Bacteria of the Genus Bacillus on the Russian Segment of the International Space Station

Abstract

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 the authors to attribute all strains to the genus Bacillus. As a result of using MALDI-TOF methods and genome-wide sequencing, it was found that six of 19 bacillus strains 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 such antibiotics as imipenem, meropenem, ciprofloxacin, levofloxacin, norfloxacin, vancomycin, erythromycin, clindamycin, and linezolid was studied. Resistance to erythromycin was found in 11 strains of Bacillus, 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, and SE183 provides the ermD antibiotic resistance gene. In B. cereus SE43, resistance to erythromycin encodes the mphL gene.