Fictibacillus tiangongensis sp. nov., isolated from the China Space Station.

The identification of novel microbial species in extreme environments significantly enhances our comprehension of Earth's biodiversity and concurrently offers invaluable resources and critical insights for scientific research, biotechnological innovation and environmental conservation. As part of the China Space Station Habitation Area Microbiome Program (CHAMP), a Gram-positive, facultatively anaerobic, motile, spore-forming, rod-shaped strain, designated JL2B1089T, was isolated from the surface of hardware within the genus Fictibacillus. The strain grows optimally at 30-37 °C and pH 7-8 with 0-2.0% (w/v) NaCl. Phylogenetic analyses based on the genomic data revealed that JL2B1089T is closely related to Fictibacillus phosphorivorans Ca7T, with average nucleotide identity and digital DNA-DNA hybridization values of 90.0 and 40.6%, respectively; both values are below the recommended thresholds for species delineation. Chemotaxonomic characteristics, including the major cellular fatty acids iso-C15:0 and anteiso-C15:0, the predominant menaquinone-7 and a cell-wall peptidoglycan containing meso-diaminopimelic acid, are consistent with those of the closely related taxa F. phosphorivorans Ca7T and Fictibacillus halophilus AS8T. Additionally, strain JL2B1089T shows specificity in utilizing certain substrates, such as amino acids and carboxylic acids. Pan-genome analysis and divergence analysis of the bacillithiol biosynthesis deacetylase (BshB1) protein suggest that this strain may adapt to the space environment through mechanisms involved in coping with cell morphological alterations, osmotic fluctuations and oxidative damage under microgravity conditions. Based on phenotypic, chemotaxonomic and genomic characteristics, strain JL2B1089T represents a novel species within the genus Fictibacillus, for which the name Fictibacillus tiangongensis sp. nov. is proposed. The type strain is JL2B1089T (=GDMCC 1.4870T=KCTC 43746T).