnitude above those in the ingested soil. Here, we studied the metabolism of nitrate in the different gut compartments of two Cubitermes and one Ophiotermes species using (15)N isotope tracer analysis. Living termites emitted N(2) at rates ranging from 3.8 to 6.8 nmol h(-1) (g fresh wt.)(-1). However, in homogenates of individual gut sections, denitrification was restricted to the posterior hindgut, whereas nitrate ammonification occurred in all gut compartments and was the prevailing process in the anterior gut. Potential rates of nitrate ammonification for the entire intestinal tract were tenfold higher than those of denitrification, implying that ammonification is the major sink for ingested nitrate in the intestinal tract of soil-feeding termites. Because nitrate is efficiently reduced already in the anterior gut, reductive processes in the posterior gut compartments must be fuelled by an endogenous source of oxidized nitrogen species. Quite unexpectedly, we observed an anaerobic oxidation of (15)N-labelled ammonia to nitrite, especially in the P4 section, which is presumably driven by ferric iron; nitrification and anammox activities were not detected. Two of the termite species also emitted substantial amounts of N(2) O, ranging from 0.4 to 3.9 nmol h(-1) (g fresh wt.)(-1), providing direct evidence that soil-feeding termites are a hitherto unrecognized source of this greenhouse gas in tropical soils.
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novel lineages of planctomycetes densely colonize the alkaline gut of soil feeding termites Cubitermes spp
Environmental Microbiology, 2008Co-Authors: Tim Kohler, Ulrich Stingl, Katja Meuser, Andreas BruneAbstract:Summary Members of the phylum Planctomycetes are found in aquatic and terrestrial habitats. Here we show that the highest density of Planctomycetes in natural environments (2.6 × 109 cells ml−1) is encountered in the hindgut of soil-feeding termites (Cubitermes spp.), where they constitute up to one-third of the bacteria in the alkaline P3 compartment detected by fluorescent in situ hybridization (FISH). A 16S-rRNA-based approach revealed that the planctomycete community is very diverse and falls into three major clusters representing novel, deeply branching lineages. Terminal restriction fragment length polymorphism (T-RFLP) analysis and FISH with cluster-specific oligonucleotide probes confirmed that most of the lineages are also present in other gut compartments, albeit in much lower numbers, but absent from the food soil. The majority of planctomycetes in the gut belong to a large clade, the ‘Termite planctomycete cluster’, which consists exclusively of clones from termite guts and seems to be represented in all termite species.
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phylogenetic diversity abundance and axial distribution of bacteria in the intestinal tract of two soil feeding termites Cubitermes spp
Applied and Environmental Microbiology, 2003Co-Authors: Dirk Schmittwagner, Michael W Friedrich, Bianca Wagner, Andreas BruneAbstract:The hindgut of soil-feeding termites is highly compartmentalized and characterized by pronounced axial dynamics of the intestinal pH and microbial processes such as hydrogen production, methanogenesis, and reductive acetogenesis. Nothing is known about the bacterial diversity and the abundance or axial distribution of the major phylogenetic groups in the different gut compartments. In this study, we showed that the variety of physicochemical conditions is reflected in the diversity of the microbial communities in the different gut compartments of two Cubitermes species (Termitidae: Termitinae). 16S rRNA gene clones from the highly alkaline first proctodeal segment (P1) of Cubitermes orthognathus represented almost exclusively gram-positive bacteria with low G+C content (LGC bacteria). In the posterior gut segments, their proportion decreased progressively, and the clone libraries comprised a variety of phyla, including the Cytophaga-Flexibacter-Bacteroides group, various subgroups of Proteobacteria, and the spirochetes. Phylogenetic analysis revealed that many of the clones clustered with sequences from the guts of other termites, and some even formed clusters containing only clones from C. orthognathus. The abundance and axial distribution of major phylogenetic groups in the gut of Cubitermes ugandensis were determined by fluorescence in situ hybridization with group-specific oligonucleotide probes. While the results were generally in good agreement with those of the clonal analysis, direct counts with probes specific for the Planctomycetales revealed a severe underestimation of representatives of this phylum in the clone libraries. Results obtained with newly designed FISH probes directed against two clusters of LGC clones from C. orthognathus indicated that the clones were restricted to specific gut regions. A molecular fingerprinting analysis published in a companion paper (D. Schmitt-Wagner, M. W. Friedrich, B. Wagner, and A. Brune, Appl. Environ. Microbiol. 69:6018-6024, 2003) corroborated the presence of compartment-specific bacterial communities in the gut of different Cubitermes species.
