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Veloso M, Waldisperg A, Arros P, Berríos-Pastén C, Acosta J, Colque H, Varas MA, Allende ML, Orellana LH, Marcoleta AE. Diversity, Taxonomic Novelty, and Encoded Functions of Salar de Ascotán Microbiota, as Revealed by Metagenome-Assembled Genomes. Microorganisms 2023; 11:2819. [PMID: 38004830 PMCID: PMC10673233 DOI: 10.3390/microorganisms11112819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/12/2023] [Accepted: 11/15/2023] [Indexed: 11/26/2023] Open
Abstract
Salar de Ascotán is a high-altitude arsenic-rich salt flat exposed to high ultraviolet radiation in the Atacama Desert, Chile. It hosts unique endemic flora and fauna and is an essential habitat for migratory birds, making it an important site for conservation and protection. However, there is limited information on the resident microbiota's diversity, genomic features, metabolic potential, and molecular mechanisms that enable it to thrive in this extreme environment. We used long- and short-read metagenomics to investigate the microbial communities in Ascotán's water, sediment, and soil. Bacteria predominated, mainly Pseudomonadota, Acidobacteriota, and Bacteroidota, with a remarkable diversity of archaea in the soil. Following hybrid assembly, we recovered high-quality bacterial (101) and archaeal (6) metagenome-assembled genomes (MAGs), including representatives of two putative novel families of Patescibacteria and Pseudomonadota and two novel orders from the archaeal classes Halobacteriota and Thermoplasmata. We found different metabolic capabilities across distinct lineages and a widespread presence of genes related to stress response, DNA repair, and resistance to arsenic and other metals. These results highlight the remarkable diversity and taxonomic novelty of the Salar de Ascotán microbiota and its rich functional repertoire, making it able to resist different harsh conditions. The highly complete MAGs described here could serve future studies and bioprospection efforts focused on salt flat extremophiles, and contribute to enriching databases with microbial genome data from underrepresented regions of our planet.
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Affiliation(s)
- Marcelo Veloso
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile; (M.V.); (A.W.); (P.A.); (C.B.-P.); (J.A.); (H.C.); (M.A.V.)
| | - Angie Waldisperg
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile; (M.V.); (A.W.); (P.A.); (C.B.-P.); (J.A.); (H.C.); (M.A.V.)
| | - Patricio Arros
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile; (M.V.); (A.W.); (P.A.); (C.B.-P.); (J.A.); (H.C.); (M.A.V.)
| | - Camilo Berríos-Pastén
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile; (M.V.); (A.W.); (P.A.); (C.B.-P.); (J.A.); (H.C.); (M.A.V.)
| | - Joaquín Acosta
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile; (M.V.); (A.W.); (P.A.); (C.B.-P.); (J.A.); (H.C.); (M.A.V.)
| | - Hazajem Colque
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile; (M.V.); (A.W.); (P.A.); (C.B.-P.); (J.A.); (H.C.); (M.A.V.)
| | - Macarena A. Varas
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile; (M.V.); (A.W.); (P.A.); (C.B.-P.); (J.A.); (H.C.); (M.A.V.)
- Millenium Institute Center for Genome Regulation, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile;
| | - Miguel L. Allende
- Millenium Institute Center for Genome Regulation, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile;
| | - Luis H. Orellana
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Celsiusstr. 1, D-28359 Bremen, Germany;
| | - Andrés E. Marcoleta
- Grupo de Microbiología Integrativa, Laboratorio de Biología Estructural y Molecular BEM, Faculty of Science, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago 7800003, Chile; (M.V.); (A.W.); (P.A.); (C.B.-P.); (J.A.); (H.C.); (M.A.V.)
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Wu JH, McGenity TJ, Rettberg P, Simões MF, Li WJ, Antunes A. The archaeal class Halobacteria and astrobiology: Knowledge gaps and research opportunities. Front Microbiol 2022; 13:1023625. [PMID: 36312929 PMCID: PMC9608585 DOI: 10.3389/fmicb.2022.1023625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 09/07/2022] [Indexed: 09/19/2023] Open
Abstract
Water bodies on Mars and the icy moons of the outer solar system are now recognized as likely being associated with high levels of salt. Therefore, the study of high salinity environments and their inhabitants has become increasingly relevant for Astrobiology. Members of the archaeal class Halobacteria are the most successful microbial group living in hypersaline conditions and are recognized as key model organisms for exposure experiments. Despite this, data for the class is uneven across taxa and widely dispersed across the literature, which has made it difficult to properly assess the potential for species of Halobacteria to survive under the polyextreme conditions found beyond Earth. Here we provide an overview of published data on astrobiology-linked exposure experiments performed with members of the Halobacteria, identifying clear knowledge gaps and research opportunities.
