Thermotunica guangxiensis gen. nov., sp. nov., isolated from mushroom residue compost

Abstract

A novel thermophilic actinomycete, designated AG2-7T, was isolated from mushroom residue compost in Guangxi University, Nanning, China. The strain grew optimally at 45–60 °C, at pH 7.0 and with 0–3.0 % (w/v) NaCl. Vegetative mycelia were branched and whitish to pale yellow without fragmentation. Aerial mycelium was abundant, whitish and differentiated into long chains of spores, with a membranous structure or tunica partially covering the surface of aerial hyphae. The non-motile spores were oval in shape with a ridged surface. Strain AG-27T contained meso-diaminopimelic acid as the diagnostic diamino acid, and the whole-cell sugars were galactose and ribose. Major fatty acids were iso-C16 : 0 (27.51 %), iso-C17 : 0 (10.47 %) and anteiso-C17 : 0 (12.01 %). MK-9(H4) was the predominant menaquinone. The polar phospholipids were diphosphatidylglycerol, ninhydrin-positive glycophospholipid, phosphatidylinositol, phosphatidylinositol mannoside, phosphatidylethanolamine, phosphatidylmethylethanolamine, an unknown phospholipid and unknown glucosamine-containing phospholipids. The G+C content of the genomic DNA was 63.6 mol%. 16S rRNA gene sequence analysis showed that the organism belonged to the family Pseudonocardiaceae , suborder Pseudonocardineae and showed more than 5 % divergence from other members of the family. Based on the phenotypic and phylogenetic data, strain AG2-7T represents a novel species of a new genus in the family Pseudonocardiaceae , for which the name Thermotunica guangxiensis gen. nov., sp. nov. is proposed. The type strain of the type species is AG2-7T ( = ATCC BAA-2499T = CGMCC 4.7099T).