Treponema isoptericolens sp nov., a novel spirochaete from the hindgut of the termite Incisitermes tabogae

A novel spirochaete, Treponema sp. strain SPIT5(T), was isolated from hindgut contents of the drywood termite Incisitermes tabogae (Snyder). The cells of strain SPIT5(T) were motile, helical in shape, 0.4-0.5 mu m in diameter and generally 12-20 mu m long. The strain is obligately anaerobic and ferments different mono-, di- and oligosaccharides by forming ethanol as the main liquid fermentation end product. Furthermore, strain SPIT5(T) was able to grow anaerobically with yeast extract as sole carbon and energy source. Fastest growth was obtained at 30 degrees C, the temperature at which the termites were also grown. The optimum pH for growth was 7.2, with a range of pH 6.5-8.0. The cells possessed various enzyme activities that are involved in the degradation of lignocellulose in the termite hindgut, such as beta-D-glucosidase, a-L-arabinosidase and beta-D-xylosidase. The G + C content of the DNA was 47.7 mol%. Based on 16S rRNA gene sequence analysis, strain SPIT5(T) was shown to belong to the so-called 'termite cluster I' of the genus Treponema. The closest relative of strain SPIT5(T) was Treponema primitia ZAS-2(T), with 92.3% sequence similarity. On the basis of its phenotypic and genotypic properties, strain SPIT5(T) can be distinguished from other described species of the genus Treponema. Therefore, strain SPIT5(T) represents a novel species of Treponema, for which the name Treponema isoptericolens sp. nov. is proposed. The type strain is strain SPIT5(T) (=DSIM 18056(T) = JCM 13955(T)).