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Daniela Rios Ramirez K, Botero Ñañez K, Leonardo Gonzalez Gomez C, Thiago Andrade Moreira Í. Efficient PAHs removal and CO 2 fixation by marine microalgae in wastewater using an airlift photobioreactor for biofuel production. ENVIRONMENTAL RESEARCH 2024; 261:119672. [PMID: 39053760 DOI: 10.1016/j.envres.2024.119672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 06/05/2024] [Accepted: 07/22/2024] [Indexed: 07/27/2024]
Abstract
Microalgae cultures have emerged as a promising strategy in diverse areas, ranging from wastewater treatment to biofuel production, thus contributing to the search for carbon neutrality. These photosynthetic organisms can utilize the resources present in wastewater and fix atmospheric CO2 to produce biomass with high energy potential. In this study, the removal efficiency of Polycyclic Aromatic Hydrocarbons (PAHs), CO2 fixation and lipid content in the biomass produced from microalgae grown in airlift photobioreactor were evaluated. Four mesoscale cultures were carried out: Control (Seawater + Conway medium), Treatment A (Oil Produced Water + Poultry Effluent Water), Treatment B (Poultry Effluent Water + Seawater) and Treatment C (Oil Produced Water, Seawater and nutrients). The impact of biostimulation, through the addition of nutrients, on PAHs removal efficiency (up to 90%), CO2 fixation rate (up to 0.20 g L-1 d-1) and the composition of the generated biomass was observed. Primarily, the addition of nitrates to the culture medium impacted CO2 fixation rate of the microalgae. In addition, a direct correlation was observed between PAHs removal and lipid accumulation in the biomass, up to 36% in dry weight, demonstrating microalgae's ability to take advantage of the organic carbon (PAHs) present in the culture medium to generate lipid-rich biomass. The concentration of polysaccharides in the biomass obtained did not exceed 12% on a dry weight basis, and the Higher Heating Value (HHV) ranged between 17 and 21 MJ kg-1. Finally, the potential of generating hydrogen through pyrolysis was highlighted, taking advantage of the characteristics of biomass as a conversion route to produce biofuels. These results show that microalgae are effective in wastewater treatment and have great potential in producing biofuels, thus contributing to the transition towards more sustainable energy sources and climate change mitigation.
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Affiliation(s)
- Karen Daniela Rios Ramirez
- Institute of Geoscience, Federal University of Bahia (UFBA), Rua Barão de Jeremoabo, s/n, Campus Ondina, 40170-115, Salvador, Bahia, Brazil
| | - Katerine Botero Ñañez
- Institute of Geoscience, Federal University of Bahia (UFBA), Rua Barão de Jeremoabo, s/n, Campus Ondina, 40170-115, Salvador, Bahia, Brazil
| | - Cristian Leonardo Gonzalez Gomez
- Institute of Geoscience, Federal University of Bahia (UFBA), Rua Barão de Jeremoabo, s/n, Campus Ondina, 40170-115, Salvador, Bahia, Brazil
| | - Ícaro Thiago Andrade Moreira
- Institute of Geoscience, Federal University of Bahia (UFBA), Rua Barão de Jeremoabo, s/n, Campus Ondina, 40170-115, Salvador, Bahia, Brazil.
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Ugwuodo CJ, Colosimo F, Adhikari J, Bloodsworth K, Wright SA, Eder J, Mouser PJ. Changes in environmental and engineered conditions alter the plasma membrane lipidome of fractured shale bacteria. Microbiol Spectr 2024; 12:e0233423. [PMID: 38059585 PMCID: PMC10782966 DOI: 10.1128/spectrum.02334-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 10/31/2023] [Indexed: 12/08/2023] Open
Abstract
IMPORTANCE Microorganisms inadvertently introduced into the shale reservoir during fracturing face multiple stressors including brine-level salinities and starvation. However, some anaerobic halotolerant bacteria adapt and persist for long periods of time. They produce hydrogen sulfide, which sours the reservoir and corrodes engineering infrastructure. In addition, they form biofilms on rock matrices, which decrease shale permeability and clog fracture networks. These reduce well productivity and increase extraction costs. Under stress, microbes remodel their plasma membrane to optimize its roles in protection and mediating cellular processes such as signaling, transport, and energy metabolism. Hence, by observing changes in the membrane lipidome of model shale bacteria, Halanaerobium congolense WG10, and mixed consortia enriched from produced fluids under varying subsurface conditions and growth modes, we provide insight that advances our knowledge of the fractured shale biosystem. We also offer data-driven recommendations for improving biocontrol efficacy and the efficiency of energy recovery from unconventional formations.
