AUTHOR=Králová Stanislava , Sandoval-Powers Megan , Fawwal Dorelle V. , Degnes Kristin F. , Lewin Anna Sofia , Klinkenberg Geir , Nguyen Giang-Son , Liles Mark R. , Wentzel Alexander 

TITLE=Streptomyces tardus sp. nov.: A Slow-Growing Actinobacterium Producing Candicidin, Isolated From Sediments of the Trondheim Fjord

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.714233

DOI=10.3389/fmicb.2021.714233

ISSN=1664-302X

ABSTRACT=<p>Marine environments are home to an extensive number of microorganisms, many of which remain unexplored for taxonomic novelty and functional capabilities. In this study, a slow-growing <italic>Streptomyces</italic> strain expressing unique genomic and phenotypic characteristics, P38-E01<sup><italic>T</italic></sup>, was described using a polyphasic taxonomic approach. This strain is part of a collection of over 8,000 marine Actinobacteria isolates collected in the Trondheim fjord of Norway by SINTEF Industry (Trondheim, Norway) and the Norwegian University of Science and Technology (NTNU, Trondheim, Norway). Strain P38-E01<sup><italic>T</italic></sup> was isolated from the sediments of the Trondheim fjord, and phylogenetic analyses affiliated this strain with the genus <italic>Streptomyces</italic>, but it was not closely affiliated with other described species. The closest related type strains were <italic>Streptomyces daliensis</italic> YIM 31724<sup><italic>T</italic></sup> (98.6%), <italic>Streptomyces rimosus</italic> subsp. <italic>rimosus</italic> ATCC 10970<sup><italic>T</italic></sup> (98.4%), and <italic>Streptomyces sclerotialus</italic> NRRL ISP-5269<sup><italic>T</italic></sup> (98.3%). Predominant fatty acids were C<sub>16:0</sub> iso, C<sub>16:0</sub>, and Summed Feature 3, and the predominant respiratory quinones were MK-10(H<sub>6</sub>), MK-10(H<sub>4</sub>), and MK9(H<sub>4</sub>). The main polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, and phosphoglycolipid. The whole-cell sugars were glucose, ribose, and in minor amounts, mannose. The cell wall peptidoglycan contained LL-diaminopimelic acid. The draft genome has a size of 6.16 Mb, with a %G + C content of 71.4% and is predicted to contain at least 19 biosynthetic gene clusters encoding diverse secondary metabolites. Strain P38-E01<sup><italic>T</italic></sup> was found to inhibit the growth of the pathogenic yeast <italic>Candida albicans</italic> ATCC 90028 and a number of Gram-positive bacterial human and plant pathogens. Metabolites extracted from cultures of P38-E01<sup><italic>T</italic></sup> were analyzed by mass spectrometry, and it was found that the isolate produced the antifungal compound candicidin. Phenotypic and chemotaxonomic signatures, along with phylogenetic analyses, distinguished isolate P38-E01<sup><italic>T</italic></sup> from its closest neighbors; thus, this isolate represents a novel species of the genus <italic>Streptomyces</italic> for which the name <italic>Streptomyces tardus</italic> sp. nov. (P38-E01<sup><italic>T</italic></sup> = CCM 9049<sup><italic>T</italic></sup> = DSM 111582<sup><italic>T</italic></sup>) is proposed.</p>