Asanoa endophytica sp. nov., an endophytic actinomycete isolated from the rhizome of Boesenbergia rotunda

A novel Gram-stain-positive, non-motile, endophytic actinomycete, designated strain BR3-1^T, which produced spore chains borne on the tips of short sporophores, was isolated from the rhizome of Boesenbergia rotunda collected from Udon Thani province, Thailand. This strain was investigated for its taxonomic position using a polyphasic approach. The strain contained 3-hydroxydiaminopimelic acid and meso-diaminopimelic acid in the cell-wall peptidoglycan. The whole-cell sugars comprised glucose, mannose, rhamnose, ribose and xylose. Phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannosides were found as the characteristic phospholipids. The predominant menaquinones were MK-10(H₈) and MK-10(H₆). The major cellular fatty acids were iso-C_16 : 0, iso-C_15 : 0 and anteiso-C_15 : 0. The G+C content of the genomic DNA was 71.4 mol%. 16S rRNA gene sequence analysis revealed that strain BR3-1^T belonged to the genus Asanoa and was most closely related to Asanoa ishikariensis (99.39 %), Asanoa iriomotensis (99.31 %), Asanoa siamensis (99.17 %), Asanoa ferruginea (98.84 %) and Asanoa hainanensis (98.71 %). The DNA-DNA relatedness value between strain BR3-1^T and its phylogenetically closest relatives was in the range of 15.4 % ± 1.2 to 45.8 % ± 2.6. In addition, some physiological and biochemical properties indicated that strain BR3-1^T could be readily distinguished from all type strains in the genus Asanoa. Thus, strain BR3-1^T should be classified as a representative of a novel species, for which the name Asanoa endophytica sp. nov. is proposed. The type strain is BR3-1^T ( = BCC 66355^T = NBRC 110002^T).

Mangrove rare actinobacteria: taxonomy, natural compound, and discovery of bioactivity

Actinobacteria are one of the most important and efficient groups of natural metabolite producers. The genus Streptomyces have been recognized as prolific producers of useful natural compounds as they produced more than half of the naturally-occurring antibiotics isolated to-date and continue as the primary source of new bioactive compounds. Lately, Streptomyces groups isolated from different environments produced the same types of compound, possibly due to frequent genetic exchanges between species. As a result, there is a dramatic increase in demand to look for new compounds which have pharmacological properties from another group of Actinobacteria, known as rare actinobacteria; which is isolated from special environments such as mangrove. Recently, mangrove ecosystem is becoming a hot spot for studies of bioactivities and the discovery of natural products. Many novel compounds discovered from the novel rare actinobacteria have been proven as potential new drugs in medical and pharmaceutical industries such as antibiotics, antimicrobials, antibacterials, anticancer, and antifungals. This review article highlights the latest studies on the discovery of natural compounds from the novel mangrove rare actinobacteria and provides insight on the impact of these findings.

Asanoa siamensis sp. nov., isolated from soil from a temperate peat swamp forest

A novel actinomycete strain, PS7-2T, which produced spore chains borne on the tips of short sporophores, was isolated from soil collected from a temperate peat swamp forest in Phu-Sang National Park, Phayao province, Thailand. The isolate contained glutamic acid, glycine, alanine, 3-hydroxy-diaminopimelic acid and meso-diaminopimelic acid in the cell-wall peptidoglycan. The whole-cell sugars were glucose, mannose, rhamnose and xylose, and the major phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and phosphatidylethanolamine. The predominant menaquinones were MK-10(H8) and MK-9(H8) and the predominant cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. The G+C content of the genomic DNA was 72.3 mol%. On the basis of 16S rRNA gene sequence analysis, strain PS7-2T clustered with members of the genus Asanoa and appeared most closely related to the type strains of Asanoa hainanensis (99.5 % sequence similarity), Asanoa iriomotensis (99.0 %), Asanoa ishikariensis (98.9 %) and Asanoa ferruginea (98.5 %). DNA–DNA hybridizations and some physiological and biochemical properties indicated that strain PS7-2T could be readily distinguished from its closest phylogenetic relatives. Based on the phenotypic and genotypic evidence and DNA–DNA relatedness values, strain PS7-2T represents a novel species in the genus Asanoa , for which the name Asanoa siamensis sp. nov. is proposed; the type strain is PS7-2T ( = BCC 41921T = NBRC 107932T).