A novel actinomycete strain PM05-2T was isolated from the lichen Parmotrema praesorediosum (Nyl.) Hale collected from Chaiyaphum Province, Thailand. The taxonomic position of the strain was studied using the polyphasic approach. Based on the morphology and chemotaxonomic properties, strain PM05-2T was identified as a member of the genus Actinomadura. The whole-cell hydrolysate contained meso-diaminopimelic acid, rhamnose, ribose, xylose, madurose, glucose and galactose. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, one unidentified phosphoglycolipid, four unidentified phospholipids and one unidentified lipid. The menaquinones were MK-9(H6), MK-9(H4), MK-9(H2), MK-9(H8) and MK-9(H0). The major cellular fatty acids were C16:0 and C18:1 ω9c. Strain PM05-2T showed the highest 16S rRNA gene similarity to Actinomadura hibisca NBRC 15177T (98.58%), Actinomadura kijaniata NBRC 14229T (98.29 %) and Actinomadura namibiensis DSM 44197T (98.14 %). The phylogenetic tree analysis revealed that strain PM05-2T was related to A. hibisca NBRC 15177T, A. kijaniata NBRC 14229T, A. namibiensis DSM 44197T and Actinomadura macrotermitis RB68T. The genomic analysis revealed that average nucleotide identity values based on both blast and MUMmer between strain PM05-2T and the relative type strains ranged from 77.6 to 86.4%. The digital DNA-DNA hybridization values among the strains were lower than the threshold for assigning to the same species. The taxonomic results suggested that strain PM05-2T represented a novel species of the genus Actinomadura for which the name Actinomadura parmotrematis is proposed. The type strain is PM05-2T (=TBRC 15492T=NBRC 115416T).
Keywords: Actinobacteria; Parmotrema; lichen; rare Actinobacteria.