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Adaptation to simulated microgravity in Streptococcus mutans. NPJ Microgravity 2022; 8:17. [PMID: 35654802 PMCID: PMC9163064 DOI: 10.1038/s41526-022-00205-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 05/13/2022] [Indexed: 11/08/2022] Open
Abstract
Long-term space missions have shown an increased incidence of oral disease in astronauts’ and as a result, are one of the top conditions predicted to impact future missions. Here we set out to evaluate the adaptive response of Streptococcus mutans (etiological agent of dental caries) to simulated microgravity. This organism has been well studied on earth and treatment strategies are more predictable. Despite this, we are unsure how the bacterium will respond to the environmental stressors in space. We used experimental evolution for 100-days in high aspect ratio vessels followed by whole genome resequencing to evaluate this adaptive response. Our data shows that planktonic S. mutans did evolve variants in three genes (pknB, SMU_399 and SMU_1307c) that can be uniquely attributed to simulated microgravity populations. In addition, collection of data at multiple time points showed mutations in three additional genes (SMU_399, ptsH and rex) that were detected earlier in simulated microgravity populations than in the normal gravity controls, many of which are consistent with other studies. Comparison of virulence-related phenotypes between biological replicates from simulated microgravity and control orientation cultures generally showed few changes in antibiotic susceptibility, while acid tolerance and adhesion varied significantly between biological replicates and decreased as compared to the ancestral populations. Most importantly, our data shows the importance of a parallel normal gravity control, sequencing at multiple time points and the use of biological replicates for appropriate analysis of adaptation in simulated microgravity.
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Böhme K, Heroven AK, Lobedann S, Guo Y, Stolle AS, Dersch P. The Small Protein YmoA Controls the Csr System and Adjusts Expression of Virulence-Relevant Traits of Yersinia pseudotuberculosis. Front Microbiol 2021; 12:706934. [PMID: 34413840 PMCID: PMC8369931 DOI: 10.3389/fmicb.2021.706934] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 07/12/2021] [Indexed: 11/24/2022] Open
Abstract
Virulence gene expression of Yersinia pseudotuberculosis changes during the different stages of infection and this is tightly controlled by environmental cues. In this study, we show that the small protein YmoA, a member of the Hha family, is part of this process. It controls temperature- and nutrient-dependent early and later stage virulence genes in an opposing manner and co-regulates bacterial stress responses and metabolic functions. Our analysis further revealed that YmoA exerts this function by modulating the global post-transcriptional regulatory Csr system. YmoA pre-dominantly enhances the stability of the regulatory RNA CsrC. This involves a stabilizing stem-loop structure within the 5′-region of CsrC. YmoA-mediated CsrC stabilization depends on H-NS, but not on the RNA chaperone Hfq. YmoA-promoted reprogramming of the Csr system has severe consequences for the cell: we found that a mutant deficient of ymoA is strongly reduced in its ability to enter host cells and to disseminate to the Peyer’s patches, mesenteric lymph nodes, liver and spleen in mice. We propose a model in which YmoA controls transition from the initial colonization phase in the intestine toward the host defense phase important for the long-term establishment of the infection in underlying tissues.
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Affiliation(s)
- Katja Böhme
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Ann Kathrin Heroven
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Stephanie Lobedann
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Yuzhu Guo
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), Medical Faculty Münster, University of Münster, Münster, Germany
| | - Anne-Sophie Stolle
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), Medical Faculty Münster, University of Münster, Münster, Germany
| | - Petra Dersch
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), Medical Faculty Münster, University of Münster, Münster, Germany
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Abstract
Microbial research in space is being conducted for almost 50 years now. The closed system of the International Space Station (ISS) has acted as a microbial observatory for the past 10 years, conducting research on adaptation and survivability of microorganisms exposed to space conditions. This adaptation can be either beneficial or detrimental to crew members and spacecraft. Therefore, it becomes crucial to identify the impact of two primary stress conditions, namely, radiation and microgravity, on microbial life aboard the ISS. Elucidating the mechanistic basis of microbial adaptation to space conditions aids in the development of countermeasures against their potentially detrimental effects and allows us to harness their biotechnologically important properties. Several microbial processes have been studied, either in spaceflight or using devices that can simulate space conditions. However, at present, research is limited to only a few microorganisms, and extensive research on biotechnologically important microorganisms is required to make long-term space missions self-sustainable.
