Abstract
A novel actinomycete producing heliquinomycin and 9’-methoxy-heliquinomycin, designated strain jys28T, was isolated from rhizosphere soil of Pinus yunnanensis and characterized using a polyphasic approach. The strain had morphological characteristics and chemotaxonomic properties identical to those of members of the genus Streptomyces. It formed spiral chains of spores with spiny surfaces. The menaquinones detected were MK-9(H6), MK-9(H8) and MK-9(H4). The major fatty acids were iso-C16:0, C15:0, C16:1ω7с and anteiso-C15:0. The phospholipids were diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine and phosphatidylinositol mannoside. The DNA G + C content of the draft genome sequence, consisting of 8.5 Mbp, was 70.6%. Analysis of the 16S rRNA gene sequence showed that strain jys28T belongs to the genus Streptomyces with the highest sequence similarities to Streptomyces chattanoogensis NBRC 13058T (99.2%) and Streptomyces lydicus DSM 40002T (99.2%) and phylogenetically clustered with them. Multilocus sequence analysis based on five other house-keeping genes (atpD, gyrB, rpoB, recA and trpB) and the low level of DNA–DNA relatedness and phenotypic differences allowed the novel isolate to be differentiated from its most closely related strains. Therefore, the strain is concluded to represent a novel species of the genus Streptomyces, for which the name Streptomyces piniterrae sp. nov. is proposed. Furthermore, the putative biosynthetic gene cluster of heliquinomycins was identified and the biosynthetic pathway was discussed. The type strain is jys28T (=CCTCC AA 2018051T =DSM 109823T).
Highlights
Actinobacteria has been the most fruitful source of microorganisms for all types of bioactive metabolites, including antibiotics, immunosuppressive agents, antitumor agents, and enzymes [1]
During our continuous efforts to discover new or bioactive natural products from actinobacteria, we have reported the chemical studies of Streptomyces piniterrae jys28T isolated from rhizosphere soil of Pinus yunnanensis, and identified heliquinomycin and its new analogue, 9’-methoxy-heliquinomycin [3]
Identification using the EzTaxon-e server revealed that strain jys28T belonged to the genus Streptomyces with the highest 16S rRNA gene sequence similarities to S. chattanoogensis NBRC 13058T (99.2%) and S. lydicus DSM 40002T (99.2%). 16S rRNA gene sequence similarities between strain jys28T and other species of the genus Streptomyces were lower than 99.0%
Summary
Actinobacteria has been the most fruitful source of microorganisms for all types of bioactive metabolites, including antibiotics, immunosuppressive agents, antitumor agents, and enzymes [1]. Multiple structural types of antibiotics, including amino glycosides, chloramphenicol, tetracyclines, macrolides and β-lactams, have been isolated from cultures of this genus [2]. During our continuous efforts to discover new or bioactive natural products from actinobacteria, we have reported the chemical studies of Streptomyces piniterrae jys28T isolated from rhizosphere soil of Pinus yunnanensis, and identified heliquinomycin and its new analogue, 9’-methoxy-heliquinomycin [3]. Since the initial isolation and discovery of rubromycins in 1953 from Streptomyces collinus, more abundant compounds of rubromycin family, including purpuromycin, griseorhodins and heliquinomycins, have been identified by the end of the 20th century [4,5,6,7]. With the clear recognition of biosynthetic gene clusters of rubromycins, further studies of the individual enzymes are required to determine the exact biosynthetic pathway
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