Polyphasic taxonomic description of Micromonospora aquaegermanicae sp. nov. and Plantactinospora tunisiensis sp. nov.

Abstract Two actinobacterial strains, DSM 43699 T and JZT32 T , isolated from water and soil samples collected in Germany and Tunisia, respectively, were investigated using comprehensive polyphasic taxonomic studies. The morphological and phenotypic features of the strains were consistent with those of members of the genera Micromonospora and Plantactinospora . Strain DSM 43699ᵀ exhibited highest 16S rRNA gene sequence similarity (99.2%) to Micromonospora rifamycinica AM105ᵀ, whereas strain JZT32ᵀ showed 98.6% similarity to Plantactinospora veratri NEAU-FHS4ᵀ. In contrast, phylogenomic analysis identified Micromonospora matsumotoensis DSM 44100ᵀ and Plantactinospora soli KLBMP 9567ᵀ as the close relatives of strains DSM 43699ᵀ and JZT32ᵀ, respectively. Digital DNA-DNA hybridisation (dDDH) and average nucleotide identity (ANI) values between the genomic sequences of strains DSM 43699 T and JZT32 T and their close phylogenomic neighbours were well below the thresholds of 70% (DDH) and 95–96% (ANI) for prokaryotic species demarcation. Based on the cumulative polyphasic evidence, strains DSM 43699 T (4/2/0.5/24 T = KCTC 59416 T ) and JZT32 T (DSM 117369 T = CECT 31214 T ) are proposed as type strains of two novel species, for which the names Micromonospora aquaegermanicae sp. nov. and Plantactinospora tunisiensis sp. nov. are proposed, respectively. Genome mining revealed diverse biosynthetic gene clusters, and antimicrobial bioassays demonstrated promising bioactive potential, indicating that both strains represent valuable sources of bioactive compounds.