Biology subjects

Rotman, E. R.

Publications and source records attributed to Rotman, E. R..

3 recordsLinked to original sources

bioRxiv2025

Sedative choice alters Klebsiella pneumoniae lung pathogenesis and dissemination

Klebsiella pneumoniae make up 85% of carbapenem-resistant Enterobacteriaceae (CRE), bacteria that have become an urgent threat to public health. K. pneumoniae is largely transmitted in healthcare settings, where inpatients and outpatients are often anesthetized with the widely-used anesthetic induction agent propofol. Recent evidence obtained from rodent infection models indicates that propofol exposure can dramatically increase host susceptibility to microbial infections. Given that intensive care patients who are at a greater risk for K. pneumoniae lung infections are often given propofol during their hospitalization, we investigated the outcome of K. pneumoniae infections in mice briefly sedated with either propofol or ketamine/xylazine as control. Propofol-sedated mice experienced more rapid dissemination from the lungs to secondary sites of infection and their lungs exhibited more severe pathology. Based on these observations, we investigated bacterial factors involved in infection and dissemination in mice with propofol or ketamine/xylazine sedation using a high throughput insertion sequencing (INSeq) approach. We identified numerous novel potential virulence factors together with previously identified gene products, confirming the validity of our screen. We further characterized a mutant lacking the phospholipid retrograde trafficking chaperone MlaC and found that the degree of mutant attenuation was dependent upon sedation method. These results highlight the importance of sedative choice when studying hospital-acquired microbial infections and suggest that sedation can influence outcome of K. pneumoniae infection and dissemination in animal models. IMPORTANCEHost sedation by either propofol or ketamine exposure differentially impacted the severity of K. pneumoniae lung infection following intranasal inoculation of mice. While propofol-sedated mice exhibited increased lung pathology, some bacterial mutants, such as those lacking the MlaC gene product associated with the maintenance of inner and outer membrane lipid asymmetry, exhibited more severe attenuation following propofol sedation versus ketamine/xylazine. Given the dominating use of propofol in health care settings for the induction and maintenance of anesthesia, procedural sedation, and sedation for intensive care patients, this work provides important perspective as to how the choice of an anesthetic agent may impact the outcome of healthcare-associated infections.

microbiology↗

bioRxiv2020

Bacterial gene essentiality under modeled microgravity

To support long-duration spaceflight, identifying genes that enable microbial survival and stability under space stressors is crucial, as these factors can affect both host health and in-space biomanufacturing efforts. Our objective was to determine what bacterial genes are required for growth in culture under modeled, or simulated, microgravity conditions compared to normal gravity controls. We focused on the marine bacterium Vibrio fischeri, which forms a monospecific symbiosis with the Hawaiian bobtail squid, Euprymna scolopes. The symbiosis has been studied during spaceflight and in ground-based modeled microgravity conditions. Using transposon insertion sequencing (INSeq), we identified dozens of genes that exhibited fitness defects under both conditions, yet we identified relatively few genes with differential effects under modeled microgravity or gravity specifically. We additionally compared RNA-seq and INSeq data and determined that expression under microgravity was not predictive of the essentiality of a given gene. In summary, empirical determination of conditional gene essentiality identifies few microgravity-specific genes for environmental growth of V. fischeri, suggesting that the condition of microgravity has a minimal impact on symbiont gene requirement during growth in media. These findings suggest that maintaining beneficial microbial communities during spaceflight, and enabling their use in biomanufacturing applications, may require minimal genetic adaptation, easing the challenges of supporting healthy symbiotic relationships on long-duration missions.

microbiology↗

bioRxiv2018

Natural strain diversity reveals novel biofilm regulation in squid-colonizing Vibrio fischeri

The mutualistic symbiont Vibrio fischeri builds a symbiotic biofilm during colonization of squid hosts. Regulation of the exopolysaccharide component, termed Syp, has been examined in strain ES114, where production is controlled by a phosphorelay that includes the inner membrane hybrid histidine kinase RscS. Most strains that lack RscS or encode divergent RscS proteins cannot colonize a squid host unless RscS from a squid symbiont is heterologously expressed. In this study, we examine V. fischeri isolates worldwide to understand the landscape of biofilm regulation during beneficial colonization. We provide a detailed study of three distinct evolutionary groups of V. fischeri and find that while the RscS-Syp biofilm pathway is required in one of the groups, two other groups of squid symbionts require Syp independent of RscS. Mediterranean squid symbionts, including V. fischeri SR5, colonize without an RscS homolog encoded in their genome. Additionally, Group A V. fischeri strains, which form a tightly-related clade of Hawaii isolates, have a frameshift in rscS and do not require the gene for squid colonization or competitive fitness. These same strains have a frameshift in sypE, and we provide evidence that this Group A sypE allele leads to an upregulation in biofilm activity. This work thus describes the central importance of Syp biofilm in colonization of diverse isolates, and demonstrates that significant evolutionary transitions correspond to regulatory changes in the syp pathway.\n\nIMPORTANCEBiofilms are surface-associated, matrix-encased bacterial aggregates that exhibit enhanced protection to antimicrobial agents. Previous work has established the importance of biofilm formation by a strain of luminous Vibrio fischeri bacteria as the bacteria colonize their host, the Hawaiian bobtail squid. In this study, expansion of this work to many natural isolates revealed that biofilm genes are universally required, yet there has been a shuffling of the regulators of those genes. This work provides evidence that even when bacterial behaviors are conserved, dynamic regulation of those behaviors can underlie evolution of the host colonization phenotype. Furthermore, this work emphasizes the importance of investigating natural diversity as we seek to understand molecular mechanisms in bacteria.

microbiology↗