Genomic description of sp. nov., a bacterium collected from the International Space Station that exhibits unique antimicrobial-resistant and virulent phenotype.

UNLABELLED

A novel bacterial strain, designated as 1F8SW-P5, was isolated from the wall of the crew quarters on the International Space Station. Cells were Gram-staining-positive, strictly aerobic, non-spore-forming, chemoheterotrophic, and mesophilic rods exhibiting catalase-positive and oxidase-negative reactivity. Strain 1F8SW-P5 shared the highest 16S rRNA gene similarity with CECT 8356 (99.34%) and the highest gene similarity with KSW2-21 (91.34%). Its strongest matches via average nucleotide identity and DNA-DNA hybridization were to CGMCC_1.12512 (84.36% and 25.80%, respectively). 1F8SW-P5 formed a distinct lineage during phylogenetic and phylogenomic analysis. The biochemical, phenotypic, chemotaxonomic, and phylogenomic features substantiated the affiliation to 1F8SW-P5 as a new species of , for which we propose the name , with the type strain 1F8SW-P5 (=DSM 115934 =NRRL B-65667). Based on metagenomic data collected during the Microbial Tracking mission series, was identified from all surfaces ( = 8) over an 8-year period, with an increase in relative abundance over time. This is of potential concern, as we observed resistance to all tested fluoroquinolone antibiotics ( = 6), two β-lactam antibiotics, and one macrolide antibiotic, which was not predicted based on isolate or plasmid genotype alone. Furthermore, we found an increase in virulence, compared to , when tested within a model. This pathogenic profile highlights the importance of continued characterization of spacecraft-associated microbes, the characterization of previously unidentified antimicrobial resistance and virulence genes, and the implementation of targeted mitigation strategies during spaceflight.

IMPORTANCE

Crew members are at an increased risk for exposure to and infection by pathogenic microbes during spaceflight. Therefore, it is imperative to characterize the species that are able to colonize and persist on spacecraft, how those organisms change in abundance and distribution over time, and their genotypic potential for and phenotypic expression of pathogenic traits (i.e., whether they encode for or exhibit traits associated with antibiotic resistance and/or virulence). Here, we describe a novel species of collected from the crew quarters on the International Space Station (ISS), 1F8SW-P5, for which we propose the name . was found to be distributed throughout the ISS with an increase in relative abundance over time. Additionally, this bacterium exhibits a unique antibiotic resistance phenotype that was not predicted from whole-genome sequencing, as well as increased virulence, suggesting the need for the identification of previously undescribed antimicrobial resistance genes and monitoring/mitigation during spaceflight.