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Santiago-Martínez MG, Ferry JG. Methods for Culturing Anaerobic Microorganisms. Methods Mol Biol 2023; 2648:231-238. [PMID: 37039994 DOI: 10.1007/978-1-0716-3080-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
Anaerobic microorganisms (anaerobes) proliferate in diverse oxygen-free environments. They inhabit Earth's soils and aquatic sediments, the rumen and gut of mammals, and the gut of insects among many other oxygen-free environments. Anaerobes impact biotechnological, biomedical, ecological, and astrobiological fields. Sensitivity to oxygen is of prime consideration for successful culturing which is essential to understand function. Although cultivated for many years, the protocols and media components have been modified and adapted to the special needs of species, as well as conditions and variables for experimental evaluations. Here we describe a revised method used in our laboratories for the growth of methane-producing anaerobes (methanogenic archaea) which are among the most oxygen sensitive. The method is an example for the preparation of more specific media to cultivate a wide diversity of anaerobes.
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Affiliation(s)
- Michel Geovanni Santiago-Martínez
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA.
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA.
| | - James Gregory Ferry
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA
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2
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Siems K, Runzheimer K, Rehm A, Schwengers O, Heidler von Heilborn D, Kaser L, Arndt F, Neidhöfer C, Mengel JP, Parcina M, Lipski A, Hain T, Moeller R. Phenotypic and genomic assessment of the potential threat of human spaceflight-relevant Staphylococcus capitis isolates under stress conditions. Front Microbiol 2022; 13:1007143. [PMID: 36406458 PMCID: PMC9669719 DOI: 10.3389/fmicb.2022.1007143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 10/06/2022] [Indexed: 08/05/2023] Open
Abstract
Previous studies have reported that spaceflight specific conditions such as microgravity lead to changes in bacterial physiology and resistance behavior including increased expression of virulence factors, enhanced biofilm formation and decreased susceptibility to antibiotics. To assess if spaceflight induced physiological changes can manifest in human-associated bacteria, we compared three spaceflight relevant Staphylococcus capitis isolates (DSM 111179, ISS; DSM 31028, clean room; DSM 113836; artificial gravity bedrest study) with the type strain (DSM 20326T). We tested the three strains regarding growth, colony morphology, metabolism, fatty acid and polar lipid pattern, biofilm formation, susceptibility to antibiotics and survival in different stress conditions such as treatment with hydrogen peroxide, exposure to desiccation, and irradiation with X-rays and UV-C. Moreover, we sequenced, assembled, and analyzed the genomes of all four strains. Potential genetic determinants for phenotypic differences were investigated by comparative genomics. We found that all four strains show similar metabolic patterns and the same susceptibility to antibiotics. All four strains were considered resistant to fosfomycin. Physiological differences were mainly observed compared to the type strain and minor differences among the other three strains. The ISS isolate and the bedrest study isolate exhibit a strong delayed yellow pigmentation, which is absent in the other two strains. Pigments were extracted and analyzed by UV/Vis spectroscopy showing characteristic carotenoid spectra. The ISS isolate showed the highest growth rate as well as weighted average melting temperature (WAMT) of fatty acids (41.8°C) of all strains. The clean room isolate showed strongest biofilm formation and a high tolerance to desiccation. In general, all strains survived desiccation better in absence of oxygen. There were no differences among the strains regarding radiation tolerance. Phenotypic and genomic differences among the strains observed in this study are not inevitably indicating an increased virulence of the spaceflight isolate. However, the increased growth rate, higher WAMT and colony pigmentation of the spaceflight isolate are relevant phenotypes that require further research within the human spaceflight context. We conclude that combining genetic analysis with classical microbiological methods allows the detailed assessment of the potential threat of bacteria in highly regulated and extreme environments such as spaceflight environments.
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Affiliation(s)
- Katharina Siems
- Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Katharina Runzheimer
- Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Anna Rehm
- Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- Department of Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany
| | - Oliver Schwengers
- Department of Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany
| | - David Heidler von Heilborn
- Institute of Nutritional and Food Sciences, Food Microbiology and Hygiene, University of Bonn, Bonn, Germany
| | - Liv Kaser
- Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Franca Arndt
- Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- Institute for Medical Microbiology, Immunology and Hygiene, University Hospital of Cologne, Cologne, Germany
| | - Claudio Neidhöfer
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Jan Philipp Mengel
- Institute of Medical Microbiology, Justus Liebig University Giessen, Giessen, Germany
| | - Marijo Parcina
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - André Lipski
- Institute of Nutritional and Food Sciences, Food Microbiology and Hygiene, University of Bonn, Bonn, Germany
| | - Torsten Hain
- Institute of Medical Microbiology, Justus Liebig University Giessen, Giessen, Germany
- German Center for Infection Research (DZIF), Justus Liebig University Giessen, Partner Site Giessen-Marburg-Langen, Giessen, Germany
| | - Ralf Moeller
- Department of Radiation Biology, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
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3
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Wood JM, Singh NK, Guan L, Seuylemezian A, Benardini JN, Venkateswaran K. Performance of Multiple Metagenomics Pipelines in Understanding Microbial Diversity of a Low-Biomass Spacecraft Assembly Facility. Front Microbiol 2021; 12:685254. [PMID: 34650522 PMCID: PMC8508200 DOI: 10.3389/fmicb.2021.685254] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 08/27/2021] [Indexed: 11/24/2022] Open
Abstract
NASA planetary protection (PP) requires an assessment of the biological contamination of the potential microbial burden on spacecraft destined to explore planetary bodies that may harbor signs of life, like Mars and Europa. To help meet these goals, the performance of multiple metagenomic pipelines were compared and assessed for their ability to detect microbial diversity of a low-biomass clean room environment used to build spacecraft destined to these planetary bodies. Four vendors were chosen to implement their own metagenomic analysis pipeline on the shotgun sequences retrieved from environmental surfaces in the relevant environments at NASA's Jet Propulsion Laboratory. None of the vendors showed the same microbial profile patterns when analyzing same raw dataset since each vendor used different pipelines, which begs the question of the validity of a single pipeline to be recommended for future NASA missions. All four vendors detected species of interest, including spore-forming and extremotolerant bacteria, that have the potential to hitch-hike on spacecraft and contaminate the planetary bodies explored. Some vendors demonstrated through functional analysis of the metagenomes that the molecular mechanisms for spore-formation and extremotolerance were represented in the data. However, relative abundances of these microorganisms varied drastically between vendor analyses, questioning the ability of these pipelines to quantify the number of PP-relevant microorganisms on a spacecraft surface. Metagenomics offers tantalizing access to the genetic and functional potential of a microbial community that may offer NASA a viable method for microbial burden assays for planetary protection purposes. However, future development of technologies such as streamlining the processing of shotgun metagenome sequence data, long read sequencing, and all-inclusive larger curated and annotated microbial genome databases will be required to validate and translate relative abundances into an actionable assessment of PP-related microbes of interest. Additionally, the future development of machine learning and artificial intelligence techniques could help enhance the quality of these metagenomic analyses by providing more accurate identification of the genetic and functional potential of a microbial community.
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Affiliation(s)
| | | | | | | | | | - Kasthuri Venkateswaran
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
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4
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Godin PJ, Schuerger AC, Moores JE. Salt Tolerance and UV Protection of Bacillus subtilis and Enterococcus faecalis under Simulated Martian Conditions. ASTROBIOLOGY 2021; 21:394-404. [PMID: 33237800 DOI: 10.1089/ast.2020.2285] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ultraviolet (UV) irradiation on the surface of Mars is an important factor that affects the survivability of microorganisms on Mars. The possibility of martian brines made from Fe2(SO4)3, MnSO4, and MgSO4 salts providing a habitable niche on Mars via attenuation of UV radiation was investigated on the bacteria Bacillus subtilis and Enterococcus faecalis. Results demonstrate that it is possible for brines containing Fe2(SO4)3 on Mars to provide protection from harmful UV irradiation, even at concentrations as low as 0.5%. Brines made from MnSO4 and MgSO4 did not provide significant UV protection, and most spores/cells died over the course of short-term experiments. However, Fe2(SO4)3 brines are strongly acidic and thus were lethal to E. faecalis, when cells were exposed for 7 days. In contrast, B. subtilis, a spore-forming bacterium resistant to pH extremes, was unaffected by the acidic conditions of the brines and did not experience any significant lethal effects in Fe2(SO4)3. Any extant microbial life in martian Fe2(SO4)3 brines (if present) would need to be capable of surviving acidic environments, if these brines are to be considered a possible habitable niche. The results from this work are important to the search for life on planets with atmospheres that do not significantly attenuate UV radiation (i.e., like Mars) and to planetary protection, since it is possible that terrestrial bacteria in the genus Bacillus are likely to survive in Fe-sulfate brines on Mars.
