Isolation of Desulfovibrio intestinalis sp. nov. from the hindgut' of the lower termite Mastotermes darwiniensis.

A Gram-negative, anaerobic sulfate-reducing bacterium was isolated from hindgut contents of the lower termite Mastotermes darwiniensis Froggatt (strain KMS2). Strain KMS2 is motile by a single polar flagellum. The isolate possesses desulfoviridin and catalase activity. The G+C content of its DNA is in the range of 54.5-55.5 mol% (strain KMS2). It respires hydrogen and different low molecular weight organic compounds in the presence of sulfate, thiosulfate, and sulfite, and also oxygen. The isolated strain ferments pyruvate. Fastest growth with a doubling time of 12.5 h was obtained at 37 degrees C and not at 28 degrees C, the temperature at which the termites were grown. The isolate showed a 16S rDNA sequence homology of 95.9% to Desulfovibrio desulfuricans ATCC 27774 and a DNA-DNA homology of 44.6% to D. desulfuricans Essex 6 (type strain). Based on its biochemical properties and 16S rDNA sequence, the isolate was assigned to a new species named Desulfovibrio intestinalis.

Degradation of dimeric lignin model compounds by aerobic bacteria isolated from the hindgut of xylophagous termites.

The capability of the intestinal flora from the gut of xylophagous termites of degrading lignin model compounds was investigated. Different dimeric lignin model compounds-degrading bacteria were obtained from the hindgut flora of Mastotermes darwiniensis Froggatt, Reticulitermes santonensis Feytaud, Nasutitermes nigriceps Haldeman and Zootermopsis angusticollis Hagen. In the presence of oxygen dimeric model compounds were degraded by all isolates. This indicates that the hindgut flora of termites is basically able to produce substrate for their host from aromatic extractives of wood.

Hemicellulose-degrading bacteria and yeasts from the termite gut.

Termites play a major role in the recycling of photosynthetically fixed carbon. With the aid of their symbiotic intestinal flora, they are able to degrade extensively wood constituents such as cellulose and hemicellulose. Nevertheless, the microbial species involved in the degradation of hemicelluloses are poorly defined. The purpose of this paper was to examine the microflora involved in hemicellulose degradation. Different aerobic and facultatively anaerobic bacteria and yeasts were isolated using xylan, arabinogalactan and carboxymethylcellulose as substrates. Gram-positive isolates belonged to the genera Bacillus, Paenibacillus, Streptomyces or the actinobacteria group, while the Gram-negative strains were assigned to the genera Pseudomonas, Acinetobacter, Ochrobactrum, and to genera belonging to the family Enterobacteriaceae. The spectrum and activity of xylan- and arabinogalactan-hydrolysing glycosidases of these new isolates, together with additional bacterial strains originally obtained from enrichments with aromatic compounds were determined.

Bacillus oleronius sp.nov., a member of the hindgut flora of the termite Reticulitermes santonensis (Feytaud).

A new rod-shaped endospore-forming bacterium is described, which was isolated from the hindgut of the termite Reticulitermes santonensis (Feytaud). The isolate stains Gram negative and its DNA has a guanine-plus-cytosine content of 35 mol%. Despite the Gram-staining reaction, both biochemical and physiological features place the isolate in the genus Bacillus and indicate a phenotypic resemblance to the Bacillus firmus-lentus group of species. On the basis of comparative 16S rRNA analysis and some phenotypic features the isolate clearly represents a new species for which the name Bacillus oleronius is proposed. The type strain is Bacillus oleronius Rt 10 (DSM 9356).