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Affiliation(s)
- Jia-Hui Wu
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Taipa, Macau SAR, China
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Taipa, Macau SAR, China
| | - Terry J. McGenity
- School of Life Sciences, University of Essex, Colchester, United Kingdom
| | - Petra Rettberg
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Köln, Germany
| | - Marta F. Simões
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Taipa, Macau SAR, China
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Taipa, Macau SAR, China
| | - Wen-Jun Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - André Antunes
- State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology (MUST), Taipa, Macau SAR, China
- China National Space Administration (CNSA), Macau Center for Space Exploration and Science, Taipa, Macau SAR, China
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3
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Marasini S, Leanse LG, Dai T. Can microorganisms develop resistance against light based anti-infective agents? Adv Drug Deliv Rev 2021; 175:113822. [PMID: 34089778 DOI: 10.1016/j.addr.2021.05.032] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/25/2021] [Accepted: 05/31/2021] [Indexed: 12/13/2022]
Abstract
Recently, there have been increasing numbers of publications illustrating the potential of light-based antimicrobial therapies to combat antimicrobial resistance. Several modalities, in particular, which have proven antimicrobial efficacy against a wide range of pathogenic microbes include: photodynamic therapy (PDT), ultraviolet light (UVA, UVB and UVC), and antimicrobial blue light (aBL). Using these techniques, microbial cells can be inactivated rapidly, either by inducing reactive oxygen species that are deleterious to the microbial cells (PDT, aBL and UVA) or by causing irreversible DNA damage via direct absorption (UVB and UVC). Given the multi-targeted nature of light-based antimicrobial modalities, it has been hypothesised that resistance development to these approaches is highly unlikely. Furthermore, with the exception of a small number of studies, it has been found that resistance to light based anti-infective agents appears unlikely, irrespective of the modality in question. The concurrent literature however stipulates, that further studies should incorporate standardised microbial tolerance assessments for light-based therapies to better assess the reproducibility of these observations.
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Affiliation(s)
- Sanjay Marasini
- Department of Ophthalmology, New Zealand National Eye Centre, The University of Auckland, New Zealand.
| | - Leon G Leanse
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Vaccine and Immunotherapy Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Tianhong Dai
- Wellman Center for Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Vaccine and Immunotherapy Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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4
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All living cells are cognitive. Biochem Biophys Res Commun 2020; 564:134-149. [PMID: 32972747 DOI: 10.1016/j.bbrc.2020.08.120] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/28/2020] [Accepted: 08/19/2020] [Indexed: 12/24/2022]
Abstract
All living cells sense and respond to changes in external or internal conditions. Without that cognitive capacity, they could not obtain nutrition essential for growth, survive inevitable ecological changes, or correct accidents in the complex processes of reproduction. Wherever examined, even the smallest living cells (prokaryotes) display sophisticated regulatory networks establishing appropriate adaptations to stress conditions that maximize the probability of survival. Supposedly "simple" prokaryotic organisms also display remarkable capabilities for intercellular signalling and multicellular coordination. These observations indicate that all living cells are cognitive.
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Jones DL, Baxter BK. DNA Repair and Photoprotection: Mechanisms of Overcoming Environmental Ultraviolet Radiation Exposure in Halophilic Archaea. Front Microbiol 2017; 8:1882. [PMID: 29033920 PMCID: PMC5626843 DOI: 10.3389/fmicb.2017.01882] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 09/14/2017] [Indexed: 12/31/2022] Open
Abstract
Halophilic archaea push the limits of life at several extremes. In particular, they are noted for their biochemical strategies in dealing with osmotic stress, low water activity and cycles of desiccation in their hypersaline environments. Another feature common to their habitats is intense ultraviolet (UV) radiation, which is a challenge that microorganisms must overcome. The consequences of high UV exposure include DNA lesions arising directly from bond rearrangement of adjacent bipyrimidines, or indirectly from oxidative damage, which may ultimately result in mutation and cell death. As such, these microorganisms have evolved a number of strategies to navigate the threat of DNA damage, which we differentiate into two categories: DNA repair and photoprotection. Photoprotection encompasses damage avoidance strategies that serve as a "first line of defense," and in halophilic archaea include pigmentation by carotenoids, mechanisms of oxidative damage avoidance, polyploidy, and genomic signatures that make DNA less susceptible to photodamage. Photolesions that do arise are addressed by a number of DNA repair mechanisms that halophilic archaea efficiently utilize, which include photoreactivation, nucleotide excision repair, base excision repair, and homologous recombination. This review seeks to place DNA damage, repair, and photoprotection in the context of halophilic archaea and the solar radiation of their hypersaline environments. We also provide new insight into the breadth of strategies and how they may work together to produce remarkable UV-resistance for these microorganisms.