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Affiliation(s)
- Paul J Godin
- Department of Earth and Space Science and Engineering, York University, Toronto, Canada
| | - Andrew C Schuerger
- Department of Plant Pathology, University of Florida, Space Life Sciences Lab, Merritt Island, Florida, USA
| | - John E Moores
- Department of Earth and Space Science and Engineering, York University, Toronto, Canada
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Schwendner P, Jobson ME, Schuerger AC. Addition of anaerobic electron acceptors to solid media did not enhance growth of 125 spacecraft bacteria under simulated low-pressure Martian conditions. Sci Rep 2020; 10:18290. [PMID: 33106561 PMCID: PMC7588431 DOI: 10.1038/s41598-020-75222-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 10/06/2020] [Indexed: 11/25/2022] Open
Abstract
To protect Mars from microbial contamination, research on growth of microorganisms found in spacecraft assembly clean rooms under simulated Martian conditions is required. This study investigated the effects of low atmospheric pressure on the growth of chemoorganotrophic spacecraft bacteria and whether the addition of Mars relevant anaerobic electron acceptors might enhance growth. The 125 bacteria screened here were recovered from actual Mars spacecraft. Growth at 7 hPa, 0 °C, and a CO2-enriched anoxic atmosphere (called low-PTA conditions) was tested on five TSA-based media supplemented with anaerobic electron acceptors. None of the 125 spacecraft bacteria showed active growth under the tested low-PTA conditions and amended media. In contrast, a decrease in viability was observed in most cases. Growth curves of two hypopiezotolerant strains, Serratia liquefaciens and Trichococcus pasteurii, were performed to quantify the effects of the added anaerobic electron acceptors. Slight variations in growth rates were determined for both bacteria. However, the final cell densities were similar for all media tested, indicating no general preference for any specific anaerobic electron acceptor. By demonstrating that a broad diversity of chemoorganotrophic and culturable spacecraft bacteria do not grow under the tested conditions, we conclude that there may be low risk of growth of chemoorganotrophic bacteria typically recovered from Mars spacecraft during planetary protection bioburden screenings.
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Affiliation(s)
- Petra Schwendner
- Space Life Sciences Lab, University of Florida, 505 Odyssey Way, Exploration Park, Merritt Island, FL, 32953, USA.
| | - Mary-Elizabeth Jobson
- Space Life Sciences Lab, University of Florida, 505 Odyssey Way, Exploration Park, Merritt Island, FL, 32953, USA
| | - Andrew C Schuerger
- Space Life Sciences Lab, University of Florida, 505 Odyssey Way, Exploration Park, Merritt Island, FL, 32953, USA
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6
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Habitability of Mars: How Welcoming Are the Surface and Subsurface to Life on the Red Planet? GEOSCIENCES 2019. [DOI: 10.3390/geosciences9090361] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mars is a planet of great interest in the search for signatures of past or present life beyond Earth. The years of research, and more advanced instrumentation, have yielded a lot of evidence which may be considered by the scientific community as proof of past or present habitability of Mars. Recent discoveries including seasonal methane releases and a subglacial lake are exciting, yet challenging findings. Concurrently, laboratory and environmental studies on the limits of microbial life in extreme environments on Earth broaden our knowledge of the possibility of Mars habitability. In this review, we aim to: (1) Discuss the characteristics of the Martian surface and subsurface that may be conducive to habitability either in the past or at present; (2) discuss laboratory-based studies on Earth that provide us with discoveries on the limits of life; and (3) summarize the current state of knowledge in terms of direction for future research.
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Rettberg P, Antunes A, Brucato J, Cabezas P, Collins G, Haddaji A, Kminek G, Leuko S, McKenna-Lawlor S, Moissl-Eichinger C, Fellous JL, Olsson-Francis K, Pearce D, Rabbow E, Royle S, Saunders M, Sephton M, Spry A, Walter N, Wimmer Schweingruber R, Treuet JC. Biological Contamination Prevention for Outer Solar System Moons of Astrobiological Interest: What Do We Need to Know? ASTROBIOLOGY 2019; 19:951-974. [PMID: 30762429 PMCID: PMC6767865 DOI: 10.1089/ast.2018.1996] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
To ensure that scientific investments in space exploration are not compromised by terrestrial contamination of celestial bodies, special care needs to be taken to preserve planetary conditions for future astrobiological exploration. Significant effort has been made and is being taken to address planetary protection in the context of inner Solar System exploration. In particular for missions to Mars, detailed internationally accepted guidelines have been established. For missions to the icy moons in the outer Solar System, Europa and Enceladus, the planetary protection requirements are so far based on a probabilistic approach and a conservative estimate of poorly known parameters. One objective of the European Commission-funded project, Planetary Protection of Outer Solar System, was to assess the existing planetary protection approach, to identify inherent knowledge gaps, and to recommend scientific investigations necessary to update the requirements for missions to the icy moons.
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Affiliation(s)
- Petra Rettberg
- Research Group Astrobiology, Radiation Biology Department, German Aerospace Center (DLR), Institute of Aerospace Medicine, Köln, Germany
- Address correspondence to: Petra Rettberg, German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology Department, Research Group Astrobiology, Linder Höhe, 51147 Köln, Germany
| | - André Antunes
- GEMM—Group for Extreme and Marine Microbiology, Department of Biology, Edge Hill University, Ormskirk, United Kingdom
| | - John Brucato
- Department of Physics and Astronomy, Astrophysical Observatory of Arcetri, National Institute for Astrophysics (INAF), Florence, Italy
| | - Patricia Cabezas
- Science Connect–European Science Foundation (ESF), Strasbourg, France
| | - Geoffrey Collins
- Department of Physics and Astronomy, Wheaton College, Massachusetts, Norton, Massachusetts
| | - Alissa Haddaji
- Committee on Space Research (COSPAR), Montpellier, France
| | - Gerhard Kminek
- Committee on Space Research (COSPAR), Montpellier, France
| | - Stefan Leuko
- Research Group Astrobiology, Radiation Biology Department, German Aerospace Center (DLR), Institute of Aerospace Medicine, Köln, Germany
| | | | | | - Jean-Louis Fellous
- Department of Physics and Astronomy, Wheaton College, Massachusetts, Norton, Massachusetts
| | - Karen Olsson-Francis
- Faculty of Science, Technology, Engineering & Mathematics, School of Environment, Earth & Ecosystem Sciences, The Open University, Milton Keynes, United Kingdom
| | - David Pearce
- Department of Applied Sciences, Northumbria University, Newcastle, United Kingdom
| | - Elke Rabbow
- Research Group Astrobiology, Radiation Biology Department, German Aerospace Center (DLR), Institute of Aerospace Medicine, Köln, Germany
| | - Samuel Royle
- Faculty of Engineering, Department of Earth Science & Engineering, Imperial College, London, United Kingdom
| | - Mark Saunders
- Independent Consultant for the US National Academies of Sciences (NAS), Washington, District of Columbia
| | - Mark Sephton
- Faculty of Engineering, Department of Earth Science & Engineering, Imperial College, London, United Kingdom
| | - Andy Spry
- Carl Sagan Center, SETI, Mountain View, California
| | - Nicolas Walter
- Science Connect–European Science Foundation (ESF), Strasbourg, France
| | - Robert Wimmer Schweingruber
- Institut für Experimentelle und Angewandte Physik, Abteilung Extraterrestrische Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
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Bak EN, Larsen MG, Jensen SK, Nørnberg P, Moeller R, Finster K. Wind-Driven Saltation: An Overlooked Challenge for Life on Mars. ASTROBIOLOGY 2019; 19:497-505. [PMID: 30407074 DOI: 10.1089/ast.2018.1856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Numerous studies have demonstrated that the martian surface environment is hostile to life because of its rough radiation climate and the reactive chemistry of the regolith. Physical processes such as erosion and transport of mineral particles by wind-driven saltation have hitherto not been considered as a life hazard. We report a series of experiments where bacterial endospores (spores of Bacillus subtilis) were exposed to a simulated saltating martian environment. We observed that 50% of the spores that are known to be highly resistant to radiation and oxidizing chemicals were destroyed by saltation-mediated abrasion within one minute. Scanning electron micrographs show that the spores were not only damaged by abrasion but were eradicated during the saltation process. We suggest that abrasion mediated by wind-driven saltation should be included as a factor that defines the habitability of the martian surface environment. The process may efficiently protect the martian surface from forward contamination with terrestrial microbial life-forms. Abrasion mediated by wind-driven saltation should also be considered as a major challenge to indigenous martian surface life if it exists/existed.
