Dyella telluris sp. nov. and Dyella acidiphila sp. nov., isolated from forest soil of Dinghushan Biosphere Reserve, China

Abstract

Cells of bacterial strains G9T and 7MK23T, isolated from forest soil samples collected from the Dinghushan Biosphere Reserve, Guangdong Province, PR China, were Gram-stain-negative, aerobic and rod-shaped. Strain G9T was motile with single polar flagellum and grew at 12–37 °C (optimum, 28 °C), pH 4.5–8.0 (optimum, pH 6.0–7.5) and in the presence of 0–3.5 % NaCl (optimum, 1.5%, w/v); while strain 7MK23T was non-motile and grew at 12–42 °C (optimum, 28–33 °C), pH 2.5–8.5 (optimum, pH 4.5–6.5) and NaCl levels of 0–1.0 % (optimum, 0–0.5 %, w/v). Phylogenetic analysis based on 16S rRNA gene sequences revealed that both isolates fell within the cluster of the genus Dyella . The closely related species (with a 16S rRNA gene sequence similarity >98.65%) of strain G9T were Dyella terrae JS14-6T (99.0 %), D . kyungheensis THG-B117T (98.8 %) and D . amyloliquefaciens DHC06T (98.7 %) while that of strain 7MK23T were D . mobilis DHON07T (99.2 %) and D . flava DHOC52T (99.1 %), but the average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between strains G9T, 7MK23T and the closely related Dyella species listed above were in the ranges of 77.5–83.8 % and 22.0–27.0 %, much lower than the species demarcation lines of 95.5 and 70 %, respectively. Phylogenomic analyses using UBCG and Phylophlan also supported that these two strains represent two novel species of Dyella . The major fatty acids of strain G9T were iso-C15 : 0, iso-C17 : 1  ω9c and iso-C17 : 0 while that of strain 7MK23T were iso-C15 : 0 and anteiso-C15 : 0. Ubiquinone-8 was the only respiratory quinone detected in both strains. The polar lipids of strain G9T consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, and several unknown phospholipids, aminophospholipids, aminolipids and lipid while strain 7MK23T contained phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmethylethanolamine and several unknown phospholipids and aminophospholipids. The DNA G+C contents of strains G9T and 7MK23T were 64.7 and 63.4 mol%, respectively. On the basis of 16S rRNA gene sequence phylogenetic and phylogenomic analyses as well as phenotypic data obtained, we propose that strains G9T and 7MK23T represent two novel species of the genus Dyella , for which the names Dyella telluris sp. nov. (type strain G9T=KACC 21725T=GDMCC 1.2132T) and Dyella acidiphila sp. nov. (type strain 7MK23T=KCTC 62739T=GDMCC 1.1446T) are proposed.