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Affiliation(s)
- Chika Jude Ugwuodo
- Natural Resources and Earth Systems Science, University of New Hampshire, Durham, New Hampshire, USA
- Department of Civil and Environmental Engineering, University of New Hampshire, Durham, New Hampshire, USA
| | | | | | - Kent Bloodsworth
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Stephanie A. Wright
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Josie Eder
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Paula J. Mouser
- Department of Civil and Environmental Engineering, University of New Hampshire, Durham, New Hampshire, USA
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Onga EA, Vêncio RZN, Koide T. Low Salt Influences Archaellum-Based Motility, Glycerol Metabolism, and Gas Vesicles Biogenesis in Halobacterium salinarum. Microorganisms 2022; 10:2442. [PMID: 36557695 PMCID: PMC9786353 DOI: 10.3390/microorganisms10122442] [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: 11/05/2022] [Revised: 12/05/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022] Open
Abstract
Halobacterium salinarum NRC-1 is an extremophile that grows optimally at 4.3 M NaCl concentration. In spite of being an established model microorganism for the archaea domain, direct comparisons between its proteome and transcriptome during osmotic stress are still not available. Through RNA-seq-based transcriptomics, we compared a low salt (2.6 M NaCl) stress condition with 4.3 M of NaCl and found 283 differentially expressed loci. The more commonly found classes of genes were: ABC-type transporters and transcription factors. Similarities, and most importantly, differences between our findings and previously published datasets in similar experimental conditions are discussed. We validated three important biological processes differentially expressed: gas vesicles production (due to down-regulation of gvpA1b, gvpC1b, gvpN1b, and gvpO1b); archaellum formation (due to down-regulation of arlI, arlB1, arlB2, and arlB3); and glycerol metabolism (due to up-regulation of glpA1, glpB, and glpC). Direct comparison between transcriptomics and proteomics showed 58% agreement between mRNA and protein level changes, pointing to post-transcriptional regulation candidates. From those genes, we highlight rpl15e, encoding for the 50S ribosomal protein L15e, for which we hypothesize an ionic strength-dependent conformational change that guides post-transcriptional processing of its mRNA and, thus, possible salt-dependent regulation of the translation machinery.
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Affiliation(s)
- Evelyn Ayumi Onga
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto 14049-900, Brazil
| | - Ricardo Z. N. Vêncio
- Department of Computation and Mathematics, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-901, Brazil
| | - Tie Koide
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto 14049-900, Brazil
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Anan'ina LN, Gorbunov AA, Pyankova AA. Physiological response of the moderately halophilic psychrotolerant strain Chromohalobacter sp. N1 to salinity change and low temperature. Can J Microbiol 2021; 67:342-348. [PMID: 33666508 DOI: 10.1139/cjm-2020-0299] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The available information on de novo synthesized compatible solutes in response to high medium salinity by bacteria of the Chromohalobacter genus is limited to studies of the mesophilic moderately halophilic strain Chromohalobacter salexigens DSM 3043T. Therefore, there is a need for studies of representatives of other species of the Chromohalobacter genus of the Halomonadaceae family. A moderately halophilic psychrotolerant bacterium, strain N1, closely related to the species Chromohalobacter japonicus was isolated from the salt crust of a rock salt waste pile in Berezniki, Perm Krai, Russia. An intracellular pool of compatible solutes of strain N1 was investigated by NMR spectroscopy. Cells grown in the presence of 5% NaCl at optimal growth temperature (28 °C) accumulated ectoine, glutamate, N(4)-acetyl-l-2,4-diaminobutyrate (NADA), alanine, trehalose, hydroxyectoine, and valine. Such a combination of compatible solutes is unique and distinguishes the strain from C. salexigens DSM 3043T. Hyperosmotic stress induced by 15% NaCl caused the accumulation of ectoine, NADA, and hydroxyectoine but led to a decrease in the amount of alanine, valine, and trehalose. The intracellular pool of glutamate was not significantly changed. A reduction of the growth temperature from 28 to 5 °C led to an increase in the amount of ectoine, NADA, trehalose, and hydroxyectoine. Ectoine was the major compatible solute.