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Affiliation(s)
| | - Bonnie K. Baxter
- Department of Biology, Great Salt Lake Institute, Westminster College, Salt Lake City, UT, United States
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Paul VG, Mormile MR. A case for the protection of saline and hypersaline environments: a microbiological perspective. FEMS Microbiol Ecol 2017; 93:3950317. [DOI: 10.1093/femsec/fix091] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 07/09/2017] [Indexed: 11/12/2022] Open
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Hu Q, Zhang XX, Jia S, Huang K, Tang J, Shi P, Ye L, Ren H. Metagenomic insights into ultraviolet disinfection effects on antibiotic resistome in biologically treated wastewater. WATER RESEARCH 2016; 101:309-317. [PMID: 27267479 DOI: 10.1016/j.watres.2016.05.092] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 05/14/2016] [Accepted: 05/29/2016] [Indexed: 05/08/2023]
Abstract
High-throughput sequencing-based metagenomic approaches were used to comprehensively investigate ultraviolet effects on the microbial community structure, and diversity and abundance of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in biologically treated wastewater. After ultraviolet radiation, some dominant genera, like Aeromonas and Halomonas, in the wastewater almost disappeared, while the relative abundance of some minor genera including Pseudomonas and Bacillus increased dozens of times. Metagenomic analysis showed that 159 ARGs within 14 types were detectable in the samples, and the radiation at 500 mJ/cm(2) obviously increased their total relative abundance from 31.68 ppm to 190.78 ppm, which was supported by quantitative real time PCR. As the dominant persistent ARGs, multidrug resistance genes carried by Pseudomonas and bacitracin resistance gene bacA carried by Bacillus mainly contributed to the ARGs abundance increase. Bacterial community shift and MGEs replication induced by the radiation might drive the resistome alteration. The findings may shed new light on the mechanism behind the ultraviolet radiation effects on antibiotic resistance in wastewater.
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Affiliation(s)
- Qing Hu
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Xu-Xiang Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, Nanjing 210023, China.
| | - Shuyu Jia
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Kailong Huang
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Junying Tang
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Peng Shi
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Lin Ye
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, Nanjing 210023, China.
| | - Hongqiang Ren
- State Key Laboratory of Pollution Control and Resource Reuse, Environmental Health Research Center, School of the Environment, Nanjing University, Nanjing 210023, China
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8
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Gilmore SF, Yao AI, Tietel Z, Kind T, Facciotti MT, Parikh AN. Role of squalene in the organization of monolayers derived from lipid extracts of Halobacterium salinarum. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:7922-30. [PMID: 23713788 PMCID: PMC4438081 DOI: 10.1021/la401412t] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We have studied interfacial compressibility and lateral organization in monolayer configurations of total (squalene containing) and polar (squalene-devoid) lipid extracts of Halobacterium salinarum NRC-1, an extremely halophilic archaeon. Pressure-area isotherms derived from Langmuir experiments reveal that packing characteristics and elastic compressibility are strongly influenced by the presence of squalene in the total lipid extract. In conjunction with control experiments using mixtures of DPhPC and squalene, our results establish that the presence of squalene significantly extends elastic area compressibility of total lipid extracts, suggesting it has a role in facilitating tighter packing of archaeal lipid mixtures. Moreover, we find that squalene also influences spatial organization in archaeal membranes. Epifluorescence and atomic force microscopy characterization of Langmuir monolayers transferred onto solid hydrophilic substrates reveal an unusual domain morphology. Individual domains of microscopic dimensions (as well as their extended networks) exhibiting a peculiar bowl-like topography are evident in atomic force microscopy images. The tall rims outlining individual domains indicate that squalene accumulates at the domain periphery in a manner similar to the accumulation of cholesterol at domain boundaries in their mixtures with phospholipids. Taken together, the results presented here support the notion that squalene plays a role in modulating molecular packing and lateral organization (i.e., domain formation) in the membranes of archaea analogous to that of cholesterol in eukaryotic membranes.
