Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “antibiotic resistance”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Distribution of Antibiotic Resistance in a Mixed-Use Watershed and the Impact of Wastewater Treatment Plants on Antibiotic Resistance in Surface Water

The aquatic environment has been recognized as a source of antibiotic resistance (AR) that factors into the One Health approach to combat AR. To provide much needed data on AR in the environment, a comprehensive survey of antibiotic-resistant bacteria (ARB), antibiotic resistance genes (ARGs), and antibiotic residues was conducted in a mixed-use watershed and wastewater treatment plants (WWTPs) within the watershed to evaluate these contaminants in surface water. A culture-based approach was used to determine prevalence and diversity of ARB in surface water. Low levels of AR Salmonella (9.6%) and Escherichia coli (6.5%) were detected, while all Enterococcus were resistant to at least one tested antibiotic. Fewer than 20% of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (17.3%) and carbapenem-resistant Enterobacteriaceae (CRE) (7.7%) were recovered. Six ARGs were detected using qPCR, primarily the erythromycin-resistance gene, ermB. Of the 26 antibiotics measured, almost all water samples (98.7%) had detectable levels of antibiotics. Analysis of wastewater samples from three WWTPs showed that WWTPs did not completely remove AR contaminants. ARGs and antibiotics were detected in all the WWTP effluent discharges, indicating that WWTPs are the source of AR contaminants in receiving water. However, no significant difference in ARGs and antibiotics between the upstream and downstream water suggests that there are other sources of AR contamination. The widespread occurrence and abundance of medically important antibiotics, bacteria resistant to antibiotics used for human and veterinary purposes, and the genes associated with resistance to these antibiotics, may potentially pose risks to the local populations exposed to these water sources.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Treatment of antibiotic-manufacturing wastewater enriches for Aeromonas veronii, a zoonotic antibiotic-resistant emerging pathogen

Antibiotic-manufacturing wastewater treatment plants primarily target chemical pollutants, but their processes may select for antibiotic-resistant pathogens and antibiotic resistance genes. Leveraging the combined strengths of deep metagenomic sequencing, 16S rRNA gene sequencing, quantitative polymerase chain reaction, and bacterial culturing, we investigated bacterial communities and antibiotic resistomes across eleven treatment units in a full-scale antibiotic-manufacturing wastewater treatment plant processing wastewater from a β-lactam manufacturing facility. Both bacterial communities and antibiotic resistance gene compositions varied across the treatment units, but were associated. Certain antibiotic resistance gene persisted through treatment, either carried by identical bacterial species, or linked to mobile genetic elements in different species. Despite the satisfactory performance in chemical removal, this plant continuously enriched zoonotic antibiotic-resistant Aeromonas veronii (an emerging pathogen responsible for substantial economic losses in aquaculture and human health) from influent to effluent, probably due to prolonged β-lactam selection pressure and aquatic nature of A. veronii. This enrichment resulted in a significantly higher abundance of A. veronii than other aquatic samples worldwide. Furthermore, the closest evolutionary relative to the retrieved A. veronii was an isolate obtained from the stool of a local diarrhea patient. These findings highlighted a substantial public health risk posed by antibiotic-manufacturing wastewater treatment, underlining its potential role in enriching and disseminating zoonotic antibiotic-resistant pathogens. Beyond chemical monitoring, enhanced surveillance of antibiotic-resistant pathogens and antibiotic resistance genes is needed in effluent discharge standard for antibiotic-manufacturing wastewater treatment plants.

Wang, Xingshuo↗
DOE OSTI2021

DNA Breaks-Mediated Fitness Cost Reveals RNase HI as a New Target for Selectively Eliminating Antibiotic-Resistant Bacteria

Abstract Antibiotic resistance often generates defects in bacterial growth called fitness cost. Understanding the causes of this cost is of paramount importance, as it is one of the main determinants of the prevalence of resistances upon reducing antibiotics use. Here we show that the fitness costs of antibiotic resistance mutations that affect transcription and translation in Escherichia coli strongly correlate with DNA breaks, which are generated via transcription–translation uncoupling, increased formation of RNA–DNA hybrids (R-loops), and elevated replication–transcription conflicts. We also demonstrated that the mechanisms generating DNA breaks are repeatedly targeted by compensatory evolution, and that DNA breaks and the cost of resistance can be increased by targeting the RNase HI, which specifically degrades R-loops. We further show that the DNA damage and thus the fitness cost caused by lack of RNase HI function drive resistant clones to extinction in populations with high initial frequency of resistance, both in laboratory conditions and in a mouse model of gut colonization. Thus, RNase HI provides a target specific against resistant bacteria, which we validate using a repurposed drug. In summary, we revealed key mechanisms underlying the fitness cost of antibiotic resistance mutations that can be exploited to specifically eliminate resistant bacteria.