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Affiliation(s)
- E N Bak
- 1 Department of Bioscience, Aarhus University , Aarhus, Denmark
| | - M G Larsen
- 1 Department of Bioscience, Aarhus University , Aarhus, Denmark
| | - S K Jensen
- 2 Department of Chemistry, Aarhus University , Aarhus, Denmark
| | - P Nørnberg
- 1 Department of Bioscience, Aarhus University , Aarhus, Denmark
| | - R Moeller
- 3 Institute of Aerospace Medicine , Radiation Biology Department, Space Microbiology Research Group, German Aerospace Center (DLR e.V.), Cologne (Köln), Germany
| | - K Finster
- 1 Department of Bioscience, Aarhus University , Aarhus, Denmark
- 4 Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University , Aarhus, Denmark
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9
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Beblo-Vranesevic K, Bohmeier M, Perras AK, Schwendner P, Rabbow E, Moissl-Eichinger C, Cockell CS, Pukall R, Vannier P, Marteinsson VT, Monaghan EP, Ehrenfreund P, Garcia-Descalzo L, Gómez F, Malki M, Amils R, Gaboyer F, Westall F, Cabezas P, Walter N, Rettberg P. The responses of an anaerobic microorganism, Yersinia intermedia MASE-LG-1 to individual and combined simulated Martian stresses. PLoS One 2017; 12:e0185178. [PMID: 29069099 PMCID: PMC5656303 DOI: 10.1371/journal.pone.0185178] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 09/07/2017] [Indexed: 11/18/2022] Open
Abstract
The limits of life of aerobic microorganisms are well understood, but the responses of anaerobic microorganisms to individual and combined extreme stressors are less well known. Motivated by an interest in understanding the survivability of anaerobic microorganisms under Martian conditions, we investigated the responses of a new isolate, Yersinia intermedia MASE-LG-1 to individual and combined stresses associated with the Martian surface. This organism belongs to an adaptable and persistent genus of anaerobic microorganisms found in many environments worldwide. The effects of desiccation, low pressure, ionizing radiation, varying temperature, osmotic pressure, and oxidizing chemical compounds were investigated. The strain showed a high tolerance to desiccation, with a decline of survivability by four orders of magnitude during a storage time of 85 days. Exposure to X-rays resulted in dose-dependent inactivation for exposure up to 600 Gy while applied doses above 750 Gy led to complete inactivation. The effects of the combination of desiccation and irradiation were additive and the survivability was influenced by the order in which they were imposed. Ionizing irradiation and subsequent desiccation was more deleterious than vice versa. By contrast, the presence of perchlorates was not found to significantly affect the survival of the Yersinia strain after ionizing radiation. These data show that the organism has the capacity to survive and grow in physical and chemical stresses, imposed individually or in combination that are associated with Martian environment. Eventually it lost its viability showing that many of the most adaptable anaerobic organisms on Earth would be killed on Mars today.
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Affiliation(s)
- Kristina Beblo-Vranesevic
- Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
- * E-mail:
| | - Maria Bohmeier
- Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Alexandra K. Perras
- Department of Internal Medicine, Medical University of Graz, Graz, Austria
- Department of Microbiology and Archaea, University of Regensburg, Regensburg, Germany
| | - Petra Schwendner
- School of Physics and Astronomy, UK Center for Astrobiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Elke Rabbow
- Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - Christine Moissl-Eichinger
- Department of Internal Medicine, Medical University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
| | - Charles S. Cockell
- School of Physics and Astronomy, UK Center for Astrobiology, University of Edinburgh, Edinburgh, United Kingdom
| | - Rüdiger Pukall
- German Collection of Microorganisms and Cell Cultures, Leibniz Institute DSMZ, Braunschweig, Germany
| | | | - Viggo T. Marteinsson
- MATIS—Prokaria, Reykjavík, Iceland
- Faculty of Food Science and Nutrition, University of Iceland, Reykjavík, Iceland
| | | | - Pascale Ehrenfreund
- Leiden Observatory, Universiteit Leiden, Leiden, Netherland
- Space Policy Institute, George Washington University, Washington DC, United States of America
| | - Laura Garcia-Descalzo
- Instituto Nacional de Técnica Aeroespacial—Centro de Astrobiología (INTA-CAB), Madrid, Spain
| | - Felipe Gómez
- Instituto Nacional de Técnica Aeroespacial—Centro de Astrobiología (INTA-CAB), Madrid, Spain
| | | | | | - Frédéric Gaboyer
- Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique (CNRS), Orléans, France
| | - Frances Westall
- Centre de Biophysique Moléculaire, Centre National de la Recherche Scientifique (CNRS), Orléans, France
| | | | | | - Petra Rettberg
- Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
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10
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Mickol RL, Page JL, Schuerger AC. Magnesium Sulfate Salt Solutions and Ices Fail to Protect Serratia liquefaciens from the Biocidal Effects of UV Irradiation under Martian Conditions. ASTROBIOLOGY 2017; 17:401-412. [PMID: 28459604 DOI: 10.1089/ast.2015.1448] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The growth of Serratia liquefaciens has been demonstrated under martian conditions of 0.7 kPa (7 mbar), 0°C, and CO2-enriched anoxic atmospheres (Schuerger et al., 2013, Astrobiology 13:115-131), but studies into the survivability of cells under hypersaline conditions that are likely to be encountered on Mars are lacking. Serratia liquefaciens cells were suspended in aqueous MgSO4 solutions, or frozen brines, and exposed to terrestrial (i.e., 101.3 kPa, 24°C, O2/N2-normal atmosphere) or martian (i.e., 0.7 kPa, -25°C, CO2-anoxic atmosphere) conditions to assess the roles of MgSO4 and UV irradiation on the survival of S. liquefaciens. Four solutions were tested for their capability to attenuate martian UV irradiation in both liquid and frozen forms: sterile deionized water (SDIW), 10 mM PO4 buffer, 5% MgSO4, and 10% MgSO4. None of the solutions in either liquid or frozen forms provided enhanced protection against martian UV irradiation. Sixty minutes of UV irradiation reduced cell densities from 2.0 × 106 cells/mL to less than 10 cells/mL for both liquid and frozen solutions. In contrast, 3-4 mm of a Mars analog soil were sufficient to attenuate 100% of UV irradiation. Results suggest that terrestrial microorganisms may not survive on Sun-exposed surfaces on Mars, even if the cells are embedded in frozen martian brines composed of MgSO4. However, if dispersed microorganisms can be covered by only a few millimeters of dust or regolith, long-term survival is probable. Key Words: Hypobaria-Mars-Planetary protection-Brines. Astrobiology 17, 401-412.
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Affiliation(s)
- Rebecca L Mickol
- 1 Center for Space and Planetary Sciences, University of Arkansas , Fayetteville, Arkansas
| | - Jessica L Page
- 2 Department of Physics and Space Science, Florida Institute of Technology , Melbourne, Florida
| | - Andrew C Schuerger
- 3 Department of Plant Pathology, University of Florida , Gainesville, Florida
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11
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Karouia F, Peyvan K, Pohorille A. Toward biotechnology in space: High-throughput instruments for in situ biological research beyond Earth. Biotechnol Adv 2017; 35:905-932. [PMID: 28433608 DOI: 10.1016/j.biotechadv.2017.04.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 03/27/2017] [Accepted: 04/12/2017] [Indexed: 12/18/2022]
Abstract
Space biotechnology is a nascent field aimed at applying tools of modern biology to advance our goals in space exploration. These advances rely on our ability to exploit in situ high throughput techniques for amplification and sequencing DNA, and measuring levels of RNA transcripts, proteins and metabolites in a cell. These techniques, collectively known as "omics" techniques have already revolutionized terrestrial biology. A number of on-going efforts are aimed at developing instruments to carry out "omics" research in space, in particular on board the International Space Station and small satellites. For space applications these instruments require substantial and creative reengineering that includes automation, miniaturization and ensuring that the device is resistant to conditions in space and works independently of the direction of the gravity vector. Different paths taken to meet these requirements for different "omics" instruments are the subjects of this review. The advantages and disadvantages of these instruments and technological solutions and their level of readiness for deployment in space are discussed. Considering that effects of space environments on terrestrial organisms appear to be global, it is argued that high throughput instruments are essential to advance (1) biomedical and physiological studies to control and reduce space-related stressors on living systems, (2) application of biology to life support and in situ resource utilization, (3) planetary protection, and (4) basic research about the limits on life in space. It is also argued that carrying out measurements in situ provides considerable advantages over the traditional space biology paradigm that relies on post-flight data analysis.
