ABSTRACT
A synopsis of Heliotropiaceae in Thailand is presented and, as part of this, the taxonomic history, identification keys, distribution maps, herbarium specimen citations and diagnostic characters are provided. Two genera and 12 species are recognised and four new combinations are proposed of Tournefortia under the genus Heliotropium, namely H.hookeri, H.intonsum, H.montanum and H.ovatum. Two species are newly recorded in Thailand: Euplocaovalifolia and H.hookeri. The neotype and lectotype are designated here for Tournefortiamontana and T.boniana, respectively.
ABSTRACT
Two endophytic actinobacteria, designated as strains 7R015T and 7R016T, were isolated from the roots of Barleria lupulina collected in Thailand. The morphological characteristics and results of chemotaxonomic studies and 16S rRNA gene analysis indicated that both strains represented members of the genus Streptomyces. They contained ll-diaminopimelic acid in the peptidoglycan. Ribose and glucose were detected as the whole-cell sugars. MK-9(H4), MK-9(H6) and MK-9(H8), were found as the membrane menaquinone. The predominant cellular fatty acids detected were iso-C16â:â0 and anteiso-C15â:â0. The genomes of both strains harboured biosynthetic gene clusters for melanin, terpene, lanthipeptide, polyketides, non-ribosomal peptide synthetase, siderophore and ectoine. The 16S rRNA gene sequence of 7R015T showed the highest similarity to that of Streptomyces pseudovenezuelae DSM 40212T (98.6â%), Streptomyces cyaneus NRRL B2296T (98.6â%) and Streptomyces curacoi DSM 40107T (98.6â%). Strain 7R016T showed the highest 16S rRNA gene sequence similarity to Streptomyces gilvifuscus NBRC 110904T (98.2â%), which is lower than the threshold value for 16S rRNA gene sequence similarity for differentiation at the species level (98.65â%). Comparative genome analysis revealed that the genomes of 7R015T, 7R016T and the closely related type strains had an average nucleotide identity (ANI) of less than 95â% and a digital DNA-DNA hybridisation (dDDH) of less than 70â%, the thresholds for species demarcation. On the basis of the results of the polyphasic study, strains 7R015T and 7R016T represent novel species of the genus Streptomyces and are named herein as Streptomyces cylindrosporus sp. nov. (=NBRC 115200T = TBRC 14542T) for strain 7R015T and Streptomyces spinosisporus sp. nov. (=NBRC 115201T = TBRC 14543T) for strain 7R016T.
Subject(s)
Acanthaceae , Actinobacteria , Streptomyces , Fatty Acids/chemistry , Phospholipids/analysis , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Phylogeny , Base Composition , DNA, Bacterial/genetics , Bacterial Typing TechniquesABSTRACT
Endophytic actinobacterial strain 3R004T was isolated from a root of Justicia subcoriacea collected in Thailand. In this report, the taxonomic position of this strain is described using a polyphasic approach. Based on the morphological characteristics and chemical composition of its cells, strain 3R004T was identified as a member of the genus Streptomyces. It produced a long chain of cylindrical spores on aerial mycelia. ll-Diaminopimelic acid was detected in the cell wall peptidoglycan. The menaquinones were MK-9(H4), MK-9(H6) and MK-9(H8). C16â:â0, iso-C16â:â0, anteiso-C15â:â0 and iso-C15â:â0 were detected as the major cellular fatty acids. Polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and one unidentified lipid. Strain 3R004T showed the highest 16S rRNA gene similarity of 99.45â% to Streptomyces cyaneochromogenes MK-45T. The phylogenomic results indicated that strain 3R004T was close to Streptomyces aquilus GGCR-6T and Streptomyces antibioticus DSM 40234T. The DNA-DNA hybridization and average nucleotide identity values among strain 3R004T and closely related Streptomyces species were 35.5-63.1â% and 82.7-94.3â%, respectively. The type strain produced actinomycin D antibiotic as the major secondary metabolite. The maximum productivity of the actinomycin D (378 mg l-1) was observed when the strain was grown in 301 broth at 30 °C, 180 r.p.m. for 12 days. On the basis of phenotypic and genotypic evidence, strain 3R004T represents a novel species of the genus Streptomyces, for which the name Streptomyces justiciae is proposed. The type strain is 3R004T (=LMG 32138T=TBRC 13128T=NBRC 115065T).
