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Ning Q, Chen L, Li F, Zhou G, Zhang C, Ma D, Zhang J. Tradeoffs of microbial life history strategies drive the turnover of microbial-derived organic carbon in coastal saline soils. Front Microbiol 2023; 14:1141436. [PMID: 37032859 PMCID: PMC10076556 DOI: 10.3389/fmicb.2023.1141436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 02/23/2023] [Indexed: 04/11/2023] Open
Abstract
Stable soil organic carbon (SOC) formation in coastal saline soils is important to improve arable land quality and mitigate greenhouse gas emissions. However, how microbial life-history strategies and metabolic traits regulate SOC turnover in coastal saline soils remains unknown. Here, we investigated the effects of microbial life history strategy tradeoffs on microbial carbon use efficiency (CUE) and microbial-derived SOC formation using metagenomic sequencing technology in different salinity soils. The results showed that high-salinity is detrimental to microbial CUE and microbial-derived SOC formation. Moreover, the regulation of nutrients stoichiometry could not mitigate adverse effects of salt stress on microbial CUE, which indicated that microbial-derived SOC formation is independent of stoichiometry in high-salinity soil. Low-salinity soil is dominated by a high growth yield (Y) strategy, such as higher microbial biomass carbon and metabolic traits which are related to amino acid metabolism, carbohydrate metabolism, and cell processes. However, high-salinity soil is dominated by stress tolerance (S) (e.g., higher metabolic functions of homologous recombination, base excision repair, biofilm formation, extracellular polysaccharide biosynthesis, and osmolytes production) and resource acquisition (A) strategies (e.g., higher alkaline phosphatase activity, transporters, and flagellar assembly). These trade-offs of strategies implied that resource reallocation took place. The high-salinity soil microbes diverted investments away from growth yield to microbial survival and resource capture, thereby decreasing biomass turnover efficiency and impeding microbial-derived SOC formation. Moreover, altering the stoichiometry in low-salinity soil caused more investment in the A-strategy, such as the production of more β-glucosidase and β-N-acetyl-glucosaminidase, and increasing bacterial chemotaxis, which thereby reduced microbial-derived SOC formation. Our research reveals that shift the microbial community from S- and A- strategies to the Y-strategy is important to increase the microbial CUE, and thus enhance SOC turnover in coastal saline soils.
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Affiliation(s)
- Qi Ning
- Fengqiu Experimental Station of National Ecosystem Research Network of China, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Lin Chen
- Fengqiu Experimental Station of National Ecosystem Research Network of China, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Fang Li
- College of Resources and Environment, Henan Agricultural University, Zhengzhou, China
| | - Guixiang Zhou
- Fengqiu Experimental Station of National Ecosystem Research Network of China, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Congzhi Zhang
- Fengqiu Experimental Station of National Ecosystem Research Network of China, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Donghao Ma
- Fengqiu Experimental Station of National Ecosystem Research Network of China, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
| | - Jiabao Zhang
- Fengqiu Experimental Station of National Ecosystem Research Network of China, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China
- University of Chinese Academy of Sciences, Beijing, China
- *Correspondence: Jiabao Zhang,
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Perez MF, Kurth D, Farías ME, Soria MN, Castillo Villamizar GA, Poehlein A, Daniel R, Dib JR. First Report on the Plasmidome From a High-Altitude Lake of the Andean Puna. Front Microbiol 2020; 11:1343. [PMID: 32655530 PMCID: PMC7324554 DOI: 10.3389/fmicb.2020.01343] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 05/26/2020] [Indexed: 12/11/2022] Open
Abstract
Mobile genetic elements, including plasmids, drive the evolution of prokaryotic genomes through the horizontal transfer of genes allowing genetic exchange between bacteria. Moreover, plasmids carry accessory genes, which encode functions that may offer an advantage to the host. Thus, it is expected that in a certain ecological niche, plasmids are enriched in accessory functions, which are important for their hosts to proliferate in that niche. Puquio de Campo Naranja is a high-altitude lake from the Andean Puna exposed to multiple extreme conditions, including high UV radiation, alkalinity, high concentrations of arsenic, heavy metals, dissolved salts, high thermal amplitude and low O2 pressure. Microorganisms living in this lake need to develop efficient mechanisms and strategies to cope under these conditions. The aim of this study was to characterize the plasmidome of microbialites from Puquio de Campo Naranja, and identify potential hosts and encoded functions using a deep-sequencing approach. The potential ecological impact of the plasmidome, including plasmids from cultivable and non-cultivable microorganisms, is described for the first time in a lake representing an extreme environment of the Puna. This study showed that the recovered genetic information for the plasmidome was novel in comparison to the metagenome derived from the same environment. The study of the total plasmid population allowed the identification of genetic features typically encoded by plasmids, such as resistance and virulence factors. The resistance genes comprised resistances to heavy metals, antibiotics and stress factors. These results highlight the key role of plasmids for their hosts and impact of extrachromosomal elements to thrive in a certain ecological niche.