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Affiliation(s)
- Swati Bijlani
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90089, USA
| | - Elisa Stephens
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90089, USA
| | - Nitin Kumar Singh
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | | | - Clay C C Wang
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, 1985 Zonal Avenue, Los Angeles, CA 90089, USA
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Growth and Antifungal Resistance of the Pathogenic Yeast, Candida Albicans, in the Microgravity Environment of the International Space Station: An Aggregate of Multiple Flight Experiences. Life (Basel) 2021; 11:life11040283. [PMID: 33801697 PMCID: PMC8067245 DOI: 10.3390/life11040283] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/25/2021] [Accepted: 03/25/2021] [Indexed: 12/13/2022] Open
Abstract
This report was designed to compare spaceflight-induced cellular and physiological adaptations of Candida albicans cultured in microgravity on the International Space Station across several payloads. C. albicans is a common opportunistic fungal pathogen responsible for a variety of superficial infections as well as systemic and more severe infections in humans. Cumulatively, the propensity of this organism to be widespread through the population, the ability to produce disease in immunocompromised individuals, and the tendency to respond to environmental stress with characteristics associated with increased virulence, require a better understanding of the yeast response to microgravity for spaceflight crew safety. As such, the responses of this yeast cultivated during several missions using two in-flight culture bioreactors were analyzed and compared herein. In general, C. albicans had a slightly shorter generation time and higher growth propensity in microgravity as compared to terrestrial controls. Rates of cell filamentation differed between bioreactors, but were low and not significantly different between flight and terrestrial controls. Viable cells were retrieved and cultured, resulting in a colony morphology that was similar between cells cultivated in flight and in terrestrial control conditions, and in contrast to that previously observed in a ground-based microgravity analog system. Of importance, yeast demonstrated an increased resistance when challenged during spaceflight with the antifungal agent, amphotericin B. Similar levels of resistance were not observed when challenged with the functionally disparate antifungal drug caspofungin. In aggregate, yeast cells cultivated in microgravity demonstrated a subset of characteristics associated with virulence. In addition, and beyond the value of the specific responses of C. albicans to microgravity, this report includes an analysis of biological reproducibility across flight opportunities, compares two spaceflight hardware systems, and includes a summary of general flight and payload timelines.
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Green MJ, Aylott JW, Williams P, Ghaemmaghami AM, Williams PM. Immunity in Space: Prokaryote Adaptations and Immune Response in Microgravity. Life (Basel) 2021; 11:life11020112. [PMID: 33540536 PMCID: PMC7912908 DOI: 10.3390/life11020112] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 01/25/2021] [Accepted: 01/28/2021] [Indexed: 12/16/2022] Open
Abstract
Immune dysfunction has long been reported by medical professionals regarding astronauts suffering from opportunistic infections both during their time in space and a short period afterwards once back on Earth. Various species of prokaryotes onboard these space missions or cultured in a microgravity analogue exhibit increased virulence, enhanced formation of biofilms, and in some cases develop specific resistance for specific antibiotics. This poses a substantial health hazard to the astronauts confined in constant proximity to any present bacterial pathogens on long space missions with a finite number of resources including antibiotics. Furthermore, some bacteria cultured in microgravity develop phenotypes not seen in Earth gravity conditions, providing novel insights into bacterial evolution and avenues for research. Immune dysfunction caused by exposure to microgravity may increase the chance of bacterial infection. Immune cell stimulation, toll-like receptors and pathogen-associated molecular patterns can all be altered in microgravity and affect immunological crosstalk and response. Production of interleukins and other cytokines can also be altered leading to immune dysfunction when responding to bacterial infection. Stem cell differentiation and immune cell activation and proliferation can also be impaired and altered by the microgravity environment once more adding to immune dysfunction in microgravity. This review elaborates on and contextualises these findings relating to how bacteria can adapt to microgravity and how the immune system subsequently responds to infection.