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Affiliation(s)
- Fathi Karouia
- University of California San Francisco, Department of Pharmaceutical Chemistry, San Francisco, CA 94158, USA; NASA Ames Research Center, Exobiology Branch, MS239-4, Moffett Field, CA 94035, USA; NASA Ames Research Center, Flight Systems Implementation Branch, Moffett Field, CA 94035, USA.
| | | | - Andrew Pohorille
- University of California San Francisco, Department of Pharmaceutical Chemistry, San Francisco, CA 94158, USA; NASA Ames Research Center, Exobiology Branch, MS239-4, Moffett Field, CA 94035, USA.
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Reddy MPC, Saritha KV. Effects of the culture media optimization on pectinase production by Enterobacter sp. PSTB-1. 3 Biotech 2016; 6:207. [PMID: 28330278 PMCID: PMC5037110 DOI: 10.1007/s13205-016-0502-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2015] [Accepted: 08/18/2016] [Indexed: 11/30/2022] Open
Abstract
In the present study, media composition for high production of pectinase by Enterobacter sp. PSTB-1 in submerged fermentation was optimized using response surface methodology (RSM). Mango fruit processing industrial waste (MIW) was used as substrate (carbon source) as it contains high amount of pectin. Enterobacter sp. PSTB-1 used in present study has given pectin clear zone (PCZ) of 34 mm is higher than other isolates. The experimental results made by statistical design for high pectinase production revealed that the suitable media components: NaNO3 2.0 g/l, KCl 0.50 g/l, KH2PO4 1.0 g/l, MgSO4·7H2O 0.50 g/l, Yeast extract 1.0 g/l, mango industrial waste powder 5.0 g/l. The actual pectinase activity was 75.23 % correlated with the predicted pectinase activity where the model (CCD) was significant. Response surface modelling applied effectively to optimize the production of pectinase in submerged fermentation to make the process low cost-effective by using powdered mango industrial waste as substrate.
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Affiliation(s)
| | - K V Saritha
- Department of Biotechnology, Sri Venkateswara University, Tirupati, 517 502, India.
- Department of Future Studies, SVU College of Sciences, Sri Venkateswara University, Tirupati, 517 502, A.P., India.
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13
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Schuerger AC, Nicholson WL. Twenty Species of Hypobarophilic Bacteria Recovered from Diverse Soils Exhibit Growth under Simulated Martian Conditions at 0.7 kPa. ASTROBIOLOGY 2016; 16:964-976. [PMID: 27870556 DOI: 10.1089/ast.2016.1587] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Bacterial growth at low pressure is a new research area with implications for predicting microbial activity in clouds and the bulk atmosphere on Earth and for modeling the forward contamination of planetary surfaces like Mars. Here, we describe experiments on the recovery and identification of 20 species of bacterial hypobarophiles (def., growth under hypobaric conditions of approximately 1-2 kPa) in 10 genera capable of growth at 0.7 kPa. Hypobarophilic bacteria, but not archaea or fungi, were recovered from diverse soils, and high numbers of hypobarophiles were recovered from Arctic and Siberian permafrost soils. Isolates were identified through 16S rRNA sequencing to belong to the genera Bacillus, Carnobacterium, Clostridium, Cryobacterium, Exiguobacterium, Paenibacillus, Rhodococcus, Streptomyces, and Trichococcus. The highest population of culturable hypobarophilic bacteria (5.1 × 104 cfu/g) was recovered from Colour Lake soils from Axel Heiberg Island in the Canadian Arctic. In addition, we extend the number of hypobarophilic species in the genus Serratia to six type-strains that include S. ficaria, S. fonticola, S. grimesii, S. liquefaciens, S. plymuthica, and S. quinivorans. Microbial growth at 0.7 kPa suggests that pressure alone will not be growth-limiting on the martian surface, or in Earth's atmosphere up to an altitude of 34 km. Key Words: Barophile-Extremophilic microorganisms-Habitability-Mars-Special Region. Astrobiology 16, 964-976.
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Affiliation(s)
- Andrew C Schuerger
- 1 Department of Plant Pathology, University of Florida , Gainesville, Florida
| | - Wayne L Nicholson
- 2 Department of Microbiology and Cell Science, University of Florida , Gainesville, Florida
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Mora M, Mahnert A, Koskinen K, Pausan MR, Oberauner-Wappis L, Krause R, Perras AK, Gorkiewicz G, Berg G, Moissl-Eichinger C. Microorganisms in Confined Habitats: Microbial Monitoring and Control of Intensive Care Units, Operating Rooms, Cleanrooms and the International Space Station. Front Microbiol 2016; 7:1573. [PMID: 27790191 PMCID: PMC5061736 DOI: 10.3389/fmicb.2016.01573] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 09/20/2016] [Indexed: 01/15/2023] Open
Abstract
Indoor environments, where people spend most of their time, are characterized by a specific microbial community, the indoor microbiome. Most indoor environments are connected to the natural environment by high ventilation, but some habitats are more confined: intensive care units, operating rooms, cleanrooms and the international space station (ISS) are extraordinary living and working areas for humans, with a limited exchange with the environment. The purposes for confinement are different: a patient has to be protected from infections (intensive care unit, operating room), product quality has to be assured (cleanrooms), or confinement is necessary due to extreme, health-threatening outer conditions, as on the ISS. The ISS represents the most secluded man-made habitat, constantly inhabited by humans since November 2000 – and, inevitably, also by microorganisms. All of these man-made confined habitats need to be microbiologically monitored and controlled, by e.g., microbial cleaning and disinfection. However, these measures apply constant selective pressures, which support microbes with resistance capacities against antibiotics or chemical and physical stresses and thus facilitate the rise of survival specialists and multi-resistant strains. In this article, we summarize the available data on the microbiome of aforementioned confined habitats. By comparing the different operating, maintenance and monitoring procedures as well as microbial communities therein, we emphasize the importance to properly understand the effects of confinement on the microbial diversity, the possible risks represented by some of these microorganisms and by the evolution of (antibiotic) resistances in such environments – and the need to reassess the current hygiene standards.
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Affiliation(s)
- Maximilian Mora
- Department for Internal Medicine, Medical University of Graz, Graz Austria
| | - Alexander Mahnert
- Institute of Environmental Biotechnology, Graz University of Technology, Graz Austria
| | - Kaisa Koskinen
- Department for Internal Medicine, Medical University of Graz, GrazAustria; BioTechMed-Graz, GrazAustria
| | - Manuela R Pausan
- Department for Internal Medicine, Medical University of Graz, Graz Austria
| | | | - Robert Krause
- Department for Internal Medicine, Medical University of Graz, Graz Austria
| | - Alexandra K Perras
- Department for Internal Medicine, Medical University of Graz, GrazAustria; Department for Microbiology, University of Regensburg, RegensburgGermany
| | - Gregor Gorkiewicz
- BioTechMed-Graz, GrazAustria; Department of Pathology, Medical University of Graz, GrazAustria
| | - Gabriele Berg
- Institute of Environmental Biotechnology, Graz University of Technology, Graz Austria
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15
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Schuerger AC, Nicholson WL. Twenty-Three Species of Hypobarophilic Bacteria Recovered from Diverse Ecosystems Exhibit Growth under Simulated Martian Conditions at 0.7 kPa. ASTROBIOLOGY 2016; 16:335-47. [PMID: 27135839 PMCID: PMC4876496 DOI: 10.1089/ast.2015.1394] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
UNLABELLED Bacterial growth at low pressure is a new research area with implications for predicting microbial activity in clouds and the bulk atmosphere on Earth, and for modeling the forward contamination of planetary surfaces like Mars. Here, we describe experiments on the recovery and identification of 23 species of bacterial hypobarophiles (def., growth under hypobaric conditions of approximately 1-2 kPa) in 11 genera capable of growth at 0.7 kPa. Hypobarophilic bacteria, but not archaea or fungi, were recovered from soil and non-soil ecosystems. The highest numbers of hypobarophiles were recovered from Arctic soil, Siberian permafrost, and human saliva. Isolates were identified through 16S rRNA sequencing to belong to the genera Carnobacterium, Exiguobacterium, Leuconostoc, Paenibacillus, and Trichococcus. The highest population of culturable hypobarophilic bacteria (5.1 × 10(4) cfu/g) was recovered from Colour Lake soils from Axel Heiberg Island in the Canadian Arctic. In addition, we extend the number of hypobarophilic species in the genus Serratia to six type-strains that include S. ficaria, S. fonticola, S. grimesii, S. liquefaciens, S. plymuthica, and S. quinivorans. Microbial growth at 0.7 kPa suggests that pressure alone will not be growth-limiting on the martian surface or in Earth's atmosphere up to an altitude of 34 km. KEY WORDS Planetary protection-Simulated martian atmosphere-Piezophile-Habitability-Extremophilic microorganisms. Astrobiology 16, 335-347.