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Affiliation(s)
- María Florencia Perez
- Planta Piloto de Procesos Industriales Microbiológicos, Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán, Argentina
| | - Daniel Kurth
- Planta Piloto de Procesos Industriales Microbiológicos, Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán, Argentina
| | - María Eugenia Farías
- Planta Piloto de Procesos Industriales Microbiológicos, Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán, Argentina
| | - Mariana Noelia Soria
- Planta Piloto de Procesos Industriales Microbiológicos, Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán, Argentina
| | - Genis Andrés Castillo Villamizar
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, Göttingen, Germany.,Línea Tecnológica Biocorrosión, Corporación para la Investigación de la Corrosión C.I.C., Piedecuesta, Colombia
| | - Anja Poehlein
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, Göttingen, Germany
| | - Rolf Daniel
- Genomic and Applied Microbiology & Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August University of Göttingen, Göttingen, Germany
| | - Julián Rafael Dib
- Planta Piloto de Procesos Industriales Microbiológicos, Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán, Argentina.,Facultad de Bioquímica, Química y Farmacia, Instituto de Microbiología, Universidad Nacional de Tucumán, San Miguel de Tucumán, Argentina
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Wilks JM, Chen F, Clark BC, Schneegurt MA. Bacterial Growth in Saturated and Eutectic Solutions of Magnesium Sulphate and Potassium Chlorate with Relevance to Mars and the Ocean Worlds. INTERNATIONAL JOURNAL OF ASTROBIOLOGY 2019; 18:502-509. [PMID: 33776587 PMCID: PMC7992186 DOI: 10.1017/s1473550418000502] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Liquid water on Mars might be created by deliquescence of hygroscopic salts or by permafrost melts, both potentially forming saturated brines. Freezing point depression allows these heavy brines to remain liquid in the near-surface environment for extended periods, perhaps as eutectic solutions, at the lowest temperatures and highest salt concentrations where ices and precipitates do not form. Perchlorate and chlorate salts and iron sulfate form brines with low eutectic temperatures and may persist under Mars near-surface conditions, but are chemically harsh at high concentrations and were expected to be incompatible with life, while brines of common sulfate salts on Mars may be more suitable for microbial growth. Microbial growth in saturated brines also may be relevant beyond Mars, to the oceans of Ceres, Enceladus, Europa and Pluto. We have previously shown strong growth of salinotolerant bacteria in media containing 2 M MgSO4 heptahydrate (~50% w/v) at 25 °C. Here we extend those observations to bacterial isolates from Basque Lake, BC and Hot Lake, WA, that grow well in saturated MgSO4 medium (67%) at 25 °C and in 50% MgSO4 medium at 4 °C (56% would be saturated). Psychrotolerant, salinotolerant microbes isolated from Basque Lake soils included Halomonas and Marinococcus, which were identified by 16S rRNA gene sequencing and characterized phenetically. Eutectic liquid medium constituted by 43% MgSO4 at -4 °C supported copious growth of these psychrotolerant Halomonas isolates, among others. Bacterial isolates also grew well at the eutectic for K chlorate (3% at -3 °C). Survival and growth in eutectic solutions increases the possibility that microbes contaminating spacecraft pose a contamination risk to Mars. The cold brines of sulfate and (per)chlorate salts that may form at times on Mars through deliquescence or permafrost melt have now been demonstrated to be suitable microbial habitats, should appropriate nutrients be available and dormant cells become vegetative.
