Unusual Genomic and Biochemical Features of Paenarthrobacter lasiusi sp. nov—A Novel Bacterial Species Isolated from Lasius niger Anthill Soil

The black garden ant (<i>Lasius niger</i>) is a widely distributed species across Europe, North America, and North Africa, playing a pivotal role in ecological processes within its diverse habitats. However, the microbiome associated with <i>L. niger</i> remains poorly investigated. In the present study, we isolated a novel species, <i>Paenarthrobacter lasiusi</i>, from the soil of the <i>L. niger</i> anthill. The genome of <i>P. lasiusi</i> S21 was sequenced, annotated, and searched for groups of genes of physiological, medical, and biotechnological importance. Subsequently, a series of microbiological, physiological, and biochemical experiments were conducted to characterize <i>P. lasiusi</i> S21 with respect to its sugar metabolism, antibiotic resistance profile, lipidome, and capacity for atmospheric nitrogen fixation, among others. A notable feature of the <i>P. lasiusi</i> S21 genome is the presence of two prophages, which may have horizontally transferred host genes involved in stress responses. <i>P. lasiusi</i> S21 synthesizes a number of lipids, including mono- and digalactosyldiacylglycerol, as well as steroid compounds that are typically found in eukaryotic organisms rather than prokaryotes. <i>P. lasiusi</i> S21 exhibits resistance to penicillins, lincosamides, fusidins, and oxazolidinones, despite the absence of specific genes conferring resistance to these antibiotics. Genomic data and physiological tests indicate that <i>P. lasiusi</i> S21 is nonpathogenic to humans. The genome of <i>P. lasiusi</i> S21 contains multiple operons involved in heavy metal metabolism and organic compound inactivation. Consequently, <i>P. lasiusi</i> represents a novel species with an intriguing evolutionary history, manifesting in distinctive genomic, metabolomic, and physiological characteristics. This species may have potential applications in the bioaugmentation of contaminated soils.