Balbontín, Roberto↗
DOE OSTI2023

An optogenetic toolkit for light-inducible antibiotic resistance

Abstract Antibiotics are a key control mechanism for synthetic biology and microbiology. Resistance genes are used to select desired cells and regulate bacterial populations, however their use to-date has been largely static. Precise spatiotemporal control of antibiotic resistance could enable a wide variety of applications that require dynamic control of susceptibility and survival. Here, we use light-inducible Cre recombinase to activate expression of drug resistance genes in Escherichia coli . We demonstrate light-activated resistance to four antibiotics: carbenicillin, kanamycin, chloramphenicol, and tetracycline. Cells exposed to blue light survive in the presence of lethal antibiotic concentrations, while those kept in the dark do not. To optimize resistance induction, we vary promoter, ribosome binding site, and enzyme variant strength using chromosome and plasmid-based constructs. We then link inducible resistance to expression of a heterologous fatty acid enzyme to increase production of octanoic acid. These optogenetic resistance tools pave the way for spatiotemporal control of cell survival.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Dead but Not Forgotten: How Extracellular DNA, Moisture, and Space Modulate the Horizontal Transfer of Extracellular Antibiotic Resistance Genes in Soil

Antibiotic-resistant bacteria and the spread of antibiotic resistance genes (ARGs) pose a serious risk to human and veterinary health. While many studies focus on the movement of live antibiotic-resistant bacteria to the environment, it is unclear whether extracellular ARGs (eARGs) from dead cells can transfer to live bacteria to facilitate the evolution of antibiotic resistance in nature. Here, we use eARGs from dead, antibiotic-resistant Pseudomonas stutzeri cells to track the movement of eARGs to live P. stutzeri cells via natural transformation, a mechanism of horizontal gene transfer involving the genomic integration of eARGs. In sterile, antibiotic-free agricultural soil, we manipulated the eARG concentration, soil moisture, and proximity to eARGs. We found that transformation occurred in soils inoculated with just 0.25 μg of eDNA g –1 soil, indicating that even low concentrations of soil eDNA can facilitate transformation (previous estimates suggested ~2 to 40 μg eDNA g –1 soil). When eDNA was increased to 5 μg g –1 soil, there was a 5-fold increase in the number of antibiotic-resistant P. stutzeri cells. We found that eARGs were transformed under soil moistures typical of terrestrial systems (5 to 30% gravimetric water content) but inhibited at very high soil moistures (>30%). Altogether, this work demonstrates that dead bacteria and their eARGs are an overlooked path to antibiotic resistance. More generally, the spread of eARGs in antibiotic-free soil suggests that transformation allows genetic variants to establish in the absence of antibiotic selection and that the soil environment plays a critical role in regulating transformation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Antibacterial Minerals: A geochemical approach to combating antibiotic resistance

The rapid rise of antibiotic resistant bacteria is seriously threatening our ability to treat lifethreatening infections. As a result, our approach to medicine and agriculture will require significant changes if we are to successfully maintain current levels of healthcare and food security. Certain naturally occurring clays have been shown to harbor antimicrobial properties and kill antibiotic resistant bacteria. These clays have been proposed as a new paradigm for fighting the potentially devastating effects of the post antibiotic era. However, natural samples, by their inherent properties, exhibit variable antibacterial effectiveness and the synthesis of minerals with reproducible antibacterial activity is needed. Our project focused on 3 specific aims; 1) develop synthetic versions of naturally occurring bactericidal minerals to control the chemical purity and antibacterial potency, 2) determine how effective these mineral formulations are at killing antibiotic resistant bacteria and 3) investigate the response of human skin cell cultures to these antibacterial minerals. Utilizing hydrothermal based methods our team was able to reproduce the antibacterial activity observed in natural antibacterial minerals, while eliminating unwanted elemental impurities. Importantly, we were able to create a mineral based bactericide that has reproducible reactivity that could provide a consistent dose response. These antibacterial mineral formulations are effective at killing common hospital acquired antibiotic resistant bacteria while providing minimal toxicity to human fibroblasts. Our research has optimized the antibacterial properties of antibacterial minerals to allow greater efficacy from a public health perspective.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Synthetic antibacterial minerals: harnessing a natural geochemical reaction to combat antibiotic resistance