Myriam Harry - One of the best experts on this subject based on the ideXlab platform.
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The distribution of Wolbachia in Cubitermes (Termitidae, Termitinae) castes and colonies: a modelling approach.
PloS one, 2015Co-Authors: Virginie Roy, Marc Girondot, Myriam HarryAbstract:Wolbachia are endosymbiotic bacteria of arthropods and nematodes that are able to manipulate host reproduction. Although vertically transmitted via the cytoplasm in eggs, horizontal transmission of Wolbachia among and within arthropod species has been shown to be common. Eusocial insects represent interesting models for studying Wolbachia transmission due to colonial organization and close interaction between nestmates. Here we conducted a detailed screening of Wolbachia infection for 15 colonies of the very common soil-feeding termites Cubitermes spp. affinis subarquatus (Termitidae, Termitinae) that consist of four distinct phylogenetic species in the Lope forest Reserve, Gabon. Infection tests showed that 50% of the individuals were Wolbachia positive (N = 555) with 90% of reproductives and 48% of offspring infected. White soldiers, which are transitional stages preceding mature soldiers, had a significantly higher mean infection rate (74%) than the other castes and stages (63%, 33% and 39% for larvae, workers and mature soldiers, respectively). We used a maximum likelihood method and Akaike’s Information Criterion in order to explain the non-expected high rate of Wolbachia infection in white soldiers. The best model included a species effect for the stochastic loss of Wolbachia and a caste effect for the rate of gain. After fitting, the best model selected was for a species-specific rate of loss with a null rate of new gain for larvae, workers and soldiers and a probability of 0.72 whatever the species, that a white soldier becomes newly contaminated during that stage. The mean expected infection rate in white soldiers without a new gain was estimated to 17% instead of the 74% observed. Here we discuss the possible explanations to the high infection rate observed in white soldiers.
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parentage analysis in gabonese colonies of soil feeding termites belonging to the Cubitermes sp affinis subarquatus complex of species termitidae termitinae
Insect Science, 2010Co-Authors: Virginie Roy, Lise Dupont, Myriam HarryAbstract:Cubitermes spp. are widely distributed soil-feeding termite species in sub-Saharan Africa which play a fundamental role in soil structure and fertility. A complex of at least four cryptic species (i.e., Cubitermes sp. affinis subarquatus complex of species) has been recently described using molecular markers. In order to investigate the breeding system of these species, five microsatellite markers were used to carry out parentage and relatedness analyses in 15 Gabonese colonies. Monogamy was confirmed as the predominant reproductive organization in Cubitermes spp. (76% of the colonies). Within 30% of these monogamous colonies, a high relatedness between reproductives was shown, suggesting that mating between related individuals occurs. However, Cubitermes colonies can deviate from monogamy. Indeed, parental contributions by at least two related reproductives of the same sex were revealed in four colonies and polyandry was demonstrated in two of them. Infiltration of reproductives in the colony is the most plausible explanation for such cases of polygamy in Cubitermes spp.
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diversity of wolbachia isolated from the Cubitermes sp affinis subarquatus complex of species termitidae revealed by multigene phylogenies
Fems Microbiology Letters, 2007Co-Authors: Virginie Roy, Myriam HarryAbstract:Wolbachia are endosymbiotic bacteria that may alter the reproductive mechanisms of arthropod hosts. Eusocial termites provide considerable scope for Wolbachia studies owing to their ancient origin, their great diversity and their considerable ecological, biological and behavioral plasticity. This article describes the phylogenetic distribution of Wolbachia infecting termites of the Cubitermes genus, which are particularly abundant soil-feeders in equatorial Africa. Fourteen colonies of the Cubitermes sp. affinis subarquatus complex of species were screened using five bacterial genes (wsp, ftsZ, coxA, fbpA and 16S rRNA genes) and a striking diversity of Wolbachia strains was identified within these closely related species. In the host complex, three Wolbachia variants were found that were not in the super groups usually reported for termites (F and H), each infecting one or two Cubitermes species.
