Bacteria of the genus Bacillus on the Russian segment of the International Space Station

Pure cultures of 19 strains of spore-forming bacteria were obtained from the equipment surfaces of the Russian segment of the International Space Station. The study of morphological, cultural and physiological-biochemical properties of these bacteria allowed us to attribute all strains to the genus Bacillus. As a result of using MALDI-TOF methods and genome-wide sequencing, it was found that out of 19 bacillus strains, six belong to the species B. paralicheniformis, four to B. pumilus, four to B. subtilis, two to B. cereus and one to B. amyloliquefaciens. In accordance with the requirements and norms of EUCAST 2023, the resistance of bacillus strains obtained from the Russian segment of the International Space Station to antibiotics such as imipenem, meropenem, ciprofloxacin, levofloxacin, norfloxacin, vancomycin, erythromycin, clindamycin and linezolid was studied. Resistance to erythromycin was found in 11 strains of bacilli and five strains showed resistance to clindamycin. Only one strain showed resistance to imipenem, levofloxacin and norfloxacin, respectively. Analysis of the complete genome of bacterial strains in which resistance to erythromycin and (or) clindamycin was found made it possible to establish that resistance to these antibiotics in B. paralicheniformis strains SE71, SE131, SE181, SE182, SE183 provides the ermD antibiotic resistance gene. In B. cereus SE43, resistance to erythromycin encodes the mphL gene.