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Affiliation(s)
- Sean F. Gilmore
- Department of Applied Science, University of California, Davis
| | - Andrew I. Yao
- Department of Biomedical Engineering, University of California,
Davis
- Genome Center, University of California, Davis
| | | | - Tobias Kind
- Genome Center, University of California, Davis
| | - Marc T. Facciotti
- Department of Biomedical Engineering, University of California,
Davis
- Genome Center, University of California, Davis
| | - Atul N. Parikh
- Department of Biomedical Engineering, University of California,
Davis
- Department of Chemical Engineering and Materials Science, University
of California, Davis
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9
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Trigui H, Masmoudi S, Brochier-Armanet C, Maalej S, Dukan S. Survival of extremely and moderately halophilic isolates of Tunisian solar salterns after UV-B or oxidative stress. Can J Microbiol 2011; 57:923-33. [PMID: 22017705 DOI: 10.1139/w11-087] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adaptation to a solar saltern environment requires mechanisms providing tolerance not only to salinity but also to UV radiation (UVR) and to reactive oxygen species (ROS). We cultivated prokaryote halophiles from two different salinity ponds: the concentrator M1 pond (240 g·L(-1) NaCl) and the crystallizer TS pond (380 g·L(-1) NaCl). We then estimated UV-B and hydrogen peroxide resistance according to the optimal salt concentration for growth of the isolates. We observed a higher biodiversity of bacterial isolates in M1 than in TS. All strains isolated from TS appeared to be extremely halophilic Archaea from the genus Halorubrum. Culturable strains isolated from M1 included extremely halophilic Archaea (genera Haloferax, Halobacterium, Haloterrigena, and Halorubrum) and moderately halophilic Bacteria (genera Halovibrio and Salicola). We also found that archaeal strains were more resistant than bacterial strains to exposure to ROS and UV-B. All organisms tested were more resistant to UV-B exposure at the optimum NaCl concentration for their growth, which is not always the case for H(2)O(2). Finally, if these results are extended to other prokaryotes present in a solar saltern, we could speculate that UVR has greater impact than ROS on the control of prokaryote biodiversity in a solar saltern.
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Affiliation(s)
- Hana Trigui
- Aix-Marseille Université, Laboratoire de chimie bactérienne, Institut de microbiologie de la Méditerranée, Centre national de la recherche scientifique, France
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Ordoñez OF, Flores MR, Dib JR, Paz A, Farías ME. Extremophile culture collection from Andean lakes: extreme pristine environments that host a wide diversity of microorganisms with tolerance to UV radiation. MICROBIAL ECOLOGY 2009; 58:461-473. [PMID: 19495855 DOI: 10.1007/s00248-009-9527-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 04/25/2009] [Indexed: 05/27/2023]
Abstract
A total of 88 bacterial strains were isolated from six Andean lakes situated at altitudes ranging from 3,400 to 4,600 m above sea level: L. Aparejos (4,200 m), L. Negra (4,400 m), L. Verde (4,460 m), L. Azul (4,400 m), L. Vilama (4,600 m), and Salina Grande (3,400 m). Salinity ranged from 0.4 to 117 ppm. General diversity was determined by denaturing gradient gel electrophoresis (DGGE) analysis. From the excised DGGE bands, 182 bacterial sequences of good quality were obtained. Gammaproteobacteria and Cytophaga/Flavobacterium/Bacteroides (CFB) were the most abundant phylogenetic groups with 42% and 18% of identified bands, respectively. The isolated strains were identified by sequence analysis. Isolated bacteria were subjected to five different UV-B exposure times: 0.5, 3, 6, 12, and 24 h. Afterwards, growth of each isolate was monitored and resistance was classified according to the growth pattern. A wide interspecific variation among the 88 isolates was observed. Medium and highly resistant strains accounted for 43.2% and 28.4% of the isolates, respectively, and only 28.4% was sensitive. Resistance to solar radiation was equally distributed among the isolates from the different lakes regardless of the salinity of the lakes and pigmentation of isolates. Of the highly resistant isolates, 44.5% belonged to gammaproteobacteria, 33.3% to betaproteobacteria, 40% to alphaproteobacteria, 50% to CFB, and among gram-positive organisms, 33.3% were HGC and 44.5% were Firmicutes. Most resistant strains belonged to genera like Exiguobaceterium sp., Acinetobacter sp., Bacillus sp., Micrococcus sp., Pseudomonas sp., Sphyngomonas sp., Staphylococcus sp., and Stenotrophomonas sp. The current study provides further evidence that gammaproteobacteria are the most abundant and the most UV-B-resistant phylogenetic group in Andean lakes and that UV resistance in bacteria isolated from these environments do not depend on pigmentation and tolerance to salinity.