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Affiliation(s)
- Macauley J. Green
- School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK; (M.J.G.); (J.W.A.)
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK; (P.W.); (A.M.G.)
| | - Jonathan W. Aylott
- School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK; (M.J.G.); (J.W.A.)
| | - Paul Williams
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK; (P.W.); (A.M.G.)
| | - Amir M. Ghaemmaghami
- School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK; (P.W.); (A.M.G.)
| | - Philip M. Williams
- School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK; (M.J.G.); (J.W.A.)
- Correspondence:
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Exploration of space to achieve scientific breakthroughs. Biotechnol Adv 2020; 43:107572. [PMID: 32540473 DOI: 10.1016/j.biotechadv.2020.107572] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/05/2020] [Accepted: 05/29/2020] [Indexed: 12/13/2022]
Abstract
Living organisms adapt to changing environments using their amazing flexibility to remodel themselves by a process called evolution. Environmental stress causes selective pressure and is associated with genetic and phenotypic shifts for better modifications, maintenance, and functioning of organismal systems. The natural evolution process can be used in complement to rational strain engineering for the development of desired traits or phenotypes as well as for the production of novel biomaterials through the imposition of one or more selective pressures. Space provides a unique environment of stressors (e.g., weightlessness and high radiation) that organisms have never experienced on Earth. Cells in the outer space reorganize and develop or activate a range of molecular responses that lead to changes in cellular properties. Exposure of cells to the outer space will lead to the development of novel variants more efficiently than on Earth. For instance, natural crop varieties can be generated with higher nutrition value, yield, and improved features, such as resistance against high and low temperatures, salt stress, and microbial and pest attacks. The review summarizes the literature on the parameters of outer space that affect the growth and behavior of cells and organisms as well as complex colloidal systems. We illustrate an understanding of gravity-related basic biological mechanisms and enlighten the possibility to explore the outer space environment for application-oriented aspects. This will stimulate biological research in the pursuit of innovative approaches for the future of agriculture and health on Earth.
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Sheet S, Yesupatham S, Ghosh K, Choi MS, Shim KS, Lee YS. Modulatory effect of low-shear modeled microgravity on stress resistance, membrane lipid composition, virulence, and relevant gene expression in the food-borne pathogen Listeria monocytogenes. Enzyme Microb Technol 2019; 133:109440. [PMID: 31874690 DOI: 10.1016/j.enzmictec.2019.109440] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 09/27/2019] [Accepted: 10/04/2019] [Indexed: 12/17/2022]
Abstract
The present study investigated the influence of low-shear modeled microgravity (LSMMG) conditions on Listeria monocytogenes stress response (heat, cold, and acid), membrane fatty acid composition, and virulence potential as well as stress-/virulence-associated gene expression. The results showed that LSMMG-cultivated cells had lower survival rate and lower D-values under heat and acid stress conditions compared to cells grown under normal gravity (NG). Interestingly, the cold resistance was elevated in cells cultivated under LSMMG conditions when compared to NG conditions. A higher amount of anteiso-branched chain fatty acids and lower ratio of iso/anteiso were observed in LSMMG cultured cells, which would contribute to increased membrane fluidity. Under LSMMG conditions, upregulated expression of cold stress-related genes (cspA, cspB, and cspD) was noticed but no change in expression was observed for heat (dnaK, groES, clpC, clpP, and clpE) and acid stress-related genes (sigB). The LSMMG-grown cells showed inferior virulence capacity in terms of infection, cell cycle arrest, and apoptosis induction in Caco-2 cells compared to those grown under NG conditions. Approximately 3.65, 2.13, 4.02, and 2.65-fold downregulation of prfA, hly, inlA, and bsh genes, respectively, in LSMMG-cultured cells might be the reason for reduced virulence. In conclusion, these findings suggest that growth under LSMMG conditions stimulates alterations in L. monocytogenes stress/virulence response, perhaps due to changes in lipid composition and related genes expression.