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genetic differentiation in the soil feeding termite Cubitermes sp affinis subarquatus occurrence of cryptic species revealed by nuclear and mitochondrial markers
BMC Evolutionary Biology, 2006Co-Authors: Virginie Roy, Christine Demanche, Alexandre Livet, Myriam HarryAbstract:Background Soil-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 Lope 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.
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microsatellite markers in soil feeding termites Cubitermes subarquatus isoptera termitidae termitinae
Molecular Ecology Notes, 2001Co-Authors: Myriam Harry, C L Roose, E Garniersillam, Michel SolignacAbstract:Seven microsatellite markers were isolated from Cubitermes subarquatus belonging to the soil-feeding termite trophic group that plays a key role in tropical rain forests. A variability study performed by using a population of C. subarquatus ( n = 73) sampled in the La Lope forest reserve (Gabon) from 42 nests revealed from 4 to 12 alleles per locus and an heterozygosity from 0.28 to 0.84. Tests for cross-species amplification realized in the sympatric C. intercalatus and in eight other sympatric termite genera indicated a wider application of the primers isolated from Cubitermes in soil-feeding termites.
D E Bignell - One of the best experts on this subject based on the ideXlab platform.
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pyrolysis mass spectrometry confirms enrichment of lignin in the faeces of a wood feeding termite zootermopsis nevadensis and depletion of peptides in a soil feeder Cubitermes ugandensis
Soil Biology & Biochemistry, 2013Co-Authors: B S Griffiths, J M Bracewell, G W Robertson, D E BignellAbstract:Changes in biopolymer products during transit of the intestine in two termites with contrasting feeding habits were quantified by pyrolysis mass-spectrometry. In Zootermopsis nevadensis, a wood-feeder, native lignin-derived fractions increased in the faeces, with little indication of modification or degradation, but 62% of hexose polymer and 43% of xylan were degraded. In the soil-feeding Cubitermes ugandensis, polysaccharide and alkene-derived mass ions were enriched in faeces while amino acid-derived ions were depleted, consistent with a proposed model of fermentative digestion supported by peptides released from soil organic matter.
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structure microbial associations and function of the so called mixed segment of the gut in two soil feeding termites proCubitermes aburiensis and Cubitermes severus termitidae termitinae
Journal of Zoology, 2009Co-Authors: D E Bignell, J M Anderson, H Oskarsson, P Ineson, T G WoodAbstract:The morphology, histology and ultrastructure of the mesenteric and proctodaeal components of the mixed segment are described in detail, together with the disposition of the associated gut musculature, the patterns of peristalsis and the streaming movements of soil particles in the gut lumen. The mesenteric epithelium is characterized by very extensive basal infoldings which are associated with a large population of mitochondria, but evidence of significant protein synthesis and secretion is lacking. It is proposed that this tissue is a transporting epithelium whose major function is the secretion of a copious, K+ -rich fluid into the intestinal lumen to irrigate the hindgut (proctodaeum) and that alkaline hydrolysis of humic fractions by this fluid is an essential component of digestion. Malpighian tubules are present, but do not participate in fluid excretion. Since the hind-guts of soil-feeding termites are exceptionally voluminous and elongated and the major symbiotic micro-organisms occupy fixed positions by virtue of their attachment to the lining cuticle, it is argued that flushing is necessary to sustain microbial activity and for the recovery of end-products by the host. A survey of the protodaeal epithelium suggests that the anterior colon (P4a) is the most likely site of fluid reabsorption and that the wall of the hindgut anterior to this site is impermeable. The greater degree of ultrastructural differentiation of the mixed segment of Cubitermes severus and its more complete morphological separation from the midgut suggests that this species is a more advanced soil-feeder than ProCubitermes aburiensis.