The overuse of antibiotics in clinical and livestock settings is accelerating the selection of multidrug resistant bacterial pathogens. Antibiotic resistant bacteria result in increased mortality and financial strain on the health care and livestock industry. The development of new antibiotics has stalled, and novel strategies are needed as we enter the age of antibiotic resistance. Certain naturally occurring clays have been shown to have antimicrobial properties and kill antibiotic resistant bacteria. Harnessing the activity of compounds within these clays that harbor antibiotic properties offers new therapeutic opportunities for fighting the potentially devastating effects of the post antibiotic era. However, natural samples are highly heterogenous and exhibit variable antibacterial effectiveness, therefore synthesizing minerals of high purity with reproducible antibacterial activity is needed. Here we describe for the first time synthetic smectite clay minerals and Fe-sulfide microspheres that reproduce the geochemical antibacterial properties observed in natural occurring clays. We show that these mineral formulations are effective at killing the ESKAPE pathogens ( Enterococcus sp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter sp., Pseudomonas aeruginosa and Enterobacter sp.) by maintaining Fe 2+ solubility and reactive oxygen species (ROS) production while buffering solution pH, unlike the application of metals alone. Our results represent the first step in utilizing a geochemical process to treat antibiotic resistant topical or gastrointestinal infections in the age of antibiotic resistance.

58 GEOSCIENCES↗
DOE OSTI2022

Diversity of Antibiotic Resistance genes and Transfer Elements-Quantitative Monitoring (DARTE-QM): a method for detection of antimicrobial resistance in environmental samples

Effective monitoring of antibiotic resistance genes and their dissemination in environmental ecosystems has been hindered by the cost and efficiency of methods available for the task. We developed the Diversity of Antibiotic Resistance genes and Transfer Elements-Quantitative Monitoring (DARTE-QM), a method implementing TruSeq high-throughput sequencing to simultaneously sequence thousands of antibiotic resistant gene targets representing a full-spectrum of antibiotic resistance classes common to environmental systems. In this study, we demonstrated DARTE-QM by screening 662 antibiotic resistance genes within complex environmental samples originated from manure, soil, and livestock feces, in addition to a mock-community reference to assess sensitivity and specificity. DARTE-QM offers a new approach to studying antibiotic resistance in environmental microbiomes, showing advantages in efficiency and the ability to scale for many samples. This method provides a means of data acquisition that will alleviate some of the obstacles that many researchers in this area currently face.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Antibiotic Resistance in Plastisphere

Microbial life on plastic debris, called plastisphere, has invoked special attention on aquatic ecosystems as emerging habitats for antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB). There is scarce information concerning how properties of plastics influence ARGs and ARB, the effect of biofilms on enrichment of ARGs and ARB, and, especially, the influence of plastic transformation on ARGs and ARB. Limited research has shown that microplastic (MP) surfaces influence proliferation of antibiotic resistance (AR), aged MPs exhibit increased toxicity due to more adsorption-desorption of AR, and MP transformation is correlated with disseminating AR. Prevention measures of AR include minimizing MP releasing into aquatic environments and sewage treatment plants. The future research should aim to identify the interface mechanisms of transformed MNPs and antibiotics alone, or mixed with other contaminants, property changes of MNPs, and associated toxicity evaluation.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRSDate not supplied

Enterococci in Space: Adaptation, Antibiotic Resistance, and Clinical Implications