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Affiliation(s)
- Sunirmal Sheet
- Department of Forest Science and Technology, College of Agriculture and Life Sciences,Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do, Republic of Korea
| | - Sathishkumar Yesupatham
- Department of Forest Science and Technology, College of Agriculture and Life Sciences,Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do, Republic of Korea; Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daehak-Ro, Daejeon, Republic of Korea
| | - Kuntal Ghosh
- Department of Biological Sciences, Midnapore City College, Kuturiya, P.O. Bhadutala, Pin-721129, Paschim Medinipur, West Bengal, India
| | - Mi-Sook Choi
- Department of Forest Science and Technology, College of Agriculture and Life Sciences,Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do, Republic of Korea
| | - Kwan Seob Shim
- Department of Animal Biotechnology, College of Agriculture and Life Sciences, Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do, Republic of Korea
| | - Yang Soo Lee
- Department of Forest Science and Technology, College of Agriculture and Life Sciences,Chonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do, Republic of Korea.
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Evaluation of Acquired Antibiotic Resistance in Escherichia coli Exposed to Long-Term Low-Shear Modeled Microgravity and Background Antibiotic Exposure. mBio 2019; 10:mBio.02637-18. [PMID: 30647159 PMCID: PMC6336426 DOI: 10.1128/mbio.02637-18] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Stress factors experienced during space include microgravity, sleep deprivation, radiation, isolation, and microbial contamination, all of which can promote immune suppression (1, 2). Under these conditions, the risk of infection from opportunistic pathogens increases significantly, particularly during long-term missions (3). If infection occurs, it is important that the infectious agent should not be antibiotic resistant. Minimizing the occurrence of antibiotic resistance is, therefore, highly desirable. To facilitate this, it is important to better understand the long-term response of bacteria to the microgravity environment. This study demonstrated that the use of antibiotics as a preventive measure could be counterproductive and would likely result in persistent resistance to that antibiotic. In addition, unintended resistance to other antimicrobials might also occur as well as permanent genome changes that might have other unanticipated and undesirable consequences. The long-term response of microbial communities to the microgravity environment of space is not yet fully understood. Of special interest is the possibility that members of these communities may acquire antibiotic resistance. In this study, Escherichia coli cells were grown under low-shear modeled microgravity (LSMMG) conditions for over 1,000 generations (1000G) using chloramphenicol treatment between cycles to prevent contamination. The results were compared with data from an earlier control study done under identical conditions using steam sterilization between cycles rather than chloramphenicol. The sensitivity of the final 1000G-adapted strain to a variety of antibiotics was determined using Vitek analysis. In addition to resistance to chloramphenicol, the adapted strain acquired resistance to cefalotin, cefuroxime, cefuroxime axetil, cefoxitin, and tetracycline. In fact, the resistance to chloramphenicol and cefalotin persisted for over 110 generations despite the removal of both LSMMG conditions and trace antibiotic exposure. Genome sequencing of the adapted strain revealed 22 major changes, including 3 transposon-mediated rearrangements (TMRs). Two TMRs disrupted coding genes (involved in bacterial adhesion), while the third resulted in the deletion of an entire segment (14,314 bp) of the genome, which includes 14 genes involved with motility and chemotaxis. These results are in stark contrast with data from our earlier control study in which cells grown under the identical conditions without antibiotic exposure never acquired antibiotic resistance. Overall, LSMMG does not appear to alter the antibiotic stress resistance seen in microbial ecosystems not exposed to microgravity.