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Affiliation(s)
- Lyudmila N Anan'ina
- Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences - Filial of the Perm Federal Research Centre of the Ural Branch of the Russian Academy of Sciences, 13 Golev Street, Perm 614081, Russia
| | - Aleksey A Gorbunov
- Institute of Technical Chemistry, Filial of the Perm Federal Research Centre of the Ural Branch of the Russian Academy of Sciences, 3 Akademika Koroleva Street, Perm 614013, Russia
| | - Anna A Pyankova
- Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences - Filial of the Perm Federal Research Centre of the Ural Branch of the Russian Academy of Sciences, 13 Golev Street, Perm 614081, Russia
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Kumar S, Paul D, Bhushan B, Wakchaure GC, Meena KK, Shouche Y. Traversing the "Omic" landscape of microbial halotolerance for key molecular processes and new insights. Crit Rev Microbiol 2020; 46:631-653. [PMID: 32991226 DOI: 10.1080/1040841x.2020.1819770] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Post-2005, the biology of the salt afflicted habitats is predominantly studied employing high throughput "Omic" approaches comprising metagenomics, transcriptomics, metatranscriptomics, metabolomics, and proteomics. Such "Omic-based" studies have deciphered the unfamiliar details about microbial salt-stress biology. The MAGs (Metagenome-assembled genomes) of uncultured halophilic microbial lineages such as Nanohaloarchaea and haloalkaliphilic members within CPR (Candidate Phyla Radiation) have been reconstructed from diverse hypersaline habitats. The study of MAGs of such uncultured halophilic microbial lineages has unveiled the genomic basis of salt stress tolerance in "yet to culture" microbial lineages. Furthermore, functional metagenomic approaches have been used to decipher the novel genes from uncultured microbes and their possible role in microbial salt-stress tolerance. The present review focuses on the new insights into microbial salt-stress biology gained through different "Omic" approaches. This review also summarizes the key molecular processes that underlie microbial salt-stress response, and their role in microbial salt-stress tolerance has been confirmed at more than one "Omic" levels.
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Affiliation(s)
- Satish Kumar
- National Centre for Microbial Resource, National Centre for Cell Science, Pune, India.,ICAR-National Institute of Abiotic Stress Management, Baramati, Pune, India
| | - Dhiraj Paul
- National Centre for Microbial Resource, National Centre for Cell Science, Pune, India
| | - Bharat Bhushan
- ICAR-National Bureau of Plant Genetic Resources, New Delhi, India
| | - G C Wakchaure
- ICAR-National Institute of Abiotic Stress Management, Baramati, Pune, India
| | - Kamlesh K Meena
- ICAR-National Institute of Abiotic Stress Management, Baramati, Pune, India
| | - Yogesh Shouche
- National Centre for Microbial Resource, National Centre for Cell Science, Pune, India
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Omara AMA, Sharaf AEMM, El-Hela AA, Shahin AAM, El-Bialy HAA, El-Fouly MZ. Optimizing ectoine biosynthesis using response surface methodology and osmoprotectant applications. Biotechnol Lett 2020; 42:1003-1017. [PMID: 32062816 DOI: 10.1007/s10529-020-02833-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 02/04/2020] [Indexed: 11/28/2022]
Abstract
PURPOSE Numerous applications of compatible salts (osmolytes) as ectoine in food and pharmaceutical industries have been intensively increased nowadays. Decreasing the cost of industrial production of ectoine using low-cost cultivation media and improving the yield through modeling procedures are the main scopes of the present study. METHODS Three statistical design experiments have been successfully applied for screening the parameters affecting the production process, studying the relations among parameters and optimizing the production using response surface methodology. RESULTS A novel semi-synthetic medium based on hydrolyzed corn gluten meal has been developed to cultivate moderate halophilic bacterial strains; Vibrio sp. CS1 and Salinivibrio costicola SH3, and support ectoine synthesis under salinity stress. Two regression equations describe the production process in the new medium have been formulated for each bacterial strain. Response surface optimizer of the central composite model predicts the maximum ectoine production is achieved at incubation time; 63.7 h, pH; 7.47 and salinity; 7.27% for Vibrio sp. CS1 whereas these variables should be adjusted at 56.95 h, 7.089 and 10.34%; on the same order regarding Salinivibrio costicola SH3. In application studies, 50 µg ectoine decreases RBCs hemolysis due to streptolysin O toxin by 21.7% within ten minutes. In addition, 2% ectoine succeeds to increase the viability of lactic acid bacteria in Yogurt as a classic example of functional food during the storage period (7 days). CONCLUSION The present study emphasizes on modeling the process of ectoine production by halophilic bacteria as well as its activity as a cryoprotectant agent.