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on the respiratory quotient rq of termites insecta isoptera
Journal of Insect Physiology, 1997Co-Authors: Lina Nunes, D E Bignell, Paul EggletonAbstract:Abstract The respiratory quotient (RQ) at 28°C was determined by Warburg manometry in 23 species of termites from the Mbalmayo Forest Reserve (Cameroon) and three sub-tropical species cultured under laboratory conditions in the U.K. or freshly collected in Australia. The data are tabulated with other recently reported RQs (determined by manometry or GC) and with measured CH4 emission rates to provide a survey of 29 species covering both lower and higher termites in all major trophic (functional) categories. In all species, except the wood-feeding Coptotermes acinaciformis and the soil-feeding Cubitermes fungifaber, the observed mean values (with manometry corrected for known fluxes of H2 and CH4) were at or well above 1.00. Soil-feeding forms (except C. fungifaber) generally showed a high apparent RQ (not corrected for H2), with nine species (out of 13) above 1.20 and six species above 1.30. Well-replicated laboratory experiments with Reticulitermes lucifugus showed that there was a tendency for RQ to fall with time over a 4-h incubation, although remaining greater than 1.00. The observed RQs are consistent with carbohydrate being the principal substrate supporting respiration in all trophic and taxonomic categories, with little or no contribution from the degradation of lignin or other polyaromatic materials. However, in many species (especially soil-feeders), the observed RQ is greater than that expected from known fluxes of O2, CO2 and CH4 on the assumption that carbohydrate is the respiratory substrate. This presupposes that there is a large hydrogen sink (additional to CH4 production), possibly the emission of H2 gas, and/or the existence of unresolved digestive mechanisms or electron routings. Uncertainties in the use of manometry with termites are discussed.
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isolation of facultatively aerobic actinomycetes from the gut parent soil and mound materials of the termites proCubitermes aburiensis and Cubitermes severus
Fems Microbiology Letters, 1991Co-Authors: D E Bignell, J M Anderson, R ChosseAbstract:Isolates of the genus Streptomyces were readily obtained from the intestines of two African species of soil-feeding termites by an aerobic explant technique using starch casein medium, and from their parent soil and mound materials by dilution plating. Discriminant analysis of the isolates, based on 44 representative characters, showed that the population derived directly from the termites was significantly different from that of the feed soil or the mound. The termite gut was considered to be a good source of unusual actinomycetes, but strains isolated under aerobic conditions are likely to be allochthons selected by the intestinal environment, which is highly alkaline and anaerobic. An anaerobic, filamentous isolate was obtained which may be a component of the prokaryotic symbiont population mediating termite digestion.
Alain Brauman - One of the best experts on this subject based on the ideXlab platform.
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differences between bacterial communities in the gut of a soil feeding termite Cubitermes niokoloensis and its mounds
Applied and Environmental Microbiology, 2007Co-Authors: Saliou Fall, J L Chotte, Jerome Hamelin, Farma Ndiaye, Komi Assigbetse, Michel Aragno, Alain BraumanAbstract: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.
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the effect of the soil feeding termite Cubitermes niokoloensis on soil microbial activity in a semi arid savanna in west africa
Plant and Soil, 2004Co-Authors: Diogou Ndiaye, Michel Lepage, R Lensi, Alain BraumanAbstract:Soil-feeding termite mounds are an important, highly specific soil microbial compartment in semi-arid savannas. The aim of this study was to determine the role of these mounds in organic matter dynamics, taking the soil nitrogen cycle as representative of microbial mediated activity. Measures of microbial activity (soil respiration) and aspects of the nitrogen cycle (arginine ammonification, nitrification and denitrification) were made in the mound of Cubitermes niokoloensis, a representative species of the soil-feeding guild in dry savanna. Simultaneous measurements were made of mineral nitrogen concentration, total bacterial count (using AODC) and denitrifying and nitrifying bacterial densities. All measurements were made in two different compartments of the mound, the internal and external walls. Although organic matter was richer and there was a significant higher density of bacteria in the internal wall of the mound (by a factor of 2), the metabolic activity in this compartment was not significantly different from the surrounding savanna soil. This was not true for the external wall of the mound, suggesting that there was a difference in oxygen availability between these two compartments. Compared to the reference savanna soil, the mound was a hot spot of mineral nitrogen (100-times NH4 + and 50-times NO3 −) representing 25% of the total nitrogen content of the mound, compared with only 2% in the savanna soil. This high level of mineral nitrogen was associated with a higher density of denitrifying bacteria and increased denitrification and ammonification potentials (3 and 4 times, respectively) in the mound compartments compared with the reference soil. However, the specific activity of the denitrifying bacteria was lower in the internal wall of the mound than in the reference soil. Also, no potential nitrification was observed in the mound, demonstrating a serious perturbation of the nitrogen cycle induced by the soil-feeding termite C. niokoloensis in the sandy savanna soil, with, as a consequence, an enrichment in organic matter and nutrients for plants. This study reinforces the view of termites as soil engineers in semi-arid savannas, modifying their environment in both of its biotic and abiotic components.