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Kim HW, Rhee MS. Novel Antibiotic Testing Approaches Reveal Reduced Antibiotic Efficacy Against Shiga Toxin-Producing Escherichia coli O157:H7 Under Simulated Microgravity. Front Microbiol 2019; 9:3214. [PMID: 30619237 PMCID: PMC6308135 DOI: 10.3389/fmicb.2018.03214] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 12/11/2018] [Indexed: 11/13/2022] Open
Abstract
As a foodborne and environmental pathogen, Shiga toxin-producing Escherichia coli O157:H7 could pose a health threat to immunocompromised astronauts during a space mission. In this study, novel approaches, including real-time testing and direct evaluation of resistance mechanisms, were used to evaluate antibiotic efficacy against E. coli O157:H7 under low-shear modeled microgravity (LSMMG) produced using a rotary cell culture system. When compared with normal gravity (NG), bacterial growth was increased under LSMMG in the presence of sub-inhibitory nalidixic acid concentrations and there was an accompanying up-regulation of stress-related genes. LSMMG also induced transcriptional changes of the virulence genes stx1 and stx2, highlighting the potential risk of inappropriate antibiotic use during a spaceflight. The degree of bacterial cell damage induced by the antibiotics was reduced under LSMMG, suggesting low induction of reactive oxygen species. Efflux pumps were also shown to play an important role in these responses. Increased cell filamentation was observed under LSMMG upon ampicillin treatment, possibly reflecting a protective mechanism against exposure to antibiotics. These observations indicate that, in the presence of antibiotics, the survival of E. coli O157:H7 is greater under LSMMG than under NG, indicating that antibiotic therapies may need to be adjusted during space missions.
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Affiliation(s)
- Hye Won Kim
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, South Korea
| | - Min Suk Rhee
- Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, South Korea
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10
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Huang B, Li DG, Huang Y, Liu CT. Effects of spaceflight and simulated microgravity on microbial growth and secondary metabolism. Mil Med Res 2018; 5:18. [PMID: 29807538 PMCID: PMC5971428 DOI: 10.1186/s40779-018-0162-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 04/26/2018] [Indexed: 01/01/2023] Open
Abstract
Spaceflight and ground-based microgravity analog experiments have suggested that microgravity can affect microbial growth and metabolism. Although the effects of microgravity and its analogs on microorganisms have been studied for more than 50 years, plausible conflicting and diverse results have frequently been reported in different experiments, especially regarding microbial growth and secondary metabolism. Until now, only the responses of a few typical microbes to microgravity have been investigated; systematic studies of the genetic and phenotypic responses of these microorganisms to microgravity in space are still insufficient due to technological and logistical hurdles. The use of different test strains and secondary metabolites in these studies appears to have caused diverse and conflicting results. Moreover, subtle changes in the extracellular microenvironments around microbial cells play a key role in the diverse responses of microbial growth and secondary metabolisms. Therefore, "indirect" effects represent a reasonable pathway to explain the occurrence of these phenomena in microorganisms. This review summarizes current knowledge on the changes in microbial growth and secondary metabolism in response to spaceflight and its analogs and discusses the diverse and conflicting results. In addition, recommendations are given for future studies on the effects of microgravity in space on microbial growth and secondary metabolism.
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Affiliation(s)
- Bing Huang
- Nanlou Respiratory Diseases Department, Chinese PLA General Hospital/Chinese PLA Postgraduate Medical School, Beijing, 100853, China
| | - Dian-Geng Li
- Nanlou Respiratory Diseases Department, Chinese PLA General Hospital/Chinese PLA Postgraduate Medical School, Beijing, 100853, China
| | - Ying Huang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Chang-Ting Liu
- Nanlou Respiratory Diseases Department, Chinese PLA General Hospital/Chinese PLA Postgraduate Medical School, Beijing, 100853, China.