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Affiliation(s)
- Jonathan M. Wilks
- Department of Biological Sciences, Wichita State University, Wichita, KS
| | - Fei Chen
- Planetary Protection Group, Jet Propulsion Laboratory, Pasadena CA
| | | | - Mark A. Schneegurt
- Department of Biological Sciences, Wichita State University, Wichita, KS
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Life in High Salt Concentrations with Changing Environmental Conditions: Insights from Genomic and Phenotypic Analysis of Salinivibrio sp. Microorganisms 2019; 7:microorganisms7110577. [PMID: 31752335 PMCID: PMC6920786 DOI: 10.3390/microorganisms7110577] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/05/2019] [Accepted: 11/15/2019] [Indexed: 12/17/2022] Open
Abstract
Life in salt pans with varying chemical compositions require special adaptation strategies at both the physiological and molecular level. The Marakkanam salt pan in South India is characterized with a high fluctuation in salinity (19–490 ppt), Ultravioletradiation, and heavy metal concentrations. Several bacterial species have been isolated and identified in the view of phylogenetic analysis and for the subsequent production of industrially important enzymes. However, limited information exists on the genomic basis of their survival under variable environmental conditions. To this extent, we sequenced the whole genome of the Salinivibrio sp. HTSP, a moderately halophilic bacterium. We analysed the physiological and genomic attributes of Salinivibrio sp. HTSP to elucidate the strategies of adaptation under various abiotic stresses. The genome size is estimated to be 3.39 Mbp with a mean G + C content of 50.6%, including 3150 coding sequences. The genome possessed osmotic stress-related coding sequences, and genes involved in different pathways of DNA repair mechanisms and genes related to the resistance to toxic metals were identified. The periplasmic stress response genes and genes of different oxidative stress mechanisms were also identified. The tolerance capacity of the bacterial isolates to heavy metals, UV-radiation, and salinity was also confirmed through appropriate laboratory experiments under controlled conditions.
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Al-Jassim N, Mantilla-Calderon D, Wang T, Hong PY. Inactivation and Gene Expression of a Virulent Wastewater Escherichia coli Strain and the Nonvirulent Commensal Escherichia coli DSM1103 Strain upon Solar Irradiation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:3649-3659. [PMID: 28263596 DOI: 10.1021/acs.est.6b05377] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This study examined the decay kinetics and molecular responses of two Escherichia coli strains upon solar irradiation. The first is E. coli PI-7, a virulent and antibiotic-resistant strain that was isolated from wastewater and carries the emerging NDM-1 antibiotic resistance gene. The other strain, E. coli DSM1103, displayed lower virulence and antibiotic resistance than E. coli PI-7. In a buffer solution, E. coli PI-7 displayed a longer lag phase prior to decay and a longer half-life compared with E. coli DSM1103 (6.64 ± 0.63 h and 2.85 ± 0.46 min vs 1.33 ± 0.52 h and 2.04 ± 0.36 min). In wastewater, both E. coli strains decayed slower than they did in buffer. Although solar irradiation remained effective in reducing the numbers of both strains by more than 5-log10 in <24 h, comparative genomics and transcriptomics revealed differences in the genomes and overall regulation of genes between the two E. coli strains. A wider arsenal of genes related to oxidative stress, cellular repair and protective mechanisms were upregulated in E. coli PI-7. Subpopulations of E. coli PI-7 expressed genes related to dormancy and persister cell formation during the late decay phase, which may have accounted for its prolonged persistence. Upon prolonged solar irradiation, both E. coli strains displayed upregulation of genes related to horizontal gene transfer and antibiotic resistance. Virulence functions unique to E. coli PI-7 were also upregulated. Our findings collectively indicated that, whereas solar irradiation is able to reduce total cell numbers, viable E. coli remained and expressed genes that enable survival despite solar treatment. There remains a need for heightened levels of concern regarding risks arising from the dissemination of E. coli that may remain viable in wastewater after solar irradiation.