Enterococci are gram-positive bacteria that originated when our ancient animal ancestors emerged from the oceans to live on land, and brought their gut flora with them. Enterococcus faecalis (EF) and Enterococcus faecium, are common human commensals and can harbor multidrug resistance. Both have been previously isolated from the International Space Station (ISS). Likely as a consequence of their evolutionary origins, enterococci show remarkable stress resistance within, but also outside, their human hosts. Their antibiotic resistance, coupled with tolerance to desiccation, starvation, and disinfection, make some EF strains potent pathogens in the built environment (e.g., hospitals), and a potential risk to crew health during space missions. Here we describe our planned flight studies, currently in development. Genomic Enumeration of Antibiotic Resistance in Space (GEARS) will characterize the frequency and genomic identity of antibiotic resistant organisms, including enterococci, on the ISS, and expand our future in-space sequencing-based diagnostic capabilities. Enterococcus Growth Advantage on ISS via Tn-seq (EnteroGAIT) will assess the evolutionary selective pressure of the space environment (microgravity, space radiation) using EF as a model system during a long-duration culture and persistence experiment. Adaptation & Evolution of Resilient Enterococcus in Space (AERES) will study existing and newly identified isolates to characterize the “natural” evolutionary history of EF on Earth and in space to reveal mechanisms of microbial adaption including, possibly, natural selection. Our work to date has identified that EF ISS isolates share virulence factors found in clinical strains and commensals, and revealed limitations of current pathogenicity assessment tools. While ISS isolates were, in some cases, multi-drug resistant, current data suggests these are largely commensal strains. Our work will further refine potential crew health risks and improve understanding of EF adaptation to the built environment, of great relevance on Earth where EF is the second leading cause of hospital acquired infection.

Jordan McKaig↗
DOE OSTI2022

Insight into co-hosts of nitrate reduction genes and antibiotic resistance genes in an urban river of the qinghai-tibet plateau

Microbial co-hosts of nitrate reduction genes (NRGs) and antibiotic resistance genes (ARGs) have been recently reported, but their ecology and biochemical role in urban waterways remain largely unknown. Here, we collected 69 surface water and sediment samples in the Huangshui River on the Qinghai-Tibet Plateau during the wet and dry season associated with comparatively low and high antibiotic levels. Using metagenomic sequencing, we retrieved 278 medium-to-high-quality metagenome-assembled genomes (MAGs) of NRG-ARG co-hosts, mainly belonging to the phyla Proteobacteria, Actinobacteriota, and Bacteroidota. Of microorganisms carrying ARGs, a high proportion (75.3?94.9%) also encoded NRGs, supporting nitrate reducing bacteria as dominant hosts of ARGs. Seasonal changes in antibiotic levels corresponded to significant variation in the relative abundance and community composition of NRG-ARG co-host in both water and sediments, resulting in a concomitant change in antibiotic resistance pathways. In contrast, the contribution of NRG-ARG co-hosts to nitrate reduction was stable between seasons. Further, we identify specific antibiotics (e.g., sulphonamides) and microbial taxa (e.g., Acinetobacter and Hafnia) that may disproportionately impact these relationships to serve as a basis for laboratory investigations into bioremediation strategies. Our study suggests that highly abundant nitrate reducing microorganisms in contaminated environments may also directly impact human health as carriers of antibiotic resistance.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Cartography of opportunistic pathogens and antibiotic resistance genes in a tertiary hospital environment

Although disinfection is key to infection control, the colonization patterns and resistomes of hospital-environment microbes remain underexplored. We report the first extensive genomic characterization of microbiomes, pathogens and antibiotic resistance cassettes in a tertiary-care hospital, from repeated sampling (up to 1.5 years apart) of 179 sites associated with 45 beds. Deep shotgun metagenomics unveiled distinct ecological niches of microbes and antibiotic resistance genes characterized by biofilm-forming and human-microbiome-influenced environments with corresponding patterns of spatiotemporal divergence. Quasi-metagenomics with nanopore sequencing provided thousands of high-contiguity genomes, phage and plasmid sequences (>60% novel), enabling characterization of resistome and mobilome diversity and dynamic architectures in hospital environments. Phylogenetics identified multidrug-resistant strains as being widely distributed and stably colonizing across sites. Comparisons with clinical isolates indicated that such microbes can persist in hospitals for extended periods (>8 years), to opportunistically infect patients. These findings highlight the importance of characterizing antibiotic resistance reservoirs in hospitals and establish the feasibility of systematic surveys to target resources for preventing infections.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Dielectrophoresis assisted rapid, selective and single cell detection of antibiotic resistant bacteria with G-FETs