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Affiliation(s)
| | - Wayne L. Nicholson
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida
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16
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Weinmaier T, Probst AJ, La Duc MT, Ciobanu D, Cheng JF, Ivanova N, Rattei T, Vaishampayan P. A viability-linked metagenomic analysis of cleanroom environments: eukarya, prokaryotes, and viruses. MICROBIOME 2015; 3:62. [PMID: 26642878 PMCID: PMC4672508 DOI: 10.1186/s40168-015-0129-y] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 10/29/2015] [Indexed: 05/20/2023]
Abstract
BACKGROUND Recent studies posit a reciprocal dependency between the microbiomes associated with humans and indoor environments. However, none of these metagenome surveys has considered the viability of constituent microorganisms when inferring impact on human health. RESULTS Reported here are the results of a viability-linked metagenomics assay, which (1) unveil a remarkably complex community profile for bacteria, fungi, and viruses and (2) bolster the detection of underrepresented taxa by eliminating biases resulting from extraneous DNA. This approach enabled, for the first time ever, the elucidation of viral genomes from a cleanroom environment. Upon comparing the viable biomes and distribution of phylotypes within a cleanroom and adjoining (uncontrolled) gowning enclosure, the rigorous cleaning and stringent control countermeasures of the former were observed to select for a greater presence of anaerobes and spore-forming microflora. Sequence abundance and correlation analyses suggest that the viable indoor microbiome is influenced by both the human microbiome and the surrounding ecosystem(s). CONCLUSIONS The findings of this investigation constitute the literature's first ever account of the indoor metagenome derived from DNA originating solely from the potential viable microbial population. Results presented in this study should prove valuable to the conceptualization and experimental design of future studies on indoor microbiomes aimed at inferring impact on human health.
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Affiliation(s)
- Thomas Weinmaier
- Division of Computational Systems Biology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria.
| | - Alexander J Probst
- Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, USA.
| | - Myron T La Duc
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA.
- Precis Scientific, Scottsdale, AZ, USA.
| | | | | | | | - Thomas Rattei
- Division of Computational Systems Biology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria.
| | - Parag Vaishampayan
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA.
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Mahnert A, Vaishampayan P, Probst AJ, Auerbach A, Moissl-Eichinger C, Venkateswaran K, Berg G. Cleanroom Maintenance Significantly Reduces Abundance but Not Diversity of Indoor Microbiomes. PLoS One 2015; 10:e0134848. [PMID: 26273838 PMCID: PMC4537314 DOI: 10.1371/journal.pone.0134848] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 07/14/2015] [Indexed: 11/18/2022] Open
Abstract
Cleanrooms have been considered microbially-reduced environments and are used to protect human health and industrial product assembly. However, recent analyses have deciphered a rather broad diversity of microbes in cleanrooms, whose origin as well as physiological status has not been fully understood. Here, we examined the input of intact microbial cells from a surrounding built environment into a spacecraft assembly cleanroom by applying a molecular viability assay based on propidium monoazide (PMA). The controlled cleanroom (CCR) was characterized by ~6.2*103 16S rRNA gene copies of intact bacterial cells per m2 floor surface, which only represented 1% of the total community that could be captured via molecular assays without viability marker. This was in contrast to the uncontrolled adjoining facility (UAF) that had 12 times more living bacteria. Regarding diversity measures retrieved from 16S rRNA Illumina-tag analyzes, we observed, however, only a minor drop in the cleanroom facility allowing the conclusion that the number but not the diversity of microbes is strongly affected by cleaning procedures. Network analyses allowed tracking a substantial input of living microbes to the cleanroom and a potential enrichment of survival specialists like bacterial spore formers and archaeal halophiles and mesophiles. Moreover, the cleanroom harbored a unique community including 11 exclusive genera, e.g., Haloferax and Sporosarcina, which are herein suggested as indicators of cleanroom environments. In sum, our findings provide evidence that archaea are alive in cleanrooms and that cleaning efforts and cleanroom maintenance substantially decrease the number but not the diversity of indoor microbiomes.
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Affiliation(s)
- Alexander Mahnert
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, Pasadena, California, United States of America
| | - Parag Vaishampayan
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, Pasadena, California, United States of America
| | - Alexander J. Probst
- Department of Earth and Planetary Sciences, University of California, Berkeley, California, United States of America
| | - Anna Auerbach
- Institute for Microbiology and Archaea Center, University of Regensburg, Regensburg, Germany
| | - Christine Moissl-Eichinger
- Institute for Microbiology and Archaea Center, University of Regensburg, Regensburg, Germany
- Medical University Graz, Department of Internal Medicine, Graz, Austria
- BioTechMed Graz, Graz, Austria
| | - Kasthuri Venkateswaran
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, Pasadena, California, United States of America
| | - Gabriele Berg
- Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria
- * E-mail:
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18
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Probst AJ, Weinmaier T, DeSantis TZ, Santo Domingo JW, Ashbolt N. New perspectives on microbial community distortion after whole-genome amplification. PLoS One 2015; 10:e0124158. [PMID: 26010362 PMCID: PMC4444113 DOI: 10.1371/journal.pone.0124158] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 03/02/2015] [Indexed: 11/21/2022] Open
Abstract
Whole-genome amplification (WGA) has become an important tool to explore the genomic information of microorganisms in an environmental sample with limited biomass, however potential selective biases during the amplification processes are poorly understood. Here, we describe the effects of WGA on 31 different microbial communities from five biotopes that also included low-biomass samples from drinking water and groundwater. Our findings provide evidence that microbiome segregation by biotope was possible despite WGA treatment. Nevertheless, samples from different biotopes revealed different levels of distortion, with genomic GC content significantly correlated with WGA perturbation. Certain phylogenetic clades revealed a homogenous trend across various sample types, for instance Alpha- and Betaproteobacteria showed a decrease in their abundance after WGA treatment. On the other hand, Enterobacteriaceae, an important biomarker group for fecal contamination in groundwater and drinking water, were strongly affected by WGA treatment without a predictable pattern. These novel results describe the impact of WGA on low-biomass samples and may highlight issues to be aware of when designing future metagenomic studies that necessitate preceding WGA treatment.
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Affiliation(s)
- Alexander J. Probst
- Department for Bioinformatics, Second Genome Inc., South San Francisco, California, United States of America
| | - Thomas Weinmaier
- Department for Bioinformatics, Second Genome Inc., South San Francisco, California, United States of America
| | - Todd Z. DeSantis
- Department for Bioinformatics, Second Genome Inc., South San Francisco, California, United States of America
| | - Jorge W. Santo Domingo
- U.S. Environmental Protection Agency, Cincinnati, Ohio, United States of America
- * E-mail: (JWS); (NA)
| | - Nicholas Ashbolt
- U.S. Environmental Protection Agency, Cincinnati, Ohio, United States of America
- * E-mail: (JWS); (NA)
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19
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Kandil MM, Trigo C, Koskinen WC, Sadowsky MJ. Isolation and Characterization of a Novel Imidacloprid-Degrading Mycobacterium sp. Strain MK6 from an Egyptian Soil. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2015; 63:4721-7. [PMID: 25932751 DOI: 10.1021/acs.jafc.5b00754] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Thus far, only a small number and types of bacteria with limited ability in degrading imidacloprid have been reported. Also, genes regulating imidacloprid (IMDA) degradation have yet to be discovered. To study this in more detail, an enrichment technique was used to isolate consortia and pure cultures of IMDA-degrading bacteria. Through this approach, we successfully isolated a novel bacterium capable of completely degrading IMDA as a sole nitrogen source. The bacterium was subsequently identified as Mycobacterium sp. strain MK6 by sequence analysis of its 16S rRNA gene (Genbank accession number KR052814 ). BLASTn searches indicated that 16S rRNA gene from Mycobacterium sp. strain MK6 was 99% identical to several Mycobacterium spp. Mycobacterium sp. strain MK6 transformed 99.7% added IMDA (150 μg mL(-1)) in <2 weeks (t1/2 = 1.6 days) to 6-chloronicotinic acid (6-CNA) as its major metabolite. Although the isolated strain and mixed bacterial consortia were able to degrade IMDA, they failed to grow further on 6-CNA, indicating a lack of IMDA mineralization to carbon dioxide. Small amounts of the desnitro-olefin and desnitro-degradates of IMDA were observed during the incubation but did not accumulate in culture medium.