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Affiliation(s)
- Nada Al-Jassim
- Water Desalination and Reuse Center (WDRC), Biological and Environmental Sciences & Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia
| | - David Mantilla-Calderon
- Water Desalination and Reuse Center (WDRC), Biological and Environmental Sciences & Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia
| | - Tiannyu Wang
- Water Desalination and Reuse Center (WDRC), Biological and Environmental Sciences & Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia
| | - Pei-Ying Hong
- Water Desalination and Reuse Center (WDRC), Biological and Environmental Sciences & Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia
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Gad AH. Cataloguing the bacterial community of the Great Salt Plains, Oklahoma using 16S rRNA based metagenomics pyrosequencing. GENOMICS DATA 2017; 12:54-57. [PMID: 28367406 PMCID: PMC5362135 DOI: 10.1016/j.gdata.2017.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/03/2017] [Accepted: 03/04/2017] [Indexed: 11/01/2022]
Abstract
The Great Salt Plains of Oklahoma (GSP) is an extreme region, a hypersaline environment from marine origin and a unique area of the Salt National Wild Refuge in the north-central region of Oklahoma. In this study we analyzed the diversity and distribution of bacteria in two habitats; vegetated areas (GAB) and salt flat areas (GAS) in the sediments of GSP using the high-throughput techniques of 16S rRNA gene amplicon (V1-V2 regions) metagenomics-454 pyrosequencing. The filtered sequences resulted to a total of 303,723 paired end reads were generated, assigned into 1646 numbers of OTUs and 56.4% G + C content for GAB, and a total of 144,496 paired end reads were generated, assigned into 785 numbers of OTUs and 56.7% G + C content for GAS. All the resulting 16S rRNA was of an average length ~ 187 bp, assigned to 37 bacterial phyla and candidate divisions. The abundant OTUs were affiliated with Proteobacteria (36.2% in GAB and 31.5% in GAS), Alphaproteobacteria (13.3% in GAB and 8.7% in GAS), Gammaproteobacteria (13% in GAB and 14.2% in GAS), Deltaproteobacteria (6.5% in GAB and 6.1% in GAS), Betaproteobacteria (2.6% in GAB and 1.14% in GAS), Bacteroidetes (16.8% in GAB and 24.3% in GAS), Chloroflexi (8.7% in GAB and 6% in GAS), Actinobacteria (8.5% in GAB and 5.8% in GAS) and Firmicutes (6.5% in GAB and 6.6% in GAS). This is the first study of a high resolution microbial phylogenetic profile of the GSP and the findings stipulate evidence of the bacterial heterogeneity that might be originated by surface and subsurface environments and better understanding of the ecosystem dynamics of GSP. Metagenome sequence data are available at NCBI with accession numbers; LT699840-LT700186.
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Affiliation(s)
- Ahmed H Gad
- Department of Biological Science, University of Tulsa, 800 South Tucker Drive, Oliphant Hall 312, Tulsa, OK 74104, United States
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Kurth D, Belfiore C, Gorriti MF, Cortez N, Farias ME, Albarracín VH. Genomic and proteomic evidences unravel the UV-resistome of the poly-extremophile Acinetobacter sp. Ver3. Front Microbiol 2015; 6:328. [PMID: 25954258 PMCID: PMC4406064 DOI: 10.3389/fmicb.2015.00328] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/01/2015] [Indexed: 12/20/2022] Open
Abstract
Ultraviolet radiation can damage biomolecules, with detrimental or even lethal effects for life. Even though lower wavelengths are filtered by the ozone layer, a significant amount of harmful UV-B and UV-A radiation reach Earth's surface, particularly in high altitude environments. high-altitude Andean lakes (HAALs) are a group of disperse shallow lakes and salterns, located at the Dry Central Andes region in South America at altitudes above 3,000 m. As it is considered one of the highest UV-exposed environments, HAAL microbes constitute model systems to study UV-resistance mechanisms in environmental bacteria at various complexity levels. Herein, we present the genome sequence of Acinetobacter sp. Ver3, a gammaproteobacterium isolated from Lake Verde (4,400 m), together with further experimental evidence supporting the phenomenological observations regarding this bacterium ability to cope with increased UV-induced DNA damage. Comparison with the genomes of other Acinetobacter strains highlighted a number of unique genes, such as a novel cryptochrome. Proteomic profiling of UV-exposed cells identified up-regulated proteins such as a specific cytoplasmic catalase, a putative regulator, and proteins associated to amino acid and protein synthesis. Down-regulated proteins were related to several energy-generating pathways such as glycolysis, beta-oxidation of fatty acids, and electronic respiratory chain. To the best of our knowledge, this is the first report on a genome from a polyextremophilic Acinetobacter strain. From the genomic and proteomic data, an "UV-resistome" was defined, encompassing the genes that would support the outstanding UV-resistance of this strain.