Time-consuming, expensive and low sensitivity diagnostic methods used for monitoring bacterial infections lead to unnecessary or delays in prescription of the right antibiotic treatment. Determining an optimal clinical treatment requires rapid detection and identification of pathogenic bacteria and their sensitivity to specific antimicrobials. However, diagnostic devices that meet all of these criteria have proven elusive thus far. Graphene field effect transistors (G-FET) are a promising solution, since they are highly sensitive to chemical/biological modification, can have fast detection times and can be placed on different substrates. Here, by integrating specific peptide probes over G-FETs, we present a proof-of-concept study for species and strain specific label-free detection of clinical strains of pathogenic bacteria with high specificity and sensitivity. We found that pyrene-conjugated peptides immobilized on G-FETs were capable of detecting pathogenic Staphylococcus aureus at the single-cell level and discriminate against other gram-positive and gram-negative bacterial pathogens. A similar device was able to discriminate between antibiotic resistant and sensitive strains of Acinetobacter baumannii , suggesting that these devices can also be used for detecting antibiotic resistive pathogens. Furthermore, a new means of enhancing attachment, electric-field assisted binding, reduced the detection limit to 104 cells/ml and the detection time to below 5 minutes. Here, the combination of single step attachment, inexpensive production, rapid, selective and sensitive detection suggest G-FETs plus pyrene-conjugated peptides are a new platform for solving major challenges faced in point of care diagnostics to fight infectious diseases and antimicrobial resistance.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
NASA NTRSDate not supplied

Characterizing Antibiotic Resistance in Microgravity Environments

The gram-positive bacterium Staphylococcus aureus and the gram-negative Pseudomonas aeruginosa are two of NASA’s designated “medically important microorganisms” commonly co-isolated from spaceflight environments like the International Space Station (ISS). Prior studies demonstrate evidence of increased virulence and antibiotic resistance of each bacterium when grown as single species in space. “Characterizing Antibiotic Resistance in Microgravity Environments” (CARMEn) is an autonomous 30-day ISS payload experiment probing the phenotypic changes of S. aureus and P. aeruginosa biofilms grown together in microgravity. Phenotypic changes are probed through three parallel experiments measuring Extracellular Matrix (ECM) production, antibiotic tolerance, and RNA expression respectively. The ECM experiment uses time-lapse imaging to collect observational morphological data from biofilms stained with Congo Red and Coomassie Blue, the antibiotic tolerance experiment utilizes E-strip testing once samples return to Earth, and RNA expression is measured through RNAseq of samples treated with RNAProtect® during spaceflight.

Antibiotic resistance↗
DOE OSTI2021

Metagenomic strategies identify diverse integron–integrase and antibiotic resistance genes in the Antarctic environment

The objective of this study is to identify and analyze integrons and antibiotic resistance genes (ARGs) in samples collected from diverse sites in terrestrial Antarctica. Integrons were studied using two independent methods. One involved the construction and analysis of intI gene amplicon libraries. In addition, we sequenced 17 metagenomes of microbial mats and soil by high-throughput sequencing and analyzed these data using the IntegronFinder program. As expected, the metagenomic analysis allowed for the identification of novel predicted intI integrases and gene cassettes (GCs), which mostly encode unknown functions. However, some intI genes are similar to sequences previously identified by amplicon library analysis in soil samples collected from non-Antarctic sites. ARGs were analyzed in the metagenomes using ABRIcate with CARD database and verified if these genes could be classified as GCs by IntegronFinder. We identified 53 ARGs in 15 metagenomes, but only four were classified as GCs, one in MTG12 metagenome (Continental Antarctica), encoding an aminoglycoside-modifying enzyme (AAC(6´)acetyltransferase) and the other three in CS1 metagenome (Maritime Antarctica). One of these genes encodes a class D β-lactamase (blaOXA-205) and the other two are located in the same contig. One is part of a gene encoding the first 76 amino acids of aminoglycoside adenyltransferase (aadA6), and the other is a qacG2 gene.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Colistin resistance plasmids dually enhance bacterial virulence and antibiotic resistance via surface polysaccharide biosynthesis

