Saccharopolyspora cavernae sp. nov., a Novel Actinomycete Isolated from the Swallow Cave in Yunnan, Southwest China

The genus Saccharopolyspora comprises 23 recognized species. Most species of the genus were isolated from soil samples. The genus encompasses aerobic, Gram-positive, non-acid-fast organisms which form extensively branched substrate mycelium that may fragment rod-shaped elements, and aerial mycelium that may form into bead-like chains of spores. Members of this genus are characterized chemotaxonomically by cell wall chemotype IV with eso-diaminopimelic acid, arabinose and galactose, with iso-branched and anteiso-branched fatty acids, lack of mycolic acids and MK-9(H₄) as the predominant menaquinone. The DNA G+C content is 66–77 mol%.

In this study, a Gram-positive, aerobic, non-motile actinobacterial strain, designated YIM C01235^T, was isolated from a soil sample collected from the Swallow Cave, Yunnan province, southwest China. The isolate grew at 10–30 °C, pH 6.0–9.0 and 0–8 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed highest similarity to Saccharopolyspora gloriosae YIM 60513^T (96.8 %), and lower 16S rRNA gene sequence similarities (95.1–96.7 %) with the other species of the genus Saccharopolyspora. The whole-cell hydrolysates contained meso-diaminopimelic acid (meso-DAP), arabinose and galactose. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylmethylethanolamine, two unknown glycolipids, two unknown phospholipids and one polar lipid. MK-9(H₄) was the predominant menaquinone. The major fatty acids were iso-C_15:0, iso-C_16:0, anteiso-C_15:0 and anteiso-C_17:0. Mycolic acids were not detected. The genomic DNA G+C content was 69.1 mol%.

These chemotaxonomic data, together with its morphological properties, were consistent with the assignment of strain YIM C01235^T to the genus Saccharopolyspora. The results of physiological and biochemical tests allowed strain YIM C01235^T to be differentiated phenotypically from all the recognized Saccharopolyspora species. On the basis of evidence from this polyphasic study, the novel species Saccharopolyspora cavernae sp. nov. is proposed. The type strain is YIM C01235^T (=DSM 45825^T = CCTCC AA 2012022^T). The result was published in Antonie van Leeuwenhoek in November 2013.