Actinomadura syzygii sp. nov., an endophytic actinomycete isolated from the roots of a jambolan plum tree (Syzygium cumini L. Skeels)

Abstract

The taxonomic position of an endophytic actinomycete, strain GKU 157T, isolated from the roots of a jambolan plum tree (Syzygium cumini L. Skeels) collected at Khao Khitchakut National Park, Chantaburi province, Thailand, was determined using a polyphasic taxonomic approach. 16S rRNA gene sequence analysis revealed that strain GKU 157T belongs to the genus Actinomadura and formed a distinct phyletic line with Actinomadura chibensis NBRC 106107T (98.6 % similarity). Strain GKU 157T formed an extensively branched, non-fragmenting substrate mycelium and aerial hyphae that differentiated into hooked to short spiral chains of about 20 non-motile spores with a warty surface. The cell wall contained meso-diaminopimelic acid and the whole-cell sugars were galactose, glucose, madurose, mannose and ribose. The N-acyl type of muramic acid was acetyl. Mycolic acids were absent. The phospholipids included phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), phosphatidylinositol (PI), phosphatidylinositolmannoside (PIM) and two unknown phospholipids (PLs). The major menaquinone was MK-9(H6) and the predominant fatty acids were C16:0, iso-C16:0, C18:1ω9c, C18:0 and 10-methyl C18:0 (tuberculostearic acid). The genomic DNA G+C content was 73.1 mol%. A combination of DNA–DNA hybridization results and significant differences from related species in cultural, physiological and chemical characteristics indicated that strain GKU 157T represents a novel species of the genus Actinomadura, for which the name Actinomadura syzygii sp. nov. is proposed. The type strain is GKU 157T ( = BCC 70456T = NBRC 110399T).