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impact of a soil feeding termite Cubitermes niokoloensis on the symbiotic microflora associated with a fallow leguminous plant crotalaria ochroleuca
Biology and Fertility of Soils, 2003Co-Authors: Daouda N Diaye, Robin Duponnois, Alain Brauman, Michel LepageAbstract:The influence of a soil-feeding termite nest (Cubitermes nikoloensis) on the development of a symbiotic microflora (rhizobia, arbuscular mycorrhizas) was tested in a pot experiment with a tropical legume (Crotalaria ochroleuca). Our results confirmed the role of soil-feeding termite nests as sites of high nutrient concentration, as a significantly higher content of available P and mineral-N was found in the mound wall. Arbuscular mycorrhizal spores increased in the soil near the termite mound. The mound soil itself almost totally depressed mycorrhizal establishment. The positive effect of the soils close to the mound was also evidenced by the number of nodules per root system as well as the nodule biomass per legume plant grown on this medium. Better growth of Crotalaria seedlings was observed in the soils from the mound wall; the shoot biomass increased by a factor of 9 and the root biomass by a factor of 6 as compared to the control soil (10 m away from the mound). Plant growth on soils from the immediate vicinity of the mound showed intermediate results but a higher N content per biomass unit. This probably reflected the association with arbuscular mycorrhiza and rhizobia. This work evidenced the linkage of plant nutrition to nutrient availability in mound material and the indirect mediating effect of the symbiotic microflora.
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comparative distribution of organic matter in particle and aggregate size fractions in the mounds of termites with different feeding habits in senegal Cubitermes niokoloensis and macrotermes bellicosus
Applied Soil Ecology, 2001Co-Authors: Saliou Fall, Alain Brauman, J L ChotteAbstract:Abstract The comparative distribution of organic components in different soil fractions as a result of the activities of two of the most representative species of termites (Cubitermes niokoloensis and Macrotermes bellicosus) in the semi-arid savanna of Senegal was assessed by physical fractionation. The impact of these two species on soil organic matter (SOM) differed. For the soil feeding C. niokoloensis, the internal and external wall of the mound contained five times higher carbon and 10 times higher nitrogen concentrations than the reference soil. In contrast, the mounds of the fungus-growing M. bellicosus had lower C content than the reference soil. Although both species select fine soil particles for mound construction, their strategy differs. Particle-size fractions finer than 50 μm represented 75% of the total mass of soil sampled from the internal and external walls of the mound of soil feeding termites, while clay size particles were the most abundant fraction of these compartments of the fungus growing mound. For the soil feeding species, the particle-size fractions contained 3–10 times higher C concentrations than the fractions isolated from the reference soil, the enrichment being the highest for clay fractions. About 60% of these clay particles remained aggregated within the coarser structures of the silt (2–50 μm) and the sand size particles (50–200 μm). The latter represented 60% of the total soil mass and contained 50% of the total carbon. No impact of M. bellicosus on soil aggregation was recorded. These results clearly reveal the contrasting effects (positive for soil feeding, negative for fungus feeder) of these two species on SOM dynamics. The use of the aggregate fraction of the coarse silt size (20–50 μm) as an indicator of the activity of soil feeding termites is suggested.
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clostridium mayombei sp nov an h2 co2 acetogenic bacterium from the gut of the african soil feeding termite Cubitermes speciosus
Archives of Microbiology, 1991Co-Authors: Matthew D Kane, Alain Brauman, John A BreznakAbstract:Clostridium mayombei sp. nov., a previously undescribed H2-oxidizing CO2-reducing acetogenic bacterium, was isolated from gut contents of the African soilfeeding termite, Cubitermes speciosus. Cells were anaerobic, Gram positive, catalase and oxidase negative, endospore-forming motile rods which measured 1×2 – 6 μm and which had a DNA base composition of 25.6 mol% G+C (strain SFC-5). Optimum conditions for growth on H2+CO2 were at 33°C and pH 7.3, and under these conditions cells produced acetate according to the equation: 4 H2+2 CO2→CH3COOH+2 H2O. Other substrates supporting good growth included carbohydrates (e.g. glucose, xylose, starch), sugar alcohols, and organic and amino acids, and with these substrates acetate was almost always the principle fermentation product. Comparative analysis of 16S rRNA nucleotide sequences confirmed that C. mayombei was closely related to various members of the genus Clostridium. However, morphological and physiological differences between C. mayombei and other homoacetogenic clostridia were deemed significant enough to warrant creation of a new taxon. Results are discussed in light of the diversity of H2/CO2 acetogens recently isolated from various termites, and in terms of the relative importance of H2/CO2 acetogenesis to termite nutrition.