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Affiliation(s)
- Omar F Ordoñez
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Belgrano y Pasaje Caseros, 4000 Tucumán, Argentina
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11
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Occurrence of resistance to antibiotics, UV-B, and arsenic in bacteria isolated from extreme environments in high-altitude (above 4400 m) Andean wetlands. Curr Microbiol 2008; 56:510-7. [PMID: 18330637 DOI: 10.1007/s00284-008-9103-2] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Accepted: 01/01/2007] [Indexed: 10/22/2022]
Abstract
High-altitude Andean wetlands are pristine environments with extreme conditions such as high UV radiation, high heavy metal content (mainly arsenic), high salinity, and oligotrophy. In this paper, the UV-B resistance and tolerance to arsenic of phylogenetically characterized bacteria (Actinobacteria [six isolates], Firmicutes [four isolates], and gamma-Proteobacteria [three isolates]) isolated from Laguna Vilama (4400-m altitude) and Laguna Azul (4560 m) were determined. In addition, given that multiple antibiotic resistances were also determined, a relationship between antibiotic resistances as a consequence of mutagenic ability or in relation to metal resistance is proposed. High UV-B resistances were found, since after 30 min (0.7 KJ m(-2)) and 60 min (1.4 KJ m(-2)) of irradiation, most of the studied bacteria did not show a decreased survival; what is more, many of them had an improved survival with the increased doses. Augmentations in mutagenesis rates were observed after UV-B irradiation in only 4 of the 13 tested isolates. Arsenite tolerance was also established in 8 of the 13 tested strains: Staphylococcus saprophyticus A3 and Micrococcus sp. A7, which were able to grow in media containing up to 10 mM As(III). Finally, predominance of antibiotic resistances (azithromycin, erythromycin, clarithromycin, roxithromycin, streptomycin, chloramphenicol, gentamycin, kanamycin, tetracycline, and ampicillin) was found, in all the isolated strains from both wetlands, with unexpectedly high minimal inhibitory concentrations (MICs; >2 mg mL(-1)) for macrolides. These results demonstrate that in extreme environments like high-altitude wetlands there is a correlation of multiresistances to UV-B radiation and arsenic, and that antibiotic resistances are also widespread in these pristine environments, where antibiotic selective pressure is supposed to be absent.
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12
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Zhou P, Wen J, Oren A, Chen M, Wu M. Genomic survey of sequence features for ultraviolet tolerance in haloarchaea (family Halobacteriaceae). Genomics 2007; 90:103-9. [PMID: 17498923 DOI: 10.1016/j.ygeno.2007.03.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 03/10/2007] [Accepted: 03/27/2007] [Indexed: 11/22/2022]
Abstract
We have investigated the strategy of Halobacterium sp. NRC-1 and other members of the family Halobacteriaceae to survive ultraviolet (UV) irradiation, based on an integrated analysis of various genomic and proteomic features such as dinucleotide composition and distribution of tetranucleotides in the genome and amino acid composition of the proteins. The low dipyrimidine content may help Halobacterium reduce formation of photoproducts in its genome. The usage of residues susceptible to reactive oxygen species attack is reduced significantly in Halobacterium, which helps the organism to minimize protein damage. We then correlated the expression of the zim gene with the genomic structure to reexamine the importance of the putative mismatch repair pathway proposed previously. Our results showed that Halobacterium sp. NRC-1 and other haloarchaea (Haloarcula marismortui, Haloquadratum walsbyi) have optimized their genomic and proteomic structures to reduce damage induced by UV irradiation, often present at high levels in habitats where these organisms thrive.
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Affiliation(s)
- Peng Zhou
- Department of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
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Williams PD, Eichstadt SL, Kokjohn TA, Martin EL. Effects of Ultraviolet Radiation on the Gram-Positive Marine Bacterium Microbacterium maritypicum. Curr Microbiol 2007; 55:1-7. [PMID: 17551790 DOI: 10.1007/s00284-006-0349-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Accepted: 10/30/2006] [Indexed: 10/23/2022]
Abstract
Although extensive information is available on the effect ultraviolet (UV) radiation has on Gram-negative marine bacteria, there is a scarcity of data concerning UV radiation and Gram-positive marine bacteria. The focus of this paper is on Microbacterium maritypicum, with the Gram-negative Vibrio natriegens being used as a standard of comparison. M. maritypicum exhibited growth over a NaCl range of 0-1000 mM: , with optimum growth occurring between 0 and 400 mM: NaCl. In contrast, V. natriegens grew over a NaCl span of 250-1000 mM: , with best growth being observed between 250 and 600 mM: NaCl. UV radiation experiments were done using the medium with 250 mM: NaCl. For solar (UV-A and B) radiation and log-phase cells, M. maritypicum was determined to be three times more resistant than V. natriegens. For germicidal (UV-C) radiation, the pattern of resistance of the log-phase cells to the lethal effects of the radiation was even more pronounced, with the Gram-positive bacterium being more than 12 to 13 times more resistant. Similar data to the solar and germicidal log-phase UV kill curves were obtained for stationary-phase cells of both organisms. Photoreactivation was observed for both types of cells exposed to UV-C but none for cells treated with UV-A and B. When log phase cells of M.maritypicum were grown at 0.0 and 0.6 M: NaCl and exposed to UV-C radiation, no difference in survivorship patterns was noted from that of 0.25 M: NaCl grown cells. Although this study has only focused on two marine bacteria, our results indicate that the Gram-positive M. maritypicum could have a built-in advantage for survival in some marine ecosystems.
