AUTHOR=Mohammadi Barakatullah , Gorkina Natalia , Pérez-Reyes Marco Esteban , Smith Stephanie A. 

TITLE=Profiling toxin genes and antibiotic resistance in Bacillus cereus isolated from pre-launch spacecraft

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1231726

DOI=10.3389/fmicb.2023.1231726

ISSN=1664-302X

ABSTRACT=<p>Characterization of the microbiomes of pre-launch spacecraft in spacecraft assembly facilities is an important step in keeping crews healthy during journeys that can last several hundred days in small artificial environments in space. <italic>Bacillus cereus</italic>, a foodborne pathogenic bacterium, has the potential to be a significant source of food contamination in such environments. This bacterium is a spore-forming bacteria that resists different antimicrobial treatments in cleanrooms where spacecraft are assembled. This study evaluated 41 <italic>B. cereus</italic> isolates from four pre-launch spacecraft in spacecraft assembly facilities for their toxin gene profile and antibiotic resistance. Four enterotoxin genes (<italic>hlbC</italic>, <italic>cytK</italic>, <italic>nheA</italic>, and <italic>entFM</italic>) and two emetic toxin genes (<italic>ces</italic> and <italic>CER</italic>) were targeted for chromosomal DNA and plasmid DNA. Results showed 31.7, 7.3, 85, and 41.5% of isolates contained <italic>hblC</italic>, <italic>cytK</italic>, <italic>nheA</italic>, and <italic>entFM</italic>, respectively, in chromosomal or plasmid DNA. Overall, 37 isolates (90.2%) showed at least one enterotoxin gene. The emetic toxin gene, <italic>ces</italic>, was detected in the plasmid DNA of three isolates (7.3%). The antibiotic resistance of isolates was evaluated by the Kirby-Bauer disk diffusion procedure. All the isolates exhibited 100% susceptibility to gentamicin, 97% were susceptible to clindamycin, and 95% to chloramphenicol, imipenem, tetracycline, and vancomycin. The overall susceptibility average is 51%. However, 98% of the isolates were resistant to β-lactam antibiotics, 97.5% were resistant to sulfamethoxazole/trimethoprim, and 80% were resistant to rifampin. This study provides important information on <italic>B. cereus</italic> isolates from spacecraft assembly facilities for use in microbial monitoring programs of spacecraft.</p>