Michel Lepage - One of the best experts on this subject based on the ideXlab platform.
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Effects of controlled livestock grazing and annual prescribed fire on epigeal termite mounds in a savannah woodland in Burkina Faso
Insectes Sociaux, 2008Co-Authors: Saran Traoré, Michel LepageAbstract:The diversity and abundance of epigeal termite mounds were investigated in response to controlled livestock grazing and annual prescribed fire in a Sudanian savannah-woodland in Tiogo State Forest. Sampling of termite mounds was carried out in 4×4 subplots of 0.25 ha in a split-plot experimental design during the rainy season in 2002. There were two main plots of which one was fenced to exclude livestock grazing and the second exposed to grazing. Each of the main plots included 4 subplots with annual prescribed fire since 1992 and 4 subplots without fire. Data were collected on the number and characteristics of termite mounds. A mean density of 698 mounds ha−1 was recorded. Mounds built by Trinervitermes spp. were the most abundant followed by Cubitermes spp., Macrotermes subhyalinus and M. bellicosus. The large mound-builders Macrotermes spp. dominated the community interms of basal area (96% of the total) and above-ground volume (99%). The diversity of mound types was notaffected by livestock grazing and annual early prescribed fire (P>0.05). There was no statistical effect of livestock grazing on mound density, whereas a strong depressive effect of annual fire was observed for Trinervitermes spp. mound density (P=0.012). In this ecosystem, annual prescribed fire appeared to be the major determinant for termite mound abundance.
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Effect of different termite feeding groups on P sorption and P availability in African and South American savannas
Biology and Fertility of Soils, 2006Co-Authors: Danilo López-hernández, Michel Brossard, Jean-claude Fardeau, Michel LepageAbstract:Nest structures of six termite species, four with epigeous (above-ground) and two with subterranean nests were analysed to find out how their building and feeding habits could be related to their nests phosphorus status compared with control soils. Termite nest structure was found to affect significantly the P status in savanna soils: mounds of the African Trinervitermes geminatus and the South American Nasutitermes ephratae (both grass-feeders) displayed a greater amount of available P, especially in the inner part of the nest, than the surrounding soil. The abundant quantities of dead grass material stored in the mound can explain the available soil P increase. A similar increase in P availability was also found for the soil-feeder Cubitermes severus . In mounds of Macrotermes bellicosus , on the other hand, there was a drastic increase in P sorption (and a corresponding decrease in available P) compared to adjacent soils, which was attributed to the building strategy of this species. M. bellicosus selected clay from subsoil to build its nest structure. The data obtained for the subterranean species Ancistrotermes cavithorax and Microtermes toumodiensis indicated also that there is an increase in P sorption in mounds when compared with associated topsoils. Consequently, the nest structures of only certain termite species should be considered, and utilised, as a soil amendment in place of fertilisers. This impact on the P cycle in savannas seems to be related to the termite feeding status and to the type of material utilised in nest building. This should be taken into account before using termite nest material in soil fertility status improvement.
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functional diversity of soil microbial community rock phosphate dissolution and growth of acacia seyal as influenced by grass litter and soil feeding termite nest structure amendments
Geoderma, 2005Co-Authors: Robin Duponnois, M Paugy, Jean Thioulouse, Dominique Masse, Michel LepageAbstract:We tested termite mound materials belonging to different feeding groups: Cubitermes (soil-feeder), Trinervitermes (grass-feeder) and Macrotermes (litter-feeder), as natural microbial inoculum to promote plant growth and increase nutrient supplies from soil organic matter and inorganic amendments (rock phosphate), through their effects on soil microorganisms (functional diversity of soil microflora, arbuscular mycorrhizal fungi, rhizobia, fluorescent pseudomonads, actinomycetes and saprophytic fungi). Experiments were made in a pot experiment with Acacia seyal, a leguminous tree abundant in West Africa, with a sandy soil amended or not with rock phosphate. Results indicated a stimulation of plant growth with Cubitermes and Trinervitermes mound powder (plant height and shoot biomass), similar to what was obtained with rock phosphate alone. Leaf content in N was also increased in the termite treatments (except in Macrotermes soil), whereas mycorrhizal colonization was inhibited as compared to the control. The development of saprophytic fungi was significantly higher in the soils amended with rock phosphate and this effect was hypothesized to be related to the production of large quantities of oxalic acid by fungal populations. The fluorescent pseudomonad populations notably increased in the soils dually amended with mound powders and rock phosphate, and this could be due to the fact that some species of this bacterial group are able to dissolve rock phosphate. The organic and inorganic amendments decreased the soil catabolic evenness in all the mound powder treatments. Among the mound materials tested, Cubitermes mound powder had the most promising effect, especially on SIR response to oxalate. It is concluded that soils amended both with rock phosphate and Cubitermes mound soil could promote the development of microbial communities, which could help to metabolize this compound and consequently enhance plant growth.