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Affiliation(s)
- Daniel Kurth
- Laboratorio de Investigaciones Microbiologicas Lagunas Andinas, Centro Científico Tecnológico, Planta Piloto de Procesos Industriales Microbiológicos - Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán Argentina
| | - Carolina Belfiore
- Laboratorio de Investigaciones Microbiologicas Lagunas Andinas, Centro Científico Tecnológico, Planta Piloto de Procesos Industriales Microbiológicos - Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán Argentina
| | - Marta F Gorriti
- Laboratorio de Investigaciones Microbiologicas Lagunas Andinas, Centro Científico Tecnológico, Planta Piloto de Procesos Industriales Microbiológicos - Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán Argentina
| | - Néstor Cortez
- Centro Científico Tecnológico, IBR - CONICET, Universidad Nacional de Rosario Rosario, Argentina
| | - María E Farias
- Laboratorio de Investigaciones Microbiologicas Lagunas Andinas, Centro Científico Tecnológico, Planta Piloto de Procesos Industriales Microbiológicos - Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán Argentina
| | - Virginia H Albarracín
- Laboratorio de Investigaciones Microbiologicas Lagunas Andinas, Centro Científico Tecnológico, Planta Piloto de Procesos Industriales Microbiológicos - Consejo Nacional de Investigaciones Científicas y Técnicas, San Miguel de Tucumán Argentina ; Facultad de Ciencias Naturales e Instituto Miguel Lillo, Universidad Nacional de Tucumán, San Miguel de Tucumán Argentina
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Schneegurt MA. Colorimetric microbial diversity analysis and halotolerance along a soil salinity gradient at the Great Salt Plains of Oklahoma. Res Microbiol 2012; 164:83-9. [PMID: 23069343 DOI: 10.1016/j.resmic.2012.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 09/18/2012] [Indexed: 11/18/2022]
Abstract
Microbial diversity was measured along a salinity gradient at the Great Salt Plains of Oklahoma using colony color quantified as RGB components of microbial isolate streaks. Numerical taxonomy was performed using a UPGMA method to create trees of relatedness, define OTUs, and calculate diversity indices. Surface soil samples along a 6-m salinity gradient (from hypersaline soil with 7.5% salinity to oligohaline rangeland soil) at WP68 were dilution-plated on SP medium of various salinities and hundreds of random colonies were collected. The salinity tolerance of isolates along the gradient was determined. From the 1364 colonies examined, 338 OTUs were defined by colony color and their distribution statistically analyzed by soil type and the salinity of enrichment media. Most colonies were shades of cream that became distinguishable based on RGB color components. Diversity indices were high overall and it is likely that the OTUs defined by colony color are below the species level, at the strain level, where the greatest diversity lies in this environment. These results are complementary to previous molecular genetic analyses of 16S rRNA clone libraries from soils at the Great Salt Plains. Great diversity at lower taxonomic levels supports the suggestion that gene flow is not highly fragmented, a result of less specialization, as expected given the highly variable salinity observed at the salt flats with rain events.
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Affiliation(s)
- Mark A Schneegurt
- Department of Biological Sciences, Wichita State University, Wichita, KS 67260, USA.
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Crisler J, Newville T, Chen F, Clark B, Schneegurt M. Bacterial growth at the high concentrations of magnesium sulfate found in martian soils. ASTROBIOLOGY 2012; 12:98-106. [PMID: 22248384 PMCID: PMC3277918 DOI: 10.1089/ast.2011.0720] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 10/14/2011] [Indexed: 05/14/2023]
Abstract
The martian surface environment exhibits extremes of salinity, temperature, desiccation, and radiation that would make it difficult for terrestrial microbes to survive. Recent evidence suggests that martian soils contain high concentrations of MgSO₄ minerals. Through warming of the soils, meltwater derived from subterranean ice-rich regolith may exist for an extended period of time and thus allow the propagation of terrestrial microbes and create significant bioburden at the near surface of Mars. The current report demonstrates that halotolerant bacteria from the Great Salt Plains (GSP) of Oklahoma are capable of growing at high concentrations of MgSO₄ in the form of 2 M solutions of epsomite. The epsotolerance of isolates in the GSP bacterial collection was determined, with 35% growing at 2 M MgSO₄. There was a complex physiological response to mixtures of MgSO₄ and NaCl coupled with other environmental stressors. Growth also was measured at 1 M concentrations of other magnesium and sulfate salts. The complex responses may be partially explained by the pattern of chaotropicity observed for high-salt solutions as measured by agar gelation temperature. Select isolates could grow at the high salt concentrations and low temperatures found on Mars. Survival during repetitive freeze-thaw or drying-rewetting cycles was used as other measures of potential success on the martian surface. Our results indicate that terrestrial microbes might survive under the high-salt, low-temperature, anaerobic conditions on Mars and present significant potential for forward contamination. Stringent planetary protection requirements are needed for future life-detection missions to Mars.
