AUTHOR=Kaewkla Onuma , Perkins Mike , Thamchaipenet Arinthip , Saijuntha Weerachai , Sukpanoa Sudarat , Suriyachadkun Chanwit , Chamroensaksri Nitcha , Chumroenphat Theeraphan , Franco Christopher Milton Mathew 

TITLE=Description of Streptomyces naphthomycinicus sp. nov., an endophytic actinobacterium producing naphthomycin A and its genome insight for discovering bioactive compounds

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1353511

DOI=10.3389/fmicb.2024.1353511

ISSN=1664-302X

ABSTRACT=<p>Endophytic actinobacteria are a group of bacteria living inside plant tissue without harmful effects, and benefit the host plant. Many can inhibit plant pathogens and promote plant growth. This study aimed to identify a strain of <italic>Streptomyces</italic> as a novel species and study its antibiotics production. An endophytic actinobacterium, strain TML10<sup>T</sup> was isolated from a surface-sterilized leaf of a Thai medicinal plant (<italic>Terminalia mucronata</italic> Craib and Hutch). As a result of a polyphasic taxonomy study, strain TML10<sup>T</sup> was identified as a member of the genus <italic>Streptomyces</italic>. Strain TML10<sup>T</sup> was an aerobic actinobacterium with well-developed substrate mycelia with loop spore chains and spiny surface. Chemotaxonomic data, including cell wall components, major menaquinones, and major fatty acids, confirmed the affiliation of strain TML10<sup>T</sup> to the genus <italic>Streptomyces</italic>. The results of the phylogenetic analysis, including physiological and biochemical studies in combination with a genome comparison study, allowed the genotypic and phenotypic differentiation of strain TML10<sup>T</sup> and the closest related type strains. The digital DNA-DNA hybridization (dDDH), Average nucleotide identity Blast (ANIb), and ANIMummer (ANIm) values between strain TML10<sup>T</sup> and the closest type strain, <italic>Streptomyces musisoli</italic> CH5-8<sup>T</sup> were 38.8%, 88.5%, and 90.8%, respectively. The name proposed for the new species is <italic>Streptomyces naphthomycinicus</italic> sp. nov. (TML10<sup>T</sup> = TBRC 15050<sup>T</sup> = NRRL B-65638<sup>T</sup>). Strain TML10<sup>T</sup> was further studied for liquid and solid-state fermentation of antibiotic production. Solid-state fermentation with cooked rice provided the best conditions for antibiotic production against methicillin-resistant <italic>Staphylococcus aureus</italic>. The elucidation of the chemical structures from this strain revealed a known antimicrobial agent, naphthomycin A. Mining the genome data of strain TML10<sup>T</sup> suggested its potential as a producer of antbiotics and other valuable compounds such as ε-Poly-L-lysine (ε-PL) and arginine deiminase. Strain TML10<sup>T</sup> contains the <italic>arc</italic>A gene encoding arginine deiminase and could degrade arginine <italic>in vitro</italic>.</p>