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Affiliation(s)
- Ahmed M A Omara
- Radiation Microbiology Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority, Cairo, Egypt
| | | | | | - Azza A M Shahin
- Radiation Microbiology Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority, Cairo, Egypt
| | - Heba Abd Alla El-Bialy
- Radiation Microbiology Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority, Cairo, Egypt.
| | - Mohie Z El-Fouly
- Radiation Microbiology Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority, Cairo, Egypt
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The Primary Antisense Transcriptome of Halobacterium salinarum NRC-1. Genes (Basel) 2019; 10:genes10040280. [PMID: 30959844 PMCID: PMC6523106 DOI: 10.3390/genes10040280] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 04/01/2019] [Accepted: 04/01/2019] [Indexed: 12/17/2022] Open
Abstract
Antisense RNAs (asRNAs) are present in diverse organisms and play important roles in gene regulation. In this work, we mapped the primary antisense transcriptome in the halophilic archaeon Halobacterium salinarum NRC-1. By reanalyzing publicly available data, we mapped antisense transcription start sites (aTSSs) and inferred the probable 3′ ends of these transcripts. We analyzed the resulting asRNAs according to the size, location, function of genes on the opposite strand, expression levels and conservation. We show that at least 21% of the genes contain asRNAs in H. salinarum. Most of these asRNAs are expressed at low levels. They are located antisense to genes related to distinctive characteristics of H. salinarum, such as bacteriorhodopsin, gas vesicles, transposases and other important biological processes such as translation. We provide evidence to support asRNAs in type II toxin–antitoxin systems in archaea. We also analyzed public Ribosome profiling (Ribo-seq) data and found that ~10% of the asRNAs are ribosome-associated non-coding RNAs (rancRNAs), with asRNAs from transposases overrepresented. Using a comparative transcriptomics approach, we found that ~19% of the asRNAs annotated in H. salinarum belong to genes with an ortholog in Haloferax volcanii, in which an aTSS could be identified with positional equivalence. This shows that most asRNAs are not conserved between these halophilic archaea.
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Kelly SA, Skvortsov T, Magill D, Quinn DJ, McGrath JW, Allen CCR, Moody TS, Gilmore BF. Characterization of a novel ω-transaminase from a Triassic salt mine metagenome. Biochem Biophys Res Commun 2018; 503:2936-2942. [PMID: 30119883 DOI: 10.1016/j.bbrc.2018.08.073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 08/08/2018] [Indexed: 01/08/2023]
Abstract
Chiral amines are valuable building blocks for the pharmaceutical industry, and are increasingly synthesized by transaminase-mediated (TAm) synthesis. Currently available TAms, primarily isolated from the genomes of cultured mesophilic bacteria, often suffer from a number of drawbacks, including poor substrate range and an inability to tolerate the harsh conditions often demanded by industrial processes. These characteristics have, in part, driven the search for novel biocatalysts from both metagenomic sources and extreme environments. Herein, we report the isolation and characterization of an ω-TAm from a metagenome of a Triassic salt mine in Kilroot, N. Ireland, an extremely hypersaline environment formed circa 220-250 mya. The gene sequence was identified based on homology with existing bacterial TAms, synthesized within a pET28a(+) plasmid and expressed in E. coli BL21 DE3 cells. The resultant 49 kDa protein accepted (S)-methylbenzylamine (MBA) as amino donor and had a specific activity of 0.54 U/mg using α-ketoglutarate (ΑKG) as substrate. Molecular modeling and substrate docking indicated the presence of key residues, conserved in a number of other TAms. Despite the hypersaline environment from which it was isolated, the enzyme displayed low halotolerance, highlighting that not all biocatalysts will demonstrate the extreme characteristics associated with their source environment. This study does however reinforce the viability of mining metagenomic datasets as a means of discovering novel and functional biocatalysts, and adds to a currently scant list of such examples in the field of TAms.
