Micromonospora antibiotica sp. nov. and Micromonospora humidisoli sp. nov., two new actinobacterial species exhibiting antimicrobial potential

Abstract

Two novel actinobacterial strains, designated MMS20-R2-23T and MMS20-R2-29T, were isolated from riverside soil and subjected to taxonomic characterization. Both strains were Gram-stain-positive, aerobic, non-motile and filamentous, and formed orange to strong orange-brown coloured colonies, which later turned black. Both strains grew optimally at mesophilic temperatures, neutral to slightly alkaline pH and in the absence of NaCl. Analysis of 16S rRNA gene sequences indicated that the two novel strains fell into phylogenetic clusters belonging to the genus Micromonospora . Strains MMS20-R2-23T and MMS20-R2-29T showed the highest 16S rRNA gene sequence similarity to Micromonospora phytophila SG15T (99.3 %) and Micromonospora humida MMS20-R1-14T (99.4 %), respectively. Based on the comparative genome analysis, strain MMS20-R2-23T had the highest orthologous average nucleotide identity (orthoANI) value of 92.70 % with Micromonospora matsumotoense DSM 44100T, and MMS20-R2-29T shared 94.99 % with Micromonospora wenchangensis CCTCC AA 2012002T. Besides, the digital DNA–DNA hybridization (dDDH) values of MMS20-R2-23T and MMS20-R2-29T with the same species were 47.6 and 59.2% respectively, which were also highest among the compared species, thus confirming the separation of each strain at species level from related species. The orthoANI and dDDH values between MMS20-R2-23T and MMS20-R2-29T were 92.18 and 44.9% respectively. The genomes of strains MMS20-R2-23T and MMS20-R2-29T were estimated as 7.56 Mbp and 7.13 Mbp in size, and the DNA G+C contents were 72.5 and 72.9 mol%, respectively. The chemotaxonomic properties of both strains were consistent with those of the genus. The novel strains showed antimicrobial activity against a broad range of microbes, in particular Gram-positive bacteria and yeasts. It is evident that each of the isolated strains merits recognition as representing novel species of Micromonospora , for which the names Micromonospora antibiotica sp. nov. (type strain=MMS20-R2-23T=KCTC 49542T=JCM 34495T) and Micromonospora humidisoli sp. nov. (type strain=MMS20-R2-29T=KCTC 49543T=JCM 34496T) are proposed.

Taxonomic Positions and Secondary Metabolite-Biosynthetic Gene Clusters of Akazaoxime- and Levantilide-Producers

“…In this study, we classified Micromonospora sp. AKA109, a producer of akazaoxime and A-76356, to M. humidisoli [ 40 ]. In contrast, Micromonospora sp.…”

“…M. humidisoli is very recently proposed, and its type strain, MMS20-R2-29 T , was isolated from riverside soil. It is explained that its growth occurs in the presence of 0–2% NaCl, with optimal growth at 0% NaCl [ 40 ]. In contrast, strain AKA109 was isolated from deep sea water with a higher salt concentration.…”

Brevibacillus humidisoli sp. nov., a moderately thermoalkaliphilic and halotolerant species isolated from riverside soil

“…Generally, phenotypic comparison of Brevibacillus is not straightforward, as most strains show poor activities in biochemical and physiological tests [6,7]. Through a series of recent studies, riverside soil has been found to be a unique environment and also a rich source of microbial diversity [8][9][10]. In this study, a novel strain designated MMS20-4M-10-Y T was isolated from riverside soil.…”

“…Through a series of recent studies, riverside soil has been found to be a unique environment and also a rich source of microbial diversity [8–10]. In this study, a novel strain designated MMS20-4M-10-Y T was isolated from riverside soil.…”

Description of Microcella humidisoli sp. nov. and Microcella daejeonensis sp. nov., isolated from riverside soil, reclassification of Marinisubtilis pacificus as Microcella pacifica comb. nov., and emended description of the genus Microcella

“…Riverside soil environments harbour a great deal of prokaryotic diversity with various metabolic potential, from which we isolated and described a number of novel taxa in recent years [4][5][6][7][8][9][10]. In this study, a polyphasic taxonomic approach including phylogenetic, phenotypic and chemotaxonomic characterization was employed to describe two new species of Microcella isolated from riverside soil.…”