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The adaptation of Escherichia coli cells grown in simulated microgravity for an extended period is both phenotypic and genomic. NPJ Microgravity 2017. [PMID: 28649637 PMCID: PMC5460176 DOI: 10.1038/s41526-017-0020-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Microorganisms impact spaceflight in a variety of ways. They play a positive role in biological systems, such as waste water treatment but can be problematic through buildups of biofilms that can affect advanced life support. Of special concern is the possibility that during extended missions, the microgravity environment will provide positive selection for undesirable genomic changes. Such changes could affect microbial antibiotic sensitivity and possibly pathogenicity. To evaluate this possibility, Escherichia coli (lac plus) cells were grown for over 1000 generations on Luria Broth medium under low-shear modeled microgravity conditions in a high aspect rotating vessel. This is the first study of its kind to grow bacteria for multiple generations over an extended period under low-shear modeled microgravity. Comparisons were made to a non-adaptive control strain using growth competitions. After 1000 generations, the final low-shear modeled microgravity-adapted strain readily outcompeted the unadapted lac minus strain. A portion of this advantage was maintained when the low-shear modeled microgravity strain was first grown in a shake flask environment for 10, 20, or 30 generations of growth. Genomic sequencing of the 1000 generation strain revealed 16 mutations. Of the five changes affecting codons, none were neutral. It is not clear how significant these mutations are as individual changes or as a group. It is concluded that part of the long-term adaptation to low-shear modeled microgravity is likely genomic. The strain was monitored for acquisition of antibiotic resistance by VITEK analysis throughout the adaptation period. Despite the evidence of genomic adaptation, resistance to a variety of antibiotics was never observed.
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Higginson EE, Galen JE, Levine MM, Tennant SM. Microgravity as a biological tool to examine host-pathogen interactions and to guide development of therapeutics and preventatives that target pathogenic bacteria. Pathog Dis 2016; 74:ftw095. [PMID: 27630185 DOI: 10.1093/femspd/ftw095] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/31/2016] [Indexed: 12/16/2022] Open
Abstract
Space exploration programs have long been interested in the effects of spaceflight on biology. This research is important not only in its relevance to future deep space exploration, but also because it has allowed investigators to ask questions about how gravity impacts cell behavior here on Earth. In the 1980s, scientists designed and built the first rotating wall vessel, capable of mimicking the low shear environment found in space. This vessel has since been used to investigate growth of both microorganisms and human tissue cells in low shear modeled microgravity conditions. Bacterial behavior has been shown to be altered both in space and under simulated microgravity conditions. In some cases, bacteria appear attenuated, whereas in others virulence is enhanced. This has consequences not only for manned spaceflight, but poses larger questions about the ability of bacteria to sense the world around them. By using the microgravity environment as a tool, we can exploit this phenomenon in the search for new therapeutics and preventatives against pathogenic bacteria for use both in space and on Earth.