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Affiliation(s)
- J.D. Crisler
- Department of Biological Sciences, Wichita State University, Wichita, Kansas
| | - T.M. Newville
- Department of Biological Sciences, Wichita State University, Wichita, Kansas
| | - F. Chen
- Planetary Protection Group, Jet Propulsion Laboratory, NASA, Pasadena, California
| | - B.C. Clark
- Space Science Institute, Boulder, Colorado
| | - M.A. Schneegurt
- Department of Biological Sciences, Wichita State University, Wichita, Kansas
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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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Caton IR, Schneegurt MA. Culture-independent analysis of the soil bacterial assemblage at the Great Salt Plains of Oklahoma. J Basic Microbiol 2011; 52:16-26. [PMID: 21953014 DOI: 10.1002/jobm.201100175] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 07/02/2011] [Indexed: 11/07/2022]
Abstract
The Great Salt Plains (GSP) of Oklahoma is a natural inland terrestrial hypersaline environment that forms evaporite crusts of mainly NaCl. Previous work described GSP bacterial assemblages through the phylogenetic and phenetic characterization of 105 isolates from 46 phylotypes. The current report describes the same bacterial assemblages through culture-independent 16S rRNA gene clone libraries. Although from similar hypersaline mud flats, the bacterial libraries from two sites, WP3 and WP6, were quite different. The WP3 library was dominated by cyanobacteria, mainly Cyanothece and Euhalothece. The WP6 library was rich in anaerobic sulfur-cycle organisms, including abundant Desulfuromonas. This pattern likely reflects differences in abiotic factors, such as frequency of flooding and hydrologic push. While more than 100 OTUs were identified, the assemblages were not as diverse, based on Shannon indexes, as bacterial communities from oligohaline soils. Since natural inland hypersaline soils are relatively unstudied, it was not clear what kind of bacteria would be present. The bacterial assemblage is predominantly genera typically found in hypersaline systems, although some were relatives of microbes common in oligohaline and marine environments. The bacterial clones did not reflect wide functional diversity, beyond phototrophs, sulfur metabolizers, and numerous heterotrophs.
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Affiliation(s)
- Ingrid R Caton
- Department of Biological Sciences, Wichita State University, Wichita, KS, USA
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Jończyk E, Kłak M, Międzybrodzki R, Górski A. The influence of external factors on bacteriophages--review. Folia Microbiol (Praha) 2011; 56:191-200. [PMID: 21625877 PMCID: PMC3131515 DOI: 10.1007/s12223-011-0039-8] [Citation(s) in RCA: 369] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 02/08/2011] [Indexed: 11/23/2022]
Abstract
The ability of bacteriophages to survive under unfavorable conditions is highly diversified. We summarize the influence of different external physical and chemical factors, such as temperature, acidity, and ions, on phage persistence. The relationships between a phage’s morphology and its survival abilities suggested by some authors are also discussed. A better understanding of the complex problem of phage sensitivity to external factors may be useful not only for those interested in pharmaceutical and agricultural applications of bacteriophages, but also for others working with phages.
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Affiliation(s)
- E Jończyk
- Bacteriophage Laboratory, L. Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla 12, 53-114, Wroclaw, Poland
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Demergasso C, Dorador C, Meneses D, Blamey J, Cabrol N, Escudero L, Chong G. Prokaryotic diversity pattern in high-altitude ecosystems of the Chilean Altiplano. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2008jg000836] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Cecilia Demergasso
- Centro de Biotecnología; Universidad Católica del Norte; Antofagasta Chile
- Centro de Investigación Científica y Tecnológica para la Minería; Antofagasta Chile
| | - Cristina Dorador
- Centro de Biotecnología; Universidad Católica del Norte; Antofagasta Chile
| | - Daniela Meneses
- Centro de Biotecnología; Universidad Católica del Norte; Antofagasta Chile
| | | | - Nathalie Cabrol
- Space Science Division; NASA Ames Research Center; Moffett Field California USA
- SETI Carl Sagan Center; Mountain View California USA
| | - Lorena Escudero
- Centro de Biotecnología; Universidad Católica del Norte; Antofagasta Chile
- Centro de Investigación Científica y Tecnológica para la Minería; Antofagasta Chile
| | - Guillermo Chong
- Centro de Investigación Científica y Tecnológica para la Minería; Antofagasta Chile
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Caton TM, Caton IR, Witte LR, Schneegurt MA. Archaeal diversity at the great salt plains of Oklahoma described by cultivation and molecular analyses. MICROBIAL ECOLOGY 2009; 58:519-528. [PMID: 19306116 PMCID: PMC4066810 DOI: 10.1007/s00248-009-9507-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Accepted: 02/22/2009] [Indexed: 05/27/2023]
Abstract