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Affiliation(s)
- Patrick D Williams
- School of Biological Sciences, E-157 Beadle Center, University of Nebraska-Lincoln, Lincoln, NE 68588-0666, USA
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Seaman PF, Day MJ. Isolation and characterization of a bacteriophage with an unusually large genome from the Great Salt Plains National Wildlife Refuge, Oklahoma, USA. FEMS Microbiol Ecol 2007; 60:1-13. [PMID: 17250749 DOI: 10.1111/j.1574-6941.2006.00277.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
In this study we present a bacteriophage isolated from the Great Salt Plains National Wildlife Refuge (GSP) that is shown to have a genome size of 340 kb, unusually large for a bacterial virus. Transmission electron microscopy analysis of the virion showed this to be a Myoviridae, the first reported to infect the genus Halomonas. This temperate phage, PhigspC, exhibits a broad host range, displaying the ability to infect two different Halomonas spp. also isolated from the GSP. The phage infection process demonstrates a high level of tolerance towards temperature, pH and salinity; however, free virions are rapidly inactivated in water unless supplemented with salt. We show that susceptibility to osmotic shock is correlated with the density of the packaged DNA (rho(pack)). Lysogens of Halomonas salina GSP21 were detrimental to host fitness at 10% salinity, but the lysogen was able to grow faster than the wild type at 20% salinity. From these results we propose that the extensive genome of PhigspC may encode environmentally relevant genes (ERGs); genes that are perhaps not essential for the phage life cycle but increase host and phage fitness in some environmental conditions.
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Affiliation(s)
- Paul F Seaman
- Cardiff School of Biosciences, Cardiff University, Park Place, Cardiff, UK
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Fernández Zenoff V, Siñeriz F, Farías ME. Diverse responses to UV-B radiation and repair mechanisms of bacteria isolated from high-altitude aquatic environments. Appl Environ Microbiol 2006; 72:7857-63. [PMID: 17056692 PMCID: PMC1694205 DOI: 10.1128/aem.01333-06] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acinetobacter johnsonii A2 isolated from the natural community of Laguna Azul (Andean Mountains at 4,560 m above sea level), Serratia marcescens MF42, Pseudomonas sp. strain MF8 isolated from the planktonic community, and Cytophaga sp. strain MF7 isolated from the benthic community from Laguna Pozuelos (Andean Puna at 3,600 m above sea level) were subjected to UV-B (3,931 J m-2) irradiation. In addition, a marine Pseudomonas putida strain, 2IDINH, and a second Acinetobacter johnsonii strain, ATCC 17909, were used as external controls. Resistance to UV-B and kinetic rates of light-dependent (UV-A [315 to 400 nm] and cool white light [400 to 700 nm]) and -independent reactivation following exposure were determined by measuring the survival (expressed as CFU) and accumulation of cyclobutane pyrimidine dimers (CPD). Significant differences in survival after UV-B irradiation were observed: Acinetobacter johnsonii A2, 48%; Acinetobacter johnsonii ATCC 17909, 20%; Pseudomonas sp. strain MF8, 40%; marine Pseudomonas putida strain 2IDINH, 12%; Cytophaga sp. strain MF7, 20%; and Serratia marcescens, 21%. Most bacteria exhibited little DNA damage (between 40 and 80 CPD/Mb), except for the benthic isolate Cytophaga sp. strain MF7 (400 CPD/Mb) and Acinetobacter johnsonii ATCC 17909 (160 CPD/Mb). The recovery strategies through dark and light repair were different in all strains. The most efficient in recovering were both Acinetobacter johnsonii A2 and Cytophaga sp. strain MF7; Serratia marcescens MF42 showed intermediate recovery, and in both Pseudomonas strains, recovery was essentially zero. The UV-B responses and recovery abilities of the different bacteria were consistent with the irradiation levels in their native environment.
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Affiliation(s)
- V. Fernández Zenoff
- Planta Piloto de Procesos Industriales Microbiológicos, Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Belgrano y Pje. Caseros, 4000 Tucumán, Argentina
| | - F. Siñeriz
- Planta Piloto de Procesos Industriales Microbiológicos, Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Belgrano y Pje. Caseros, 4000 Tucumán, Argentina
| | - M. E. Farías
- Planta Piloto de Procesos Industriales Microbiológicos, Consejo Nacional de Investigaciones Científicas y Técnicas, Av. Belgrano y Pje. Caseros, 4000 Tucumán, Argentina
- Corresponding author. Mailing address: PROIMI-CONICET, Av. Belgrano y Pje. Caseros, 4000 Tucumán, Argentina. Phone: 54-381-4344888. Fax: 54-381-4344887. E-mail:
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Zenoff VF, Heredia J, Ferrero M, Siñeriz F, Farías ME. Diverse UV-B resistance of culturable bacterial community from high-altitude wetland water. Curr Microbiol 2006; 52:359-62. [PMID: 16604419 DOI: 10.1007/s00284-005-0241-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Accepted: 01/05/2006] [Indexed: 10/24/2022]
Abstract
Isolation of most ultraviolet B (UV-B)-resistant culturable bacteria that occur in the habitat of Laguna Azul, a high-altitude wetland [4554 m above sea level (asl)] from the Northwestern Argentinean Andes, was carried out by culture-based methods. Water from this environment was exposed to UV-B radiation under laboratory conditions during 36 h, at an irradiance of 4.94 W/m2. It was found that the total number of bacteria in water samples decreased; however, most of the community survived long-term irradiation (312 nm) (53.3 kJ/m2). The percentage of bacteria belonging to dominant species did not vary significantly, depending on the number of UV irradiation doses. The most resistant microbes in the culturable community were Gram-positive pigmented species (Bacillus megaterium [endospores and/or vegetative cells], Staphylococcus saprophyticus, and Nocardia sp.). Only one Gram-negative bacterium could be cultivated (Acinetobacter johnsonii). Nocardia sp. that survived doses of 3201 kJ/m2 were the most resistant bacteria to UV-B treatment. This study is the first report on UV-B resistance of a microbial community isolated from high-altitude extreme environments, and proposes a method for direct isolation of UV-B-resistant bacteria from extreme irradiated environments.
