Alterations in the Spectrum of Spontaneous Rifampicin-Resistance Mutations in the Bacillus subtilis rpoB Gene after Cultivation in the Human Spaceflight Environment

Abstract

The effect of Bacillus subtilis exposure to the human spaceflight environment on growth, mutagenic frequency, and spectrum of mutations to rifampicin resistance (RifR) was investigated. B. subtilis cells were cultivated in Biological Research in Canister-Petri Dish Fixation Units (BRIC-PDFUs) on two separate missions to the International Space Station (ISS), dubbed BRIC-18 and BRIC-21, with matching asynchronous ground controls. No statistically significant difference in either growth or in the frequency of mutation to RifR was found in either experiment. However, nucleotide sequencing of the RifR regions of the rpoB gene from RifR mutants revealed dramatic differences in the spectrum of mutations between flight (FL) and ground control (GC) samples, including two newly discovered rpoB alleles in the FL samples (Q137R and L489S). The results strengthen the idea that exposure to the human spaceflight environment causes unique stresses on bacteria, leading to alterations in their mutagenic potential.

Increased growth rate and amikacin resistance of Salmonella enteritidis after one‐month spaceflight on China’s Shenzhou‐11 spacecraft

“…A majority of studies revealed that the microgravity environment increased the growth rate of microbes (Benoit & Klaus, 2007;Kim et al, 2013;Vukanti, Model, & Leff, 2012). However, some studies showed that no difference was found in the growth rate between space flight and ground control cultures (Coil et al, 2016;Fajardo-Cavazos, Leehan, & Nicholson, 2018). Moreover, a few studies indicated that the flight strain performed significantly decelerated growth compared with the ground control experiment (Fajardo-Cavazos & Nicholson, 2016).…”

Meta-analysis of data from spaceflight transcriptome experiments does not support the idea of a common bacterial “spaceflight response”

“…For this study, we investigated transcriptomes from bacterial cultures grown in the human spaceflight environment and their corresponding ground control cultures. Spaceflight experiments and organisms included: MESSAGE 2 and BASE A ( Rhodospirillum rubrum strain S1H) 11 ; STS-115 ( Salmonella enterica serovar Typhimurium strain χ3339 and Pseudomonas aeruginosa strain PAO1) 8 , 9 ; STS-123 ( S. enterica serovar Typhimurium strain χ3339) 10 ; BRIC-21 ( Bacillus subtilis strain 168) 22 , 23 ; and BRIC-23 ( B. subtilis strain 168 and Staphylococcus aureus strain UAMS-1) 15 . All of the datasets used are openly available through NASA’s GeneLab Data System (GLDS) repository (genelab.nasa.gov) and are listed in Table 1 .…”

Decreased biofilm formation ability of Acinetobacter baumannii after spaceflight on China's Shenzhou 11 spacecraft

“…Bacillus cereus was reportedly altered (Fajardo-Cavazos, 2018;Fajardo-Cavazos & Nicholson, 2016;Guo et al, 2014;Su et al, 2014), and drug resistance persisted in K. pneumoniae and B. subtilis cultured in a spacecraft or in the ISS (Guo et al, 2015;Morrison et al, 2017). Previous studies have reported an increased incidence of mutations in bacteria after spaceflight (Sulzman & Genin, 1994).…”

“…Escherichia coli and B. subtilis cultured in space shuttle mission STS‐63 displayed a greater density of cells in the stationary phase, with a shorter lag‐phase (Kacena, Merrell, et al, ). Drug resistance of Staphylococcus epidermidis , Klebsiella pneumoniae , and Bacillus cereus was reportedly altered (Fajardo‐Cavazos, ; Fajardo‐Cavazos & Nicholson, ; Guo et al, ; Su et al, ), and drug resistance persisted in K. pneumoniae and B. subtilis cultured in a spacecraft or in the ISS (Guo et al, ; Morrison et al, ). Previous studies have reported an increased incidence of mutations in bacteria after spaceflight (Sulzman & Genin, ).…”