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Affiliation(s)
- Mahrous M Kandil
- †Department of Soil and Water, Faculty of Agriculture, Alexandria University, Alexandria 21545, Egypt
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20
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Derecho I, McCoy KB, Vaishampayan P, Venkateswaran K, Mogul R. Characterization of hydrogen peroxide-resistant Acinetobacter species isolated during the Mars Phoenix spacecraft assembly. ASTROBIOLOGY 2014; 14:837-847. [PMID: 25243569 DOI: 10.1089/ast.2014.1193] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The microbiological inventory of spacecraft and the associated assembly facility surfaces represent the primary pool of forward contaminants that may impact the integrity of life-detection missions. Herein, we report on the characterization of several strains of hydrogen peroxide-resistant Acinetobacter, which were isolated during the Mars Phoenix lander assembly. All Phoenix-associated Acinetobacter strains possessed very high catalase specific activities, and the specific strain, A. gyllenbergii 2P01AA, displayed a survival against hydrogen peroxide (no loss in 100 mM H2O2 for 1 h) that is perhaps the highest known among Gram-negative and non-spore-forming bacteria. Proteomic characterizations reveal a survival mechanism inclusive of proteins coupled to peroxide degradation (catalase and alkyl hydroperoxide reductase), energy/redox management (dihydrolipoamide dehydrogenase), protein synthesis/folding (EF-G, EF-Ts, peptidyl-tRNA hydrolase, DnaK), membrane functions (OmpA-like protein and ABC transporter-related protein), and nucleotide metabolism (HIT family hydrolase). Together, these survivability and biochemical parameters support the hypothesis that oxidative tolerance and the related biochemical features are the measurable phenotypes or outcomes for microbial survival in the spacecraft assembly facilities, where the low-humidity (desiccation) and clean (low-nutrient) conditions may serve as selective pressures. Hence, the spacecraft-associated Acinetobacter, due to the conferred oxidative tolerances, may ultimately hinder efforts to reduce spacecraft bioburden when using chemical sterilants, thus suggesting that non-spore-forming bacteria may need to be included in the bioburden accounting for future life-detection missions.
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Affiliation(s)
- I Derecho
- 1 California State Polytechnic University , Pomona, California
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21
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Kilmer BR, Eberl TC, Cunderla B, Chen F, Clark BC, Schneegurt MA. Molecular and Phenetic Characterization of the Bacterial Assemblage of Hot Lake, WA, an Environment with High Concentrations of Magnesium Sulfate, and Its Relevance to Mars. INTERNATIONAL JOURNAL OF ASTROBIOLOGY 2014; 13:69-80. [PMID: 24748851 PMCID: PMC3989109 DOI: 10.1017/s1473550413000268] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Hot Lake (Oroville, WA) is an athalassohaline epsomite lake that can have precipitating concentrations of MgSO4 salts, mainly epsomite. Little biotic study has been done on epsomite lakes and it was unclear whether microbes isolated from epsomite lakes and their margins would fall within recognized halotolerant genera, common soil genera, or novel phyla. Our initial study cultivated and characterized epsotolerant bacteria from the lake and its margins. Approximately 100 aerobic heterotrophic microbial isolates were obtained by repetitive streak-plating in high-salt media including either 10% NaCl or 2 M MgSO4. The collected isolates were all bacteria, nearly evenly divided between Gram-positive and Gram-negative clades, the most abundant genera being Halomonas, Idiomarina, Marinobacter, Marinococcus, Nesterenkonia, Nocardiopsis, and Planococcus. Bacillus, Corynebacterium, Exiguobacterium, Kocuria, and Staphylococcus also were cultured. This initial study included culture-independent community analysis of direct DNA extracts of lake margin soil using PCR-based clone libraries and 16S rRNA gene phylogeny. Clones assigned Gram-positive bacterial clades (70% of total clones) were dominated by sequences related to uncultured actinobacteria. There were abundant Deltaproteobacteria clones related to bacterial sulfur metabolisms and clones of Legionella and Coxiella. These epsomite lake microbial communities seem to be divided between bacteria primarily associated with hyperhaline environments rich in NaCl and salinotolerant relatives of common soil organisms. Archaea appear to be in low abundance and none were isolated, despite near-saturated salinities. Growth of microbes at very high concentrations of magnesium and other sulfates has relevance to planetary protection and life-detection missions to Mars, where scant liquid water may form as deliquescent brines and appear as eutectic liquids.
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Affiliation(s)
- Brian R. Kilmer
- Department of Biological Sciences, Wichita State University, Wichita, KS
| | - Timothy C. Eberl
- Department of Biological Sciences, Wichita State University, Wichita, KS
| | | | - Fei Chen
- Planetary Protection Group, Jet Propulsion Laboratory, NASA, Pasadena, CA
| | | | - Mark A. Schneegurt
- Department of Biological Sciences, Wichita State University, Wichita, KS
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22
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La Duc MT, Venkateswaran K, Conley CA. A genetic inventory of spacecraft and associated surfaces. ASTROBIOLOGY 2014; 14:15-23. [PMID: 24432775 DOI: 10.1089/ast.2013.0966] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Terrestrial organisms or other contaminants that are transported to Mars could interfere with efforts to study the potential for indigenous martian life. Similarly, contaminants that make the round-trip to Mars and back to Earth could compromise the ability to discriminate an authentic martian biosignature from a terrestrial organism. For this reason, it is important to develop a comprehensive inventory of microbes that are present on spacecraft to avoid interpreting their traces as authentic extraterrestrial biosignatures. Culture-based methods are currently used by NASA to assess spacecraft cleanliness but deliberately detect only a very small subset of total organisms present. The National Research Council has recommended that molecular (DNA)-based identification techniques should be developed as one aspect of managing the risk that terrestrial contamination could interfere with detection of life on (or returned from) Mars. The current understanding of the microbial diversity associated with spacecraft and clean room surfaces is expanding, but the capability to generate a comprehensive inventory of the microbial populations present on spacecraft outbound from Earth would address multiple considerations in planetary protection, relevant to both robotic and human missions. To this end, a 6-year genetic inventory study was undertaken by a NASA/JPL team. It was completed in 2012 and included delivery of a publicly available comprehensive final report. The genetic inventory study team evaluated the utility of three analytical technologies (conventional cloning techniques, PhyloChip DNA microarrays, and 454 tag-pyrosequencing) and combined them with a systematic methodology to collect, process, and archive nucleic acids as the first steps in assessing the phylogenetic breadth of microorganisms on spacecraft and associated surfaces.
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Affiliation(s)
- Myron T La Duc
- 1 Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California
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23
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Moissl-Eichinger C, Pukall R, Probst AJ, Stieglmeier M, Schwendner P, Mora M, Barczyk S, Bohmeier M, Rettberg P. Lessons learned from the microbial analysis of the Herschel spacecraft during assembly, integration, and test operations. ASTROBIOLOGY 2013; 13:1125-39. [PMID: 24313230 DOI: 10.1089/ast.2013.1024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Understanding microbial diversity in spacecraft assembly clean rooms is of major interest with respect to planetary protection considerations. A coordinated screening of different clean rooms in Europe and South America by three German institutes [Deutsches Zentrum für Luft- und Raumfahrt (DLR), Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ), and the Institute of Microbiology and Archaea Center, University of Regensburg] took place during the assembly, test, and launch operations of the Herschel spacecraft in 2006-2009. Through this campaign, we retrieved critical information regarding the microbiome within these clean rooms and on the Herschel spacecraft, which served as a model for upcoming ESA mission preparations. This "lessons learned" document summarizes and discusses the data we obtained during this sampling campaign. Additionally, we have taken the opportunity to create a database that includes all 16S rRNA gene sequences ever retrieved from molecular and cultivable diversity studies of spacecraft assembly clean rooms to compare the microbiomes of US, European, and South American facilities.
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Schwendner P, Moissl-Eichinger C, Barczyk S, Bohmeier M, Pukall R, Rettberg P. Insights into the microbial diversity and bioburden in a South American spacecraft assembly clean room. ASTROBIOLOGY 2013; 13:1140-54. [PMID: 24341458 DOI: 10.1089/ast.2013.1023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In this study, samples from the spacecraft assembly clean room BAF (final assembly building), located at Centre Spatial Guyanais in Kourou, French Guiana, were characterized by qualitative and quantitative methods to determine the bioburden and biodiversity. The cultivation assays mainly focused on extremotolerant microorganisms that have special metabolic skills, such as the ability to grow without oxygen, fix nitrogen, grow autotrophically, or reduce sulfate. A broad range of media and growth conditions were used to simulate possible extraterrestrial environments and clean room buildings. In addition to these alternative cultivation assays, the ESA standard protocol for bioburden estimation was also applied. The phylogenetic analysis of the isolates (mainly facultative anaerobes) showed an extraordinarily broad cultivable biodiversity. Overall, 49 species were isolated and identified as members of the bacterial phyla Actinobacteria, Firmicutes, α-, β-, γ-Proteobacteria, and Bacteroidetes/Chlorobi. In addition to cultivation-based analyses, molecular techniques were also applied, including construction of a 16S rRNA gene clone library. The results indicate a wide-ranging microbial diversity (12 bacterial phyla, 34 families) that not only confirms the results of the cultivation efforts but also deepens our understanding of the noncultivable variety. Our investigations hint at a very broad, mainly uncultivated microbial diversity.
