Genetic diversity of Leptotrichia and description of Leptotrichia goodfellowii sp. nov., Leptotrichia hofstadii sp. nov., Leptotrichia shahii sp. nov. and Leptotrichia wadei sp. nov.

Abstract

Sixty strains of Gram-negative, anaerobic, rod-shaped bacteria from human sources initially assigned to Leptotrichia buccalis (n=58) and ‘Leptotrichia pseudobuccalis’ (n=2) have been subjected to polyphasic taxonomy. Full-length 16S rDNA sequencing, DNA–DNA hybridization, RAPD, SDS-PAGE of whole-cell proteins, cellular fatty acid analysis and enzymic/biochemical tests supported the establishment of four novel Leptotrichia species from this collection, Leptotrichia goodfellowii sp. nov. (type strain LB 57T=CCUG 32286T=CIP 107915T), Leptotrichia hofstadii sp. nov. (type strain LB 23T=CCUG 47504T=CIP 107917T), Leptotrichia shahii sp. nov. (type strain LB 37T=CCUG 47503T=CIP 107916T) and Leptotrichia wadei sp. nov. (type strain LB 16T=CCUG 47505T=CIP 107918T). Light and electron microscopy showed that the four novel species were Gram-negative, non-spore-forming and non-motile rods. L. goodfellowii produced arginine dihydrolase, β-galactosidase, N-acetyl-β-glucosaminidase, arginine arylamidase, leucine arylamidase and histidine arylamidase. L. shahii produced α-arabinosidase. L. buccalis and L. goodfellowii fermented mannose and were β-galactosidase-6-phosphate positive. L. goodfellowii, L. hofstadii and L. wadei were β-haemolytic. L. buccalis fermented raffinose. With L. buccalis, L. goodfellowii showed 3·8–5·5 % DNA–DNA relatedness, L. shahii showed 24·5–34·1 % relatedness, L. hofstadii showed 27·3–36·3 % relatedness and L. wadei showed 24·1–35·9 % relatedness. 16S rDNA sequencing demonstrated that L. hofstadii, L. shahii, L. wadei and L. goodfellowii each formed individual clusters with 97, 96, 94 and 92 % similarity, respectively, to L. buccalis.