The Great Salt Plains of Oklahoma is a natural inland terrestrial hypersaline environment that forms evaporite crusts of mainly NaCl. Previous work described the bacterial community through the characterization of 105 isolates from 46 phylotypes. The current report describes the archaeal community through both microbial isolation and culture-independent techniques. Nineteen distinct archaea were isolated, and ten were characterized phenetically. Included were isolates phylogenetically related to Haloarcula, Haloferax, Halorubrum, Haloterrigena, and Natrinema. The isolates were aerobic, non-motile, Gram-negative organisms and exhibited little capacity for fermentation. All of the isolates were halophilic, with most requiring at least 15% salinity for growth, and all grew at 30% salinity. The isolates were mainly mesothermic and could grow at alkaline pH (8.5). A 16S rRNA gene library was generated by polymerase chain reaction amplification of direct soil DNA extracts, and 200 clones were sequenced and analyzed. At 99% and 94% sequence identity, 36 and 19 operational taxonomic units (OTUs) were detected, respectively, while 53 and 22 OTUs were estimated by Chao1, respectively. Coverage was relatively high (100% and 59% at 89% and 99% sequence identity, respectively), and the Shannon Index was 3.01 at 99% sequence identity, comparable to or somewhat lower than hypersaline habitats previously studied. Only sequences from Euryarchaeota in the Halobacteriales were detected, and the strength of matches to known sequences was generally low, most near 90% sequence identity. Large clusters were observed that are related to Haloarcula and Halorubrum. More than two-thirds of the sequences were in clusters that did not have close relatives reported in public databases.
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Affiliation(s)
- T M Caton
- Department of Biological Sciences, Wichita State University, Box 26, 1845 Fairmount, Wichita, KS 67260, USA
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Miller RV, Gammon K, Day MJ. Antibiotic resistance among bacteria isolated from seawater and penguin fecal samples collected near Palmer Station, AntarcticaThis article is one of a selection of papers in the Special Issue on Polar and Alpine Microbiology. Can J Microbiol 2009; 55:37-45. [DOI: 10.1139/w08-119] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Antibiotic resistance in aquatic bacteria has increased steadily as a consequence of the widespread use of antibiotics, but practice and international treaty should have limited antibiotic contamination in Antarctica. We estimated antibiotic resistance in microorganisms isolated from the Antarctic marine waters and a penguin rookery, for 2 reasons: (i) as a measure of human impact and (ii) as a potential “snapshot” of the preantibiotic world. Samples were taken at 4 established sampling sites near Palmer Station, which is situated at the southern end of the Palmer Archipelago (64°10′S, 61°50′W). Sites were chosen to provide different potentials for human contamination. Forty 50 mL samples of seawater were collected and colony-forming units (CFU)/mL were determined at 6 and 20 °C. For this study, presumed psychrophiles (growth at 6 °C) were assumed to be native to Antarctic waters, whereas presumed mesophiles (growth at 20 °C but not at 6 °C) were taken to represent introduced organisms. The 20–6 °C CFU/mL ratio was used as a measure of the relative impact to the ecosystem of presumably introduced organisms. This ratio was highest at the site nearest to Palmer Station and decreased with distance from it, suggesting that human presence has impacted the natural microbial flora of the site. The frequency of resistance to 5 common antibiotics was determined in each group of isolates. Overall drug resistance was higher among the presumed mesophiles than the presumed psychrophiles and increased with proximity to Palmer Station, with the presumed mesophiles showing higher frequencies of single and multiple drug resistance than the psychrophile population. The frequency of multidrug resistance followed the same pattern. It appears that multidrug resistance is low among native Antarctic bacteria but is increased by human habitation.
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Affiliation(s)
- Robert V. Miller
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
- School of Biosciences, Cardiff University, Cardiff, CF10 3TL, Wales, UK
| | - Katharine Gammon
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
- School of Biosciences, Cardiff University, Cardiff, CF10 3TL, Wales, UK
| | - Martin J. Day
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
- School of Biosciences, Cardiff University, Cardiff, CF10 3TL, Wales, UK
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Flores MR, Ordoñez OF, Maldonado MJ, Farías ME. Isolation of UV-B resistant bacteria from two high altitude Andean lakes (4,400 m) with saline and non saline conditions. J GEN APPL MICROBIOL 2009; 55:447-58. [PMID: 20118609 DOI: 10.2323/jgam.55.447] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- María R Flores
- CONICET Consejo Nacional de Investigaciones Científicas y Técnicas, LIMLA-PROIMI Planta Piloto de Procesos Industriales Microbiológicos, Tucuman, Argentina.