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Affiliation(s)
- Petra Schwendner
- 1 Institute of Microbiology and Archaea Center, University of Regensburg , Regensburg, Germany
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25
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Zhang M, Powell CA, Benyon LS, Zhou H, Duan Y. Deciphering the bacterial microbiome of citrus plants in response to 'Candidatus Liberibacter asiaticus'-infection and antibiotic treatments. PLoS One 2013; 8:e76331. [PMID: 24250784 PMCID: PMC3826729 DOI: 10.1371/journal.pone.0076331] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 08/23/2013] [Indexed: 11/18/2022] Open
Abstract
The bacterial microbiomes of citrus plants were characterized in response to 'Candidatus Liberibacter asiaticus' (Las)-infection and treatments with ampicillin (Amp) and gentamicin (Gm) by Phylochip-based metagenomics. The results revealed that 7,407 of over 50,000 known Operational Taxonomic Units (OTUs) in 53 phyla were detected in citrus leaf midribs using the PhyloChip™ G3 array, of which five phyla were dominant, Proteobacteria (38.7%), Firmicutes (29.0%), Actinobacteria (16.1%), Bacteroidetes (6.2%) and Cyanobacteria (2.3%). The OTU62806, representing 'Candidatus Liberibacter', was present with a high titer in the plants graft-inoculated with Las-infected scions treated with Gm at 100 mg/L and in the water-treated control (CK1). However, the Las bacterium was not detected in the plants graft-inoculated with Las-infected scions treated with Amp at 1.0 g/L or in plants graft-inoculated with Las-free scions (CK2). The PhyloChip array demonstrated that more OTUs, at a higher abundance, were detected in the Gm-treated plants than in the other treatment and the controls. Pairwise comparisons indicated that 23 OTUs from the Achromobacter spp. and 12 OTUs from the Methylobacterium spp. were more abundant in CK2 and CK1, respectively. Ten abundant OTUs from the Stenotrophomonas spp. were detected only in the Amp-treatment. These results provide new insights into microbial communities that may be associated with the progression of citrus huanglongbing (HLB) and the potential effects of antibiotics on the disease and microbial ecology.
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Affiliation(s)
- Muqing Zhang
- Indian River Research and Education Center, IFAS-UF, Fort Pierce, Florida, United States of America
- USDA-ARS, US Horticultural Lab, Fort Pierce, Florida, United States of America
- State Key Lab for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning, Guangxi, China
| | - Charles A. Powell
- Indian River Research and Education Center, IFAS-UF, Fort Pierce, Florida, United States of America
| | - Lesley S. Benyon
- USDA-ARS, US Horticultural Lab, Fort Pierce, Florida, United States of America
| | - Hui Zhou
- State Key Lab for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, Nanning, Guangxi, China
| | - Yongping Duan
- USDA-ARS, US Horticultural Lab, Fort Pierce, Florida, United States of America
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Schuerger AC, Ulrich R, Berry BJ, Nicholson WL. Growth of Serratia liquefaciens under 7 mbar, 0°C, and CO2-enriched anoxic atmospheres. ASTROBIOLOGY 2013; 13:115-31. [PMID: 23289858 PMCID: PMC3582281 DOI: 10.1089/ast.2011.0811] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Accepted: 11/28/2012] [Indexed: 05/21/2023]
Abstract
Twenty-six strains of 22 bacterial species were tested for growth on trypticase soy agar (TSA) or sea-salt agar (SSA) under hypobaric, psychrophilic, and anoxic conditions applied singly or in combination. As each factor was added to multi-parameter assays, the interactive stresses decreased the numbers of strains capable of growth and, in general, reduced the vigor of the strains observed to grow. Only Serratia liquefaciens strain ATCC 27592 exhibited growth at 7 mbar, 0°C, and CO2-enriched anoxic atmospheres. To discriminate between the effects of desiccation and hypobaria, vegetative cells of Bacillus subtilis strain 168 and Escherichia coli strain K12 were grown on TSA surfaces and simultaneously in liquid Luria-Bertani (LB) broth media. Inhibition of growth under hypobaria for 168 and K12 decreased in similar ways for both TSA and LB assays as pressures were reduced from 100 to 25 mbar. Results for 168 and K12 on TSA and LB are interpreted to indicate a direct low-pressure effect on microbial growth with both species and do not support the hypothesis that desiccation alone on TSA was the cause of reduced growth at low pressures. The growth of S. liquefaciens at 7 mbar, 0°C, and CO2-enriched anoxic atmospheres was surprising since S. liquefaciens is ecologically a generalist that occurs in terrestrial plant, fish, animal, and food niches. In contrast, two extremophiles tested in the assays, Deinococcus radiodurans strain R1 and Psychrobacter cryohalolentis strain K5, failed to grow under hypobaric (25 mbar; R1 only), psychrophilic (0°C; R1 only), or anoxic (< 0.1% ppO2; both species) conditions.
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Affiliation(s)
- Andrew C Schuerger
- Department of Plant Pathology, University of Florida , Space Life Sciences Lab, Kennedy Space Center, Florida 32899, USA.
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Vaishampayan P, Probst AJ, La Duc MT, Bargoma E, Benardini JN, Andersen GL, Venkateswaran K. New perspectives on viable microbial communities in low-biomass cleanroom environments. ISME JOURNAL 2012; 7:312-24. [PMID: 23051695 DOI: 10.1038/ismej.2012.114] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The advent of phylogenetic DNA microarrays and high-throughput pyrosequencing technologies has dramatically increased the resolution and accuracy of detection of distinct microbial lineages in mixed microbial assemblages. Despite an expanding array of approaches for detecting microbes in a given sample, rapid and robust means of assessing the differential viability of these cells, as a function of phylogenetic lineage, remain elusive. In this study, pre-PCR propidium monoazide (PMA) treatment was coupled with downstream pyrosequencing and PhyloChip DNA microarray analyses to better understand the frequency, diversity and distribution of viable bacteria in spacecraft assembly cleanrooms. Sample fractions not treated with PMA, which were indicative of the presence of both live and dead cells, yielded a great abundance of highly diverse bacterial pyrosequences. In contrast, only 1% to 10% of all of the pyrosequencing reads, arising from a few robust bacterial lineages, originated from sample fractions that had been pre-treated with PMA. The results of PhyloChip analyses of PMA-treated and -untreated sample fractions were in agreement with those of pyrosequencing. The viable bacterial population detected in cleanrooms devoid of spacecraft hardware was far more diverse than that observed in cleanrooms that housed mission-critical spacecraft hardware. The latter was dominated by hardy, robust organisms previously reported to survive in oligotrophic cleanroom environments. Presented here are the findings of the first ever comprehensive effort to assess the viability of cells in low-biomass environmental samples, and correlate differential viability with phylogenetic affiliation.
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Affiliation(s)
- Parag Vaishampayan
- Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
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Ralebitso-Senior TK, Senior E, Di Felice R, Jarvis K. Waste gas biofiltration: advances and limitations of current approaches in microbiology. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:8542-8573. [PMID: 22746978 DOI: 10.1021/es203906c] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
As confidence in gas biofiltration efficacy grows, ever more complex malodorant and toxic molecules are ameliorated. In parallel, for many countries, emission control legislation becomes increasingly stringent to accommodate both public health and climate change imperatives. Effective gas biofiltration in biofilters and biotrickling filters depends on three key bioreactor variables: the support medium; gas molecule solubilization; and the catabolic population. Organic and inorganic support media, singly or in combination, have been employed and their key criteria are considered by critical appraisal of one, char. Catabolic species have included fungal and bacterial monocultures and, to a lesser extent, microbial communities. In the absence of organic support medium (soil, compost, sewage sludge, etc.) inoculum provision, a targeted enrichment and isolation program must be undertaken followed, possibly, by culture efficacy improvement. Microbial community process enhancement can then be gained by comprehensive characterization of the culturable and total populations. For all species, support medium attachment is critical and this is considered prior to filtration optimization by water content, pH, temperature, loadings, and nutrients manipulation. Finally, to negate discharge of fungal spores, and/or archaeal and/or bacterial cells, capture/destruction technologies are required to enable exploitation of the mineralization product CO(2).