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McCready S, Müller JA, Boubriak I, Berquist BR, Ng WL, DasSarma S. UV irradiation induces homologous recombination genes in the model archaeon, Halobacterium sp. NRC-1. SALINE SYSTEMS 2005; 1:3. [PMID: 16176594 PMCID: PMC1224876 DOI: 10.1186/1746-1448-1-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Accepted: 07/04/2005] [Indexed: 02/02/2023]
Abstract
BACKGROUND A variety of strategies for survival of UV irradiation are used by cells, ranging from repair of UV-damaged DNA, cell cycle arrest, tolerance of unrepaired UV photoproducts, and shielding from UV light. Some of these responses involve UV-inducible genes, including the SOS response in bacteria and an array of genes in eukaryotes. To address the mechanisms used in the third branch of life, we have studied the model archaeon, Halobacterium sp. strain NRC-1, which tolerates high levels of solar radiation in its natural hypersaline environment. RESULTS Cells were irradiated with 30-70 J/m(2) UV-C and an immunoassay showed that the resulting DNA damage was largely repaired within 3 hours in the dark. Under such conditions, transcriptional profiling showed the most strongly up-regulated gene was radA1, the archaeal homolog of rad51/recA, which was induced 7-fold. Additional genes involved in homologous recombination, such as arj1 (recJ-like exonuclease), dbp (eukaryote-like DNA binding protein of the superfamily I DNA and RNA helicases), and rfa3 (replication protein A complex), as well as nrdJ, encoding for cobalamin-dependent ribonucleotide reductase involved in DNA metabolism, was also significantly induced in one or more of our experimental conditions. Neither prokaryotic nor eukaryotic excision repair gene homologs were induced and there was no evidence of an SOS-like response. CONCLUSION These results show that homologous recombination plays an important role in the cellular response of Halobacterium sp. NRC-1 to UV damage. Homologous recombination may permit rescue of stalled replication forks, and/or facilitate recombinational repair. In either case, this provides a mechanism for the observed high-frequency recombination among natural populations of halophilic archaea.
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Affiliation(s)
- Shirley McCready
- School of Biological Molecular Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Jochen A Müller
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 701 E. Pratt St., Suite 236, Baltimore, MD 21202 USA
| | - Ivan Boubriak
- School of Biological Molecular Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Brian R Berquist
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 701 E. Pratt St., Suite 236, Baltimore, MD 21202 USA
| | - Wooi Loon Ng
- School of Biological Molecular Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
| | - Shiladitya DasSarma
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, 701 E. Pratt St., Suite 236, Baltimore, MD 21202 USA
- Molecular and Structural Biology Program, Greenebaum Cancer Center, University of Maryland, Baltimore, MD 21201, USA
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Kottemann M, Kish A, Iloanusi C, Bjork S, DiRuggiero J. Physiological responses of the halophilic archaeon Halobacterium sp. strain NRC1 to desiccation and gamma irradiation. Extremophiles 2005; 9:219-27. [PMID: 15844015 DOI: 10.1007/s00792-005-0437-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Accepted: 01/28/2005] [Indexed: 10/25/2022]
Abstract
We report that the halophilic archaeon Halobacterium sp. strain NRC-1 is highly resistant to desiccation, high vacuum and 60Co gamma irradiation. Halobacterium sp. was able to repair extensive double strand DNA breaks (DSBs) in its genomic DNA, produced both by desiccation and by gamma irradiation, within hours of damage induction. We propose that resistance to high vacuum and 60Co gamma irradiation is a consequence of its adaptation to desiccating conditions. Gamma resistance in Halobacterium sp. was dependent on growth stage with cultures in earlier stages exhibiting higher resistance. Membrane pigments, specifically bacterioruberin, offered protection against cellular damages induced by high doses (5 kGy) of gamma irradiation. High-salt conditions were found to create a protective environment against gamma irradiation in vivo by comparing the amount of DSBs induced by ionizing radiation in the chromosomal DNA of Halobacterium sp. to that of the more radiation-sensitive Escherichia coli that grows in lower-salt conditions. No inducible response was observed after exposing Halobacterium sp. to a nonlethal dose (0.5 kGy) of gamma ray and subsequently exposing the cells to either a high dose (5 kGy) of gamma ray or desiccating conditions. We find that the hypersaline environment in which Halobacterium sp. flourishes is a fundamental factor for its resistance to desiccation, damaging radiation and high vacuum.