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the effect of the soil feeding termite Cubitermes niokoloensis on soil microbial activity in a semi arid savanna in west africa
Plant and Soil, 2004Co-Authors: Diogou Ndiaye, Michel Lepage, R Lensi, Alain BraumanAbstract:Soil-feeding termite mounds are an important, highly specific soil microbial compartment in semi-arid savannas. The aim of this study was to determine the role of these mounds in organic matter dynamics, taking the soil nitrogen cycle as representative of microbial mediated activity. Measures of microbial activity (soil respiration) and aspects of the nitrogen cycle (arginine ammonification, nitrification and denitrification) were made in the mound of Cubitermes niokoloensis, a representative species of the soil-feeding guild in dry savanna. Simultaneous measurements were made of mineral nitrogen concentration, total bacterial count (using AODC) and denitrifying and nitrifying bacterial densities. All measurements were made in two different compartments of the mound, the internal and external walls. Although organic matter was richer and there was a significant higher density of bacteria in the internal wall of the mound (by a factor of 2), the metabolic activity in this compartment was not significantly different from the surrounding savanna soil. This was not true for the external wall of the mound, suggesting that there was a difference in oxygen availability between these two compartments. Compared to the reference savanna soil, the mound was a hot spot of mineral nitrogen (100-times NH4 + and 50-times NO3 −) representing 25% of the total nitrogen content of the mound, compared with only 2% in the savanna soil. This high level of mineral nitrogen was associated with a higher density of denitrifying bacteria and increased denitrification and ammonification potentials (3 and 4 times, respectively) in the mound compartments compared with the reference soil. However, the specific activity of the denitrifying bacteria was lower in the internal wall of the mound than in the reference soil. Also, no potential nitrification was observed in the mound, demonstrating a serious perturbation of the nitrogen cycle induced by the soil-feeding termite C. niokoloensis in the sandy savanna soil, with, as a consequence, an enrichment in organic matter and nutrients for plants. This study reinforces the view of termites as soil engineers in semi-arid savannas, modifying their environment in both of its biotic and abiotic components.
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impact of a soil feeding termite Cubitermes niokoloensis on the symbiotic microflora associated with a fallow leguminous plant crotalaria ochroleuca
Biology and Fertility of Soils, 2003Co-Authors: Daouda N Diaye, Robin Duponnois, Alain Brauman, Michel LepageAbstract:The influence of a soil-feeding termite nest (Cubitermes nikoloensis) on the development of a symbiotic microflora (rhizobia, arbuscular mycorrhizas) was tested in a pot experiment with a tropical legume (Crotalaria ochroleuca). Our results confirmed the role of soil-feeding termite nests as sites of high nutrient concentration, as a significantly higher content of available P and mineral-N was found in the mound wall. Arbuscular mycorrhizal spores increased in the soil near the termite mound. The mound soil itself almost totally depressed mycorrhizal establishment. The positive effect of the soils close to the mound was also evidenced by the number of nodules per root system as well as the nodule biomass per legume plant grown on this medium. Better growth of Crotalaria seedlings was observed in the soils from the mound wall; the shoot biomass increased by a factor of 9 and the root biomass by a factor of 6 as compared to the control soil (10 m away from the mound). Plant growth on soils from the immediate vicinity of the mound showed intermediate results but a higher N content per biomass unit. This probably reflected the association with arbuscular mycorrhiza and rhizobia. This work evidenced the linkage of plant nutrition to nutrient availability in mound material and the indirect mediating effect of the symbiotic microflora.