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29
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Stieglmeier M, Rettberg P, Barczyk S, Bohmeier M, Pukall R, Wirth R, Moissl-Eichinger C. Abundance and diversity of microbial inhabitants in European spacecraft-associated clean rooms. ASTROBIOLOGY 2012; 12:572-85. [PMID: 22794299 DOI: 10.1089/ast.2011.0735] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The determination of the microbial load of a spacecraft en route to interesting extraterrestrial environments is mandatory and currently based on the culturable, heat-shock-surviving portion of microbial contaminants. Our study compared these classical bioburden measurements as required by NASA's and ESA's guidelines for the microbial examination of flight hardware, with molecular analysis methods (16S rRNA gene cloning and quantitative PCR) to further develop our understanding of the diversity and abundance of the microbial communities of spacecraft-associated clean rooms. Three samplings of the Herschel Space Observatory and its surrounding clean rooms were performed in two different European facilities. Molecular analyses detected a broad diversity of microbes typically found in the human microbiome with three bacterial genera (Staphylococcus, Propionibacterium, and Brevundimonas) common to all three locations. Bioburden measurements revealed a low, but heterogeneous, abundance of spore-forming and other heat-resistant microorganisms. Total cell numbers estimated by quantitative real-time PCR were typically 3 orders of magnitude greater than those determined by viable counts, which indicates a tendency for traditional methods to underestimate the extent of clean room bioburden. Furthermore, the molecular methods allowed the detection of a much broader diversity than traditional culture-based methods.
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30
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Cooper M, La Duc MT, Probst A, Vaishampayan P, Stam C, Benardini JN, Piceno YM, Andersen GL, Venkateswaran K. Comparison of innovative molecular approaches and standard spore assays for assessment of surface cleanliness. Appl Environ Microbiol 2011; 77:5438-44. [PMID: 21652744 PMCID: PMC3147454 DOI: 10.1128/aem.00192-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Accepted: 05/28/2011] [Indexed: 11/20/2022] Open
Abstract
A bacterial spore assay and a molecular DNA microarray method were compared for their ability to assess relative cleanliness in the context of bacterial abundance and diversity on spacecraft surfaces. Colony counts derived from the NASA standard spore assay were extremely low for spacecraft surfaces. However, the PhyloChip generation 3 (G3) DNA microarray resolved the genetic signatures of a highly diverse suite of microorganisms in the very same sample set. Samples completely devoid of cultivable spores were shown to harbor the DNA of more than 100 distinct microbial phylotypes. Furthermore, samples with higher numbers of cultivable spores did not necessarily give rise to a greater microbial diversity upon analysis with the DNA microarray. The findings of this study clearly demonstrated that there is not a statistically significant correlation between the cultivable spore counts obtained from a sample and the degree of bacterial diversity present. Based on these results, it can be stated that validated state-of-the-art molecular techniques, such as DNA microarrays, can be utilized in parallel with classical culture-based methods to further describe the cleanliness of spacecraft surfaces.
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Affiliation(s)
- Moogega Cooper
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
| | - Myron T. La Duc
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
| | - Alexander Probst
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
| | - Parag Vaishampayan
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
| | - Christina Stam
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
| | - James N. Benardini
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
| | - Yvette M. Piceno
- Lawrence Berkeley National Laboratory, MS 70A-3317, One Cyclotron Rd., Berkeley, California 94720
| | - Gary L. Andersen
- Lawrence Berkeley National Laboratory, MS 70A-3317, One Cyclotron Rd., Berkeley, California 94720
| | - Kasthuri Venkateswaran
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109
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Evaluation of procedures for the collection, processing, and analysis of biomolecules from low-biomass surfaces. Appl Environ Microbiol 2011; 77:2943-53. [PMID: 21398492 DOI: 10.1128/aem.02978-10] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To comprehensively assess microbial diversity and abundance via molecular-analysis-based methods, procedures for sample collection, processing, and analysis were evaluated in depth. A model microbial community (MMC) of known composition, representative of a typical low-biomass surface sample, was used to examine the effects of variables in sampling matrices, target cell density/molecule concentration, and cryogenic storage on the overall efficacy of the sampling regimen. The MMC used in this study comprised 11 distinct species of bacterial, archaeal, and fungal lineages associated with either spacecraft or clean-room surfaces. A known cellular density of MMC was deposited onto stainless steel coupons, and after drying, a variety of sampling devices were used to recover cells and biomolecules. The biomolecules and cells/spores recovered from each collection device were assessed by cultivable and microscopic enumeration, and quantitative and species-specific PCR assays. rRNA gene-based quantitative PCR analysis showed that cotton swabs were superior to nylon-flocked swabs for sampling of small surface areas, and for larger surfaces, biological sampling kits significantly outperformed polyester wipes. Species-specific PCR revealed differential recovery of certain species dependent upon the sampling device employed. The results of this study empower current and future molecular-analysis-based microbial sampling and processing methodologies.
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Recovery of bacillus spore contaminants from rough surfaces: a challenge to space mission cleanliness control. Appl Environ Microbiol 2011; 77:1628-37. [PMID: 21216908 DOI: 10.1128/aem.02037-10] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microbial contaminants on spacecraft can threaten the scientific integrity of space missions due to probable interference with life detection experiments. Therefore, space agencies measure the cultivable spore load ("bioburden") of a spacecraft. A recent study has reported an insufficient recovery of Bacillus atrophaeus spores from Vectran fabric, a typical spacecraft airbag material (A. Probst, R. Facius, R. Wirth, and C. Moissl-Eichinger, Appl. Environ. Microbiol. 76:5148-5158, 2010). Here, 10 different sampling methods were compared for B. atrophaeus spore recovery from this rough textile, revealing significantly different efficiencies (0.5 to 15.4%). The most efficient method, based on the wipe-rinse technique (foam-spatula protocol; 13.2% efficiency), was then compared to the current European Space Agency (ESA) standard wipe assay in sampling four different kinds of spacecraft-related surfaces. Results indicate that the novel protocol out-performed the standard method with an average efficiency of 41.1% compared to 13.9% for the standard method. Additional experiments were performed by sampling Vectran fabric seeded with seven different spore concentrations and five different Bacillus species (B. atrophaeus, B. anthracis Sterne, B. megaterium, B. thuringiensis, and B. safensis). Among these, B. atrophaeus spores were recovered with the highest (13.2%) efficiency and B. anthracis Sterne spores were recovered with the lowest (0.3%) efficiency. Different inoculation methods of seeding spores on test surfaces (spotting and aerosolization) resulted in different spore recovery efficiencies. The results of this study provide a step forward in understanding the spore distribution on and recovery from rough surfaces. The results presented will contribute relevant knowledge to the fields of astrobiology and B. anthracis research.
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Lin WT, Luo JF, Guo Y. Comparison and Characterization of Microbial Communities in Sulfide-rich Wastewater with and without Propidium Monoazide Treatment. Curr Microbiol 2010; 62:374-81. [DOI: 10.1007/s00284-010-9716-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 07/07/2010] [Indexed: 10/19/2022]
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Validation of a nylon-flocked-swab protocol for efficient recovery of bacterial spores from smooth and rough surfaces. Appl Environ Microbiol 2010; 76:5148-58. [PMID: 20543054 DOI: 10.1128/aem.00399-10] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In order to meet planetary-protection requirements, culturable bacterial spore loads are measured representatively for the total microbial contamination of spacecraft. However, the National Aeronautics and Space Administration's (NASA's) cotton swab protocols for spore load determination have not changed for decades. To determine whether a more efficient alternative was available, a novel swab was evaluated for recovery of different Bacillus atrophaeus spore concentrations on stainless steel and other surfaces. Two protocols for the nylon-flocked swab (NFS) were validated and compared to the present NASA standard protocol. The results indicate that the novel swab protocols recover 3- to 4-fold more (45.4% and 49.0% recovery efficiency) B. atrophaeus spores than the NASA standard method (13.2%). Moreover, the nylon-flocked-swab protocols were superior in recovery efficiency for spores of seven different Bacillus species, including Bacillus anthracis Sterne (recovery efficiency, 20%). The recovery efficiencies for B. atrophaeus spores from different surfaces showed a variation from 5.9 to 62.0%, depending on the roughness of the surface analyzed. Direct inoculation of the swab resulted in a recovery rate of about 80%, consistent with the results of scanning electron micrographs that allowed detailed comparisons of the two swab types. The results of this investigation will significantly contribute to the cleanliness control of future life detection missions and will provide significant improvement in detection of B. anthracis contamination for law enforcement and security efforts.
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