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Affiliation(s)
- Molly Kottemann
- Department of Cell Biology and Molecular Genetics, University of Maryland, 3221 H.J. Patterson Hall, College Park, MD 20742, USA
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Wilson C, Caton TM, Buchheim JA, Buchheim MA, Schneegurt MA, Miller RV. DNA-repair potential of Halomonas spp. from the Salt Plains Microbial Observatory of Oklahoma. MICROBIAL ECOLOGY 2004; 48:541-549. [PMID: 15696387 DOI: 10.1007/s00248-004-0243-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2003] [Accepted: 04/26/2004] [Indexed: 05/24/2023]
Abstract
The Great Salt Plains (GSP), an unvegetated, barren salt flat that is part of the Salt Plains National Wildlife Refuge near Cherokee, Oklahoma, is the site of the Salt Plains Microbial Observatory. At the GSP the briny remains of an ancient sea rise to the surface, evaporate under dry conditions, and leave crusts of white salt. Adaptation to this environment requires development of coping mechanisms providing tolerance to desiccating conditions due to the high salinity, extreme temperatures, alkaline pH, unrelenting exposure to solar UV radiation, and prevailing winds. Several lines of evidence suggest that the same DNA repair mechanisms that are usually associated with UV light or chemically induced DNA damage are also important in protecting microbes from desiccation. Because little is known about the DNA repair capacity of microorganisms from hypersaline terrestrial environments, we explored the DNA repair capacity of microbial isolates from the GSP. We used survival following exposure to UV light as a convenient tool to assess DNA repair capacity. Two species of Halomonas (H. salina and H. venusta) that have been isolated repeatedly from the GSP were chosen for analysis. The survival profiles were compared to those of Escherichia coli, Pseudomonas aeruginosa, and Halomonas spp. from aquatic saline environments. Survival of GSP organisms exceeded that of the freshwater organism P. aeruginosa, although they survived no better than E. coli. The GSP isolates were much more resistance to killing by UV than were the aquatic species of Halomonas reported in the literature [Martin et al. (2000) Can J Microbiol 46:180-187]. Unlike E. coli, the GSP isolates did not appear to have an inducible, error-prone repair mechanism. However, they demonstrated high levels of spontaneous mutation.
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Affiliation(s)
- C Wilson
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
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Gillespie NB, Wise KJ, Ren L, Stuart JA, Marcy DL, Hillebrecht J, Li Q, Ramos L, Jordan K, Fyvie S, Birge RR. Characterization of the Branched-Photocycle Intermediates P and Q of Bacteriorhodopsin. J Phys Chem B 2002. [DOI: 10.1021/jp021221p] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nathan B. Gillespie
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Kevin J. Wise
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Lei Ren
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Jeffrey A. Stuart
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Duane L. Marcy
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Jason Hillebrecht
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Qun Li
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Lavoisier Ramos
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Kevin Jordan
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Sean Fyvie
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Robert R. Birge
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
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Perlman AM, Wolfe JK, Bush TE, Dyer JK, Martin EL. Adenine toxicity and transport in the moderately halophilic eubacterium Halomonas elongata. J Basic Microbiol 2002; 41:97-104. [PMID: 11441464 DOI: 10.1002/1521-4028(200105)41:2<97::aid-jobm97>3.0.co;2-d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The presence of adenine in the L-alanine defined medium substantially inhibited the growth of the moderately halophilic eubacterium Halomonas elongata. Extensive attempts to reverse the adenine toxicity for growth were made using a variety of purine and pyrimidine compounds, vitamins, and amino acids. Of the compounds tested, only cytosine was found to reverse the adenine growth inhibition. This indicates a mechanism similar to that found for some strains of Escherichia coli in which the presence of exogenous purines (e.g. adenine) was found to stop purine de novo synthesis and repress the synthesis of the pyrimidine salvage enzyme cytosine deaminase. H. elongata was found to possess an active adenine uptake system that was sodium dependent with only lithium having a considerable capacity to replace the sodium. A competition study indicated that the adenine transport system was quite specific. This paper represents the initial study of purine and pyrimidine salvage pathways and adenine uptake for the moderately halophilic eubacteria.
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Affiliation(s)
- A M Perlman
- School of Biological Sciences, University of Nebraska, Lincoln, NE 68588, USA
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