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Affiliation(s)
- Ellen E Higginson
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - James E Galen
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Myron M Levine
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Sharon M Tennant
- Center for Vaccine Development and Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD 21201, USA Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Effects of simulated microgravity and spaceflight on morphological differentiation and secondary metabolism of Streptomyces coelicolor A3(2). Appl Microbiol Biotechnol 2015; 99:4409-22. [DOI: 10.1007/s00253-015-6386-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 12/31/2014] [Accepted: 01/05/2015] [Indexed: 02/07/2023]
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14
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Rosenzweig JA, Ahmed S, Eunson J, Chopra AK. Low-shear force associated with modeled microgravity and spaceflight does not similarly impact the virulence of notable bacterial pathogens. Appl Microbiol Biotechnol 2014; 98:8797-807. [PMID: 25149449 DOI: 10.1007/s00253-014-6025-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 08/06/2014] [Accepted: 08/08/2014] [Indexed: 12/18/2022]
Abstract
As their environments change, microbes experience various threats and stressors, and in the hypercompetitive microbial world, dynamism and the ability to rapidly respond to such changes allow microbes to outcompete their nutrient-seeking neighbors. Viewed in that light, the very difference between microbial life and death depends on effective stress response mechanisms. In addition to the more commonly studied temperature, nutritional, and chemical stressors, research has begun to characterize microbial responses to physical stress, namely low-shear stress. In fact, microbial responses to low-shear modeled microgravity (LSMMG), which emulates the microgravity experienced in space, have been studied quite widely in both prokaryotes and eukaryotes. Interestingly, LSMMG-induced changes in the virulence potential of several Gram-negative enteric bacteria, e.g., an increased enterotoxigenic Escherichia coli-mediated fluid secretion in ligated ileal loops of mice, an increased adherent invasive E. coli-mediated infectivity of Caco-2 cells, an increased Salmonella typhimurium-mediated invasion of both epithelial and macrophage cells, and S. typhimurium hypervirulence phenotype in BALB/c mice when infected by the intraperitoneal route. Although these were some examples where virulence of the bacteria was increased, there are instances where organisms became less virulent under LSMMG, e.g., hypovirulence of Yersinia pestis in cell culture infections and hypovirulence of methicillin-resistant Staphylococcus aureus, Enterococcus faecalis, and Listeria monocytogenes in a Caenorhabditis elegans infection model. In general, a number of LSMMG-exposed bacteria (but not all) seemed better equipped to handle subsequent stressors such as osmotic shock, acid shock, heat shock, and exposure to chemotherapeutics. This mini-review primarily discusses both LSMMG-induced as well as bona fide spaceflight-specific alterations in bacterial virulence potential, demonstrating that pathogens' responses to low-shear forces vary dramatically. Ultimately, a careful characterization of numerous bacterial pathogens' responses to low-shear forces is necessary to evaluate a more complete picture of how this physical stress impacts bacterial virulence since a "one-size-fits-all" response is clearly not the case.
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Affiliation(s)
- Jason A Rosenzweig
- Department of Biology and Center for Bionanotechnology and Environmental Research, Texas Southern University, 3100 Cleburne Street, Houston, TX, 77004, USA,
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Soni A, O'Sullivan L, Quick LN, Ott CM, Nickerson CA, Wilson JW. Conservation of the Low-shear Modeled Microgravity Response in Enterobacteriaceae and Analysis of the trp Genes in this Response. Open Microbiol J 2014; 8:51-8. [PMID: 25006354 PMCID: PMC4085587 DOI: 10.2174/1874285801408010051] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/19/2014] [Accepted: 04/03/2014] [Indexed: 11/22/2022] Open
Abstract
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.
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Affiliation(s)
- Anjali Soni
- Villanova University, Biology Department, 800 Lancaster Avenue, Villanova, PA 19085 ; Virginia Commonwealth University, School of Dentistry, Richmond, VA23298
| | - Laura O'Sullivan
- Villanova University, Biology Department, 800 Lancaster Avenue, Villanova, PA 19085 ; University of Pennsylvania,School of Veterinary Medicine, Philadelphia, PA 19104
| | - Laura N Quick
- Villanova University, Biology Department, 800 Lancaster Avenue, Villanova, PA 19085 ; Children's Hospital of Philadelphia, Philadelphia, PA 19104
| | - C Mark Ott
- NASA/Johnson Space Center, Habitability and Environmental Factors Division, Houston, TX77058
