Conservation of the Low-shear Modeled Microgravity Response in Enterobacteriaceae and Analysis of the trp Genes in this Response

Anjali Soni 1, 2, Laura O’Sullivan 1, 3, Laura N Quick 1, 4, C. Mark Ott 5, Cheryl A Nickerson 6, James W Wilson*, 1
1 Villanova University, Biology Department, 800 Lancaster Avenue, Villanova, PA 19085
2 Virginia Commonwealth University, School of Dentistry, Richmond, VA23298
3 University of Pennsylvania,School of Veterinary Medicine, Philadelphia, PA 19104
4 Children’s Hospital of Philadelphia, Philadelphia, PA 19104
5 NASA/Johnson Space Center, Habitability and Environmental Factors Division, Houston, TX77058
6 Arizona State University, Biodesign Institute, Center for Infectious Diseases and Vaccinology, Tempe, AZ85281

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© Soni et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the Villanova University, Biology Department, 800 Lancaster Avenue, Villanova, PA 19085; Tel: 610-519-3037; Fax: 610-519-7863; E-mail:


Low fluid shear force, including that encountered in microgravity models, induces bacterial responses, but the range of bacteria capable of responding to this signal remains poorly characterized. We systematically analyzed a range of Gram negative Enterobacteriaceae for conservation of the low-shear modeled microgravity (LSMMG) response using phenotypic assays, qPCR, and targeted mutations. Our results indicate LSMMG response conservation across Enterobacteriacae with potential variance in up- or down-regulation of a given response depending on genus. Based on the data, we analyzed the role of the trp operon genes and the TrpR regulator in the LSMMG response using targeted mutations in these genes in S. Typhimurium and E. coli. We found no alteration of the LSMMG response compared to WT in these mutant strains under the conditions tested here. To our knowledge, this study is first-of-kind for Citrobacter, Enterobacter, and Serratia, presents novel data for Escherichia, and provides the first analysis of trp genes in LSMMG responses. This impacts our understanding of how LSMMG affects bacteria and our ability to modify bacteria with this condition in the future.

Keywords: Enterobacteriaceae, environmental response, low shear modeled microgravity, rotating wall vessel, Salmonella Typhimurium.