Lignocellulose degradation by microorganisms from termite hills and termite guts: A survey on the present state of art

Varma, Ajit; Kolli, Bala K.; Paul, Jaishree; Saxena, Shailendra K.; König, Helmut

doi:10.1111/j.1574-6976.1994.tb00120.x

Cited by 78 publications

(50 citation statements)

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“…Termites largely are dependent on gut symbiotes, flagellate protozoa and bacteria, for the digestion of the polysaccharides, such as cellulose and hemicelluloses, comprising a major portion of their food [88]. Those materials and others more resistant to breakdown, such as lignin, also may be processed externally by fungi and other microorganisms present in the nest [145], and converted into easily assimilable form. For example, the carbon to nitrogen (C:N) ratios of undecayed leaf litter and wood, typically 25-100:1 and 200-1200:1, respectively [146,147], are reduced by the white-rot Termitomyces fungi cultivated in the gardens of macrotermitine termites (Termitidae: Macrotermitinae) to values much closer to those of the tissues of the termites themselves (5-10:1 [85,148]).…”

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confidence: 99%

Role of Arthropods in Maintaining Soil Fertility

2013

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Abstract:In terms of species richness, arthropods may represent as much as 85% of the soil fauna. They comprise a large proportion of the meso-and macrofauna of the soil. Within the litter/soil system, five groups are chiefly represented: Isopoda, Myriapoda, Insecta, Acari, and Collembola, the latter two being by far the most abundant and diverse. Arthropods function on two of the three broad levels of organization of the soil food web: they are plant litter transformers or ecosystem engineers. Litter transformers fragment, or comminute, and humidify ingested plant debris, which is deposited in feces for further decomposition by micro-organisms, and foster the growth and dispersal of microbial populations. Large quantities of annual litter input may be processed (e.g., up to 60% by termites). The comminuted plant matter in feces presents an increased surface area to attack by micro-organisms, which, through the process of mineralization, convert its organic nutrients into simpler, inorganic compounds available to plants. Ecosystem engineers alter soil structure, mineral and organic matter composition, and hydrology. The burrowing by arthropods, particularly the subterranean network of tunnels and galleries that comprise termite and ant nests, improves soil porosity to provide adequate aeration and water-holding capacity below ground, facilitate root penetration, and prevent surface crusting and erosion of topsoil. Also, the movement of particles from lower horizons to the surface by ants and termites aids in mixing the organic and mineral fractions of the soil. The feces of arthropods are the basis for the formation of soil aggregates and humus, which physically stabilize the soil and increase its capacity to store nutrients.

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Section: +mentioning

confidence: 99%

Role of Arthropods in Maintaining Soil Fertility

2013

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“…In the digestive tracts of lower termites, cellulose seems to be synergistically degraded by flagellates, bacteria, and yeasts (3,7,15) as well as by the termiteЈs own cellulases (14,17). Cellulases of termite origin belong to glycosyl hydrolase family 9 (GHF9).…”

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Termite Gut Symbiotic Archaezoa Are Becoming Living Metabolic Fossils

Fröhlich

Pfeiffer

et al. 2003

Eukaryot Cell

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Over the course of several million years, the eukaryotic gut symbionts of lower termites have become adapted to a cellulolytic environment. Up to now it has been believed that they produce nutriments using their own cellulolytic enzymes for the benefit of their termite host. However, we have now isolated two endoglucanases with similar apparent molecular masses of approximately 36 kDa from the not yet culturable symbiotic Archaezoa living in the hindgut of the most primitive Australian termite, Mastotermes darwiniensis. The N-terminal sequences of these cellulases exhibited significant homology to cellulases of termite origin, which belong to glycosyl hydrolase family 9. The corresponding genes were detected not in the mRNA pool of the flagellates but in the salivary glands of M. darwiniensis. This showed that cellulases isolated from the flagellate cells originated from the termite host. By use of a PCR-based approach, DNAs encoding cellulases belonging to glycosyl hydrolase family 45 were obtained from micromanipulated nuclei of the flagellates Koruga bonita and Deltotrichonympha nana. These results indicated that the intestinal flagellates of M. darwiniensis take up the termite's cellulases from gut contents. K. bonita and D. nana possess at least their own endoglucanase genes, which are still expressed, but without significant enzyme activity in the nutritive vacuole. These findings give the impression that the gut Archaezoa are heading toward a secondary loss of their own endoglucanases and that they use exclusively termite cellulases.Cellulose is the major polysaccharide component of plant cell walls and the most abundant renewable energy source on earth. In the biological conversion of cellulose to glucose, at least three distinct types of glycolytic enzymes are involved. Endoglucanases (endo-1,4-␤-glucanase, EC 3.2.1.4) randomly hydrolyze 1,4-␤ bonds of the cellulose chains. Cellobiohydrolases (exo-1,4-␤-glucanase, EC 3.2.1.91) cleave cellobiosyl units from nonreducing ends of the cellullose chains. ␤-Glucosidases (EC 3.2.1.21) cleave glucosyl units from nonreducing ends of cello-oligosaccharides. The diverse spectra of cellulases are classified into 12 of the 57 glycosyl hydrolase families based on amino acid sequence similarities (5).Termites are among the most important lignocellulose-digesting insects and possess a great variety of symbiotic microorganisms in their hindguts, including Bacteria, Archaea and Eukarya, i.e., protozoa and yeasts (7). In the digestive tracts of lower termites, cellulose seems to be synergistically degraded by flagellates, bacteria, and yeasts (3, 7, 15) as well as by the termiteЈs own cellulases (14, 17). Cellulases of termite origin belong to glycosyl hydrolase family 9 (GHF9). Flagellated protozoa belonging to the Archaezoa are unique symbionts in the phylogenetically lower termites. They are cellulolytic and produce acetate from cellulose for the benefit of their hosts (10). The termite Mastotermes darwiniensis is the only species of the most primitive termite family, M...

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“…One of the habitats of treponemes is the digestive tract of termites and woodeating cockroaches. The diverse microbial gut community of the termites, consisting of bacteria, archaea, yeasts and unique flagellates, is known to support the decomposition of complex organic compounds and thus enables the termites to feed on wood or soil (Eutick et al, 1978;Breznak & Brune, 1994;Varma et al, 1994;König et al, 2002;König & Varma, 2005). Morphologically diverse spirochaetes (0.2-1.0 mm wide and 3-100 mm long) are present consistently in the hindgut of all termites (Breznak, 1984), and they represent one of the most abundant bacterial groups in the gut (Paster et al, 1996).…”

Section: Introductionmentioning

confidence: 99%