| | - Cheryl A Nickerson
- Arizona State University, Biodesign Institute, Center for Infectious Diseases and Vaccinology, Tempe, AZ85281
| | - James W Wilson
- Villanova University, Biology Department, 800 Lancaster Avenue, Villanova, PA 19085
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Deletion of Braun lipoprotein and plasminogen-activating protease-encoding genes attenuates Yersinia pestis in mouse models of bubonic and pneumonic plague. Infect Immun 2014; 82:2485-503. [PMID: 24686064 DOI: 10.1128/iai.01595-13] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Currently, there is no FDA-approved vaccine against Yersinia pestis, the causative agent of bubonic and pneumonic plague. Since both humoral immunity and cell-mediated immunity are essential in providing the host with protection against plague, we developed a live-attenuated vaccine strain by deleting the Braun lipoprotein (lpp) and plasminogen-activating protease (pla) genes from Y. pestis CO92. The Δlpp Δpla double isogenic mutant was highly attenuated in evoking both bubonic and pneumonic plague in a mouse model. Further, animals immunized with the mutant by either the intranasal or the subcutaneous route were significantly protected from developing subsequent pneumonic plague. In mice, the mutant poorly disseminated to peripheral organs and the production of proinflammatory cytokines concurrently decreased. Histopathologically, reduced damage to the lungs and livers of mice infected with the Δlpp Δpla double mutant compared to the level of damage in wild-type (WT) CO92-challenged animals was observed. The Δlpp Δpla mutant-immunized mice elicited a humoral immune response to the WT bacterium, as well as to CO92-specific antigens. Moreover, T cells from mutant-immunized animals exhibited significantly higher proliferative responses, when stimulated ex vivo with heat-killed WT CO92 antigens, than mice immunized with the same sublethal dose of WT CO92. Likewise, T cells from the mutant-immunized mice produced more gamma interferon (IFN-γ) and interleukin-4. These animals had an increasing number of tumor necrosis factor alpha (TNF-α)-producing CD4(+) and CD8(+) T cells than WT CO92-infected mice. These data emphasize the role of TNF-α and IFN-γ in protecting mice against pneumonic plague. Overall, our studies provide evidence that deletion of the lpp and pla genes acts synergistically in protecting animals against pneumonic plague, and we have demonstrated an immunological basis for this protection.
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Rosenzweig JA, Chopra AK. The exoribonuclease Polynucleotide Phosphorylase influences the virulence and stress responses of yersiniae and many other pathogens. Front Cell Infect Microbiol 2013; 3:81. [PMID: 24312901 PMCID: PMC3832800 DOI: 10.3389/fcimb.2013.00081] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 10/30/2013] [Indexed: 11/30/2022] Open
Abstract
Microbes are incessantly challenged by both biotic and abiotic stressors threatening their existence. Therefore, bacterial pathogens must possess mechanisms to successfully subvert host immune defenses as well as overcome the stress associated with host-cell encounters. To achieve this, bacterial pathogens typically experience a genetic re-programming whereby anti-host/stress factors become expressed and eventually translated into effector proteins. In that vein, the bacterial host-cell induced stress-response is similar to any other abiotic stress to which bacteria respond by up-regulating specific stress-responsive genes. Following the stress encounter, bacteria must degrade unnecessary stress responsive transcripts through RNA decay mechanisms. The three pathogenic yersiniae (Yersinia pestis, Y. pseudo-tuberculosis, and Y. enterocolitica) are all psychrotropic bacteria capable of growth at 4°C; however, cold growth is dependent on the presence of an exoribonuclease, polynucleotide phosphorylase (PNPase). PNPase has also been implicated as a virulence factor in several notable pathogens including the salmonellae, Helicobacter pylori, and the yersiniae [where it typically influences the type three secretion system (TTSS)]. Further, PNPase has been shown to associate with ribonuclease E (endoribonuclease), RhlB (RNA helicase), and enolase (glycolytic enzyme) in several Gram-negative bacteria forming a large, multi-protein complex known as the RNA degradosome. This review will highlight studies demonstrating the influence of PNPase on the virulence potentials and stress responses of various bacterial pathogens as well as focusing on the degradosome-dependent and -independent roles played by PNPase in yersiniae stress responses.
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Affiliation(s)
- Jason A Rosenzweig
- Department of Biology, Center for Bionanotechnology and Environmental Research, Texas Southern University Houston, TX, USA ; Department of Environmental and Interdisciplinary Sciences, Texas Southern University Houston, TX, USA
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