Abstract
Two novel actinomycetal strains, designated CC-R113(T) and CC-R104(T), were isolated from the tissues of two macroalgae collected on the northern Portuguese coast. Phylogenetic analyses based on the 16S rRNA gene showed that strain CT-R113(T) belongs to the genus Nocardiopsis, being closely related to Nocardiopsis umidischolae 66/93(T) and Nocardiopsis tropica VKM Ac-1457(T), with 98.65 and 98.39 % sequence similarity, respectively. The clade formed between the three type strains was confirmed by phylogenomic analysis. The genome of strain CT-R113(T) was 7.27 Mb in size with a G+C content of 71.3 mol %, with average nucleotide identity (ANI) values of 89.59 and 90.14 % with strains 66/93(T) and VKM Ac-1457(T), respectively. The major cellular fatty acids were identified as C(18 : 1) ω9c, iso-C(16 : 0) and anteiso-C(17 : 0). Menaquinone 10 (MK-10) was the major respiratory quinone. Comparative analysis of 16S rRNA gene sequences showed that strain CC-R104(T) belongs to the genus Rhodococcus and is most closely related to Rhodococcus pyridinivorans DSM 44555(T), with 98.24 % sequence similarity. However, phylogenomic analysis revealed that strain CC-R104(T) establishes a clade with Rhodococcus artemisae DSM 45380(T), being more distant from Rhodococcus pyridinivorans DSM 44555(T). The genome of strain CC-R104(T) was 5.34 Mb in size with a G+C content of 67.01 mol%. The ANI value between strains CC-R104(T) and DSM 45380(T) was 81.2 % and between strains CC-R104(T) and DSM 44555(T) was 81.5 %. The major cellular fatty acids were identified as C(18 : 1) ω9c, C(16 : 0) and summed feature 3. Menaquinone 8 (MK-8) was the only respiratory quinone. For both CC-R113(T) and CC-R104(T), optimum growth was observed at pH 7.0, 28 °C and 0-5 % NaCl and whole-cell hydrolysates contained meso-diaminopimelic acid as the cell-wall diamino acid. On the basis of phenotypic, molecular and chemotaxonomic characteristics, strains CT-R113(T) and CC-R104(T) are considered to represent novel species, for which the names Nocardiopsis codii sp. nov. (type strain CT-R113(T)=LMG33234(T)=UCCCB172(T)) and Rhodococcus chondri sp. nov. (type strain CC-R104(T)=LMG33233(T)=UCCCB171(T)) are proposed.