sp. nov., an endophytic actinomycete isolated from a promising candidate for biological pathogen control.

UNLABELLED

(E. Perrier) is an annelid of the genus in the family Megascolecidae, a species of earthworm, whose dried body (Guang Dilong) is a traditional Chinese animal medicine. A new actinobacterium strain, named HD1123-B1, was isolated from the gut contents of caught in the wild in Guangzhou, China. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strain was primarily identified as a member of the genus , sharing more than 98% sequence identity to CA3R110 (98.80%), CA1R205 (98.47%), and HM35 (97.93%). The whole genome size of strain HD1123-B1 was approximately 8.9 Mbp, with 7,464 predicted genes and 71.42 mol% DNA C+G content. Comparative genomic analyses based on digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values revealed that strain HD1123-B1 represents a novel species within the genus . Additionally, 38 biosynthetic gene clusters for secondary metabolites were also predicted in the genome of strain HD1123-B1. Based on LC-MS/MS analysis, the nigericin biosynthesis gene cluster has been completely characterized. The ethyl acetate crude extract of strain HD1123-B1 exhibited remarkable antibacterial activity against gram-positive bacteria (methicillin-resistant ATCC 25213, etc) and gram-negative bacteria GIM 1.70. Based on these results, HD1123-B1 could be confirmed as an isolate that represents a novel species of the genus , for which the name sp. nov. is proposed.

IMPORTANCE

As the largest genus of the phylum Actinomycetes, is a kind of microbial resources with great practical and economic value. Due to their unique physiological properties and metabolic capacity, have become an important source of bioactive compounds in the world and play an indispensable role in medical and industrial fields. With the advancement of molecular biology and genomics, researchers can more deeply explore the metabolic potential of Actinomycetes, discovering and developing new biologically active compounds. These new compounds may possess various biological activities, such as antibacterial, antiviral, antifungal, and antiparasitic properties, further promoting the development of medicine and related industries. Based on genomic analysis and antibacterial activity, the strain HD1123-B1 was indicated to be a promising candidate for biological pathogen control.