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Kirkwood AE, Buchheim JA, Buchheim MA, Henley WJ. Cyanobacterial diversity and halotolerance in a variable hypersaline environment. MICROBIAL ECOLOGY 2008; 55:453-65. [PMID: 17653786 DOI: 10.1007/s00248-007-9291-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 04/24/2007] [Accepted: 06/13/2007] [Indexed: 05/16/2023]
Abstract
The Great Salt Plains (GSP) in north-central Oklahoma, USA is an expansive salt flat (approximately 65 km(2)) that is part of the federally protected Salt Plains National Wildlife Refuge. The GSP serves as an ideal environment to study the microbial diversity of a terrestrial, hypersaline system that experiences wide fluctuations in freshwater influx and diel temperature. Our study assessed cyanobacterial diversity at the GSP by focusing on the taxonomic and physiological diversity of GSP isolates, and the 16S rRNA phylogenetic diversity of isolates and environmental clones from three sites (north, central, and south). Taxonomic diversity of isolates was limited to a few genera (mostly Phormidium and Geitlerinema), but physiological diversity based on halotolerance ranges was strikingly more diverse, even between strains of the same phylotype. The phylogenetic tree revealed diversity that spanned a number of cyanobacterial lineages, although diversity at each site was dominated by only a few phylotypes. Unlike other hypersaline systems, a number of environmental clones from the GSP were members of the heterocystous lineage. Although a number of cyanobacterial isolates were close matches with prevalent environmental clones, it is not certain if these clones reflect the same halotolerance ranges of their matching isolates. This caveat is based on the notable disparities we found between strains of the same phylotype and their inherent halotolerance. Our findings support the hypothesis that variable or poikilotrophic environments promote diversification, and in particular, select for variation in ecotype more than phylotype.
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Affiliation(s)
- Andrea E Kirkwood
- Botany Department, Oklahoma State University, Stillwater, OK 74078, USA.
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Luo Q, Groh JL, Ballard JD, Krumholz LR. Identification of genes that confer sediment fitness to Desulfovibrio desulfuricans G20. Appl Environ Microbiol 2007; 73:6305-12. [PMID: 17704273 PMCID: PMC2074997 DOI: 10.1128/aem.00715-07] [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] [Indexed: 11/20/2022] Open
Abstract
Signature-tagged mutants of Desulfovibrio desulfuricans G20 were screened, and 97 genes crucial for sediment fitness were identified. These genes belong to functional categories including signal transduction, binding and transport, insertion elements, and others. Mutants with mutations in genes encoding proteins involved in amino acid biosynthesis, hydrogenase activity, and DNA repair were further characterized.
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Affiliation(s)
- Qingwei Luo
- University of Oklahoma, Department of Botany and Microbiology, 770 Van Vleet Oval, Norman, OK 73019, 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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Litzner BR, Caton TM, Schneegurt MA. Carbon substrate utilization, antibiotic sensitivity, and numerical taxonomy of bacterial isolates from the Great Salt Plains of Oklahoma. Arch Microbiol 2006; 185:286-96. [PMID: 16518618 DOI: 10.1007/s00203-006-0096-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 09/20/2005] [Accepted: 01/25/2006] [Indexed: 11/24/2022]
Abstract
The current work extends the phenotypic characterization of a bacterial culture collection from the Great Salt Plains of Oklahoma. This barren expanse of mud flats is typically crusted with thalassohaline salt evaporites. The initial account of the aerobic heterotrophic bacteria from the Great Salt Plains described 105 halotolerant isolates that represented 47 phylotypes. Extensive phenotypic analyses were performed on 76 isolates representing 37 unique phylotypes. The current report extends these observations for 60 of the isolates by measuring a wider set of phenotypic characteristics. Utilization patterns for 45 carbon substrates were used to assign the isolates into seven coherent phenons, along with several singletons and a group of isolates that did not grow on single carbon substrates. Most of the isolates were able to utilize nearly all of the nitrogen sources tested, with nitrate being the least utilized. Little antibiotic resistance was seen in the collection as a whole; however, certain phenons were enriched for antibiotic-resistant organisms. A total of 81 phenotypic characteristics were used to generate dendrograms. The numerical taxonomy trees essentially agreed with those generated using 16S rRNA gene sequences. The pattern of carbon substrate utilization showed substantial changes at different salinities that may have relevance to the variable salinities microbes experience at the Salt Plains over time.
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Affiliation(s)
- Brandon R Litzner
- Department of Biological Sciences, Wichita State University, Wichita, KS, USA
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