Plasmids carrying the mobilized colistin-resistance gene mcr-1 are prevalent among multidrug-resistant Gram-negative pathogens, yet their broad impact on bacterial physiology and virulence remains unclear. Here, we demonstrate that acquisition of an mcr-1 plasmid concurrently increases antimicrobial resistance and pathogenicity in Escherichia coli. On the same plasmid, the XRE-family transcriptional regulator EcaR cooperates with MCR-1 to activate the wec operon, driving biosynthesis of two surface polysaccharides: enterobacterial common antigen (ECA) and a high-molecular-weight O-chain. Expression of these surface polysaccharides increases bile resistance and virulence in a murine model and further elevates colistin resistance. MCR-1 enhances transcription of upstream genes in the wec operon, whereas EcaR directly activates an internal promoter (PwecE) to induce downstream gene expression. Thus, both components are required for surface polysaccharide expression, and deletion of either abolishes the phenotype. Genomic analysis of publicly available mcr plasmids reveals widespread co-occurrence of mcr-1 and ecaR on IncI2 and IncX4 plasmids, indicating their functional complementarity. These findings uncover a mechanism by which resistance plasmids remodel the bacterial surface, linking horizontal gene transfer to coordinated regulation of antimicrobial resistance and virulence.

Antimicrobial resistance↗
DOE OSTI2023

Mapping the determinants of catalysis and substrate specificity of the antibiotic resistance enzyme CTX-M β-lactamase

Abstract CTX-M β-lactamases are prevalent antibiotic resistance enzymes and are notable for their ability to rapidly hydrolyze the extended-spectrum cephalosporin, cefotaxime. We hypothesized that the active site sequence requirements of CTX-M-mediated hydrolysis differ between classes of β-lactam antibiotics. Accordingly, we use codon randomization, antibiotic selection, and deep sequencing to determine the CTX-M active-site residues required for hydrolysis of cefotaxime and the penicillin, ampicillin. The study reveals positions required for hydrolysis of all β-lactams, as well as residues controlling substrate specificity. Further, CTX-M enzymes poorly hydrolyze the extended-spectrum cephalosporin, ceftazidime. We further show that the sequence requirements for ceftazidime hydrolysis follow those of cefotaxime, with the exception that key active-site omega loop residues are not required, and may be detrimental, for ceftazidime hydrolysis. These results provide insights into cephalosporin hydrolysis and demonstrate that changes to the active-site omega loop are likely required for the evolution of CTX-M-mediated ceftazidime resistance.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2015

EcAMSat: Effect of Space-Flight on Antibiotic Resistance of a Pathogenic Bacterium and its Genetic Basis

Human immune response is compromised in space and incidence of urinary tract infections (UTI) in astronauts has been reported. We have found that the causative agent of UTI, the uropathogenic Escherichia coli, becomes more resistant to gentamicin (Gm), which is commonly used to treat this disease, under modeled microgravity conditions (MMG), the increase being controlled by the stress response master regulator, σs. While the wild type bacterium becomes virtually invincible under MMG, the strain missing this sigma factor barely survives. We report here preparatory ground work for testing this finding in space flight on a nanosatellite. We have shown that the effect of Gm treatment on culture viability is directly correlated to increased Alamar Blue (AB) reduction; we have identified conditions to keep the experimental elements - the bacterial cultures, Gm, and AB - in a state of viability and potency to permit successful spaceflight experimentation given the necessary constraints. Spaceflight kinetics of AB reduction will be transmitted from the satellite via telemetry. The PharmaSat hardware previously used for space experimentation with yeast was modified to permit studies with bacteria by reducing the filter pore size and increasing fluidics volume to enable more fluid exchanges. Several verification tests have been run using the nanosatellite's flight software and prototype hardware. Cells were grown to stationary phase to induce the σs-controlled stress resistance and treated with Gm. Without Gm, the mutant took longer than the wild type to reduce the AB; this time difference increased almost 8 fold at 55 μg/mL Gm concentration. Thus, using flight hardware the mutant shows similarly increased sensitivity to Gm compared to the wild type to that found in our pilot microtiter plate experiments. Previous inflight experiments have given contradictory results concerning bacterial antibiotic resistance; none has yet explored the involvement of specific genes in this phenomenon. With our system ready to fly in late 2015/early 2016, these questions can be approached

uropathogenic E. coli↗