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Affiliation(s)
- Stephen A Kelly
- School of Pharmacy, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Timofey Skvortsov
- School of Pharmacy, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Damian Magill
- School of Biological Sciences, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Derek J Quinn
- Almac, Department of Biocatalysis & Isotope Chemistry, 20 Seagoe Industrial Estate, Craigavon, BT63 5QD, N. Ireland, UK
| | - John W McGrath
- School of Biological Sciences, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Christopher C R Allen
- School of Biological Sciences, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK
| | - Thomas S Moody
- Almac, Department of Biocatalysis & Isotope Chemistry, 20 Seagoe Industrial Estate, Craigavon, BT63 5QD, N. Ireland, UK; Arran Chemical Company Limited, Unit 1 Monksland Industrial Estate, Athlone, Co. Roscommon, Ireland
| | - Brendan F Gilmore
- School of Pharmacy, Queen's University Belfast, Belfast, BT9 7BL, N. Ireland, UK.
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Méheust R, Watson AK, Lapointe FJ, Papke RT, Lopez P, Bapteste E. Hundreds of novel composite genes and chimeric genes with bacterial origins contributed to haloarchaeal evolution. Genome Biol 2018; 19:75. [PMID: 29880023 PMCID: PMC5992828 DOI: 10.1186/s13059-018-1454-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 05/16/2018] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Haloarchaea, a major group of archaea, are able to metabolize sugars and to live in oxygenated salty environments. Their physiology and lifestyle strongly contrast with that of their archaeal ancestors. Amino acid optimizations, which lowered the isoelectric point of haloarchaeal proteins, and abundant lateral gene transfers from bacteria have been invoked to explain this deep evolutionary transition. We use network analyses to show that the evolution of novel genes exclusive to Haloarchaea also contributed to the evolution of this group. RESULTS We report the creation of 320 novel composite genes, both early in the evolution of Haloarchaea during haloarchaeal genesis and later in diverged haloarchaeal groups. One hundred and twenty-six of these novel composite genes derived from genetic material from bacterial genomes. These latter genes, largely involved in metabolic functions but also in oxygenic lifestyle, constitute a different gene pool from the laterally acquired bacterial genes formerly identified. These novel composite genes were likely advantageous for their hosts, since they show significant residence times in haloarchaeal genomes-consistent with a long phylogenetic history involving vertical descent and lateral gene transfer-and encode proteins with optimized isoelectric points. CONCLUSIONS Overall, our work encourages a systematic search for composite genes across all archaeal major groups, in order to better understand the origins of novel prokaryotic genes, and in order to test to what extent archaea might have adjusted their lifestyles by incorporating and recycling laterally acquired bacterial genetic fragments into new archaeal genes.
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Affiliation(s)
- Raphaël Méheust
- Sorbonne Universités, UPMC Univ Paris 06, Institut de Biologie Paris Seine, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7138 Evolution Paris Seine, 75005, Paris, France
| | - Andrew K Watson
- Sorbonne Universités, UPMC Univ Paris 06, Institut de Biologie Paris Seine, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7138 Evolution Paris Seine, 75005, Paris, France
| | | | - R Thane Papke
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, 06269, USA
| | - Philippe Lopez
- Sorbonne Universités, UPMC Univ Paris 06, Institut de Biologie Paris Seine, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7138 Evolution Paris Seine, 75005, Paris, France
| | - Eric Bapteste
- Sorbonne Universités, UPMC Univ Paris 06, Institut de Biologie Paris Seine, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7138 Evolution Paris Seine, 75005, Paris, France.
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Almeida-Dalmet S, Litchfield CD, Gillevet P, Baxter BK. Differential Gene Expression in Response to Salinity and Temperature in a Haloarcula Strain from Great Salt Lake, Utah. Genes (Basel) 2018; 9:genes9010052. [PMID: 29361787 PMCID: PMC5793203 DOI: 10.3390/genes9010052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 01/11/2018] [Accepted: 01/16/2018] [Indexed: 01/01/2023] Open
Abstract
Haloarchaea that inhabit Great Salt Lake (GSL), a thalassohaline terminal lake, must respond to the fluctuating climate conditions of the elevated desert of Utah. We investigated how shifting environmental factors, specifically salinity and temperature, affected gene expression in the GSL haloarchaea, NA6-27, which we isolated from the hypersaline north arm of the lake. Combined data from cultivation, microscopy, lipid analysis, antibiotic sensitivity, and 16S rRNA gene alignment, suggest that NA6-27 is a member of the Haloarcula genus. Our prior study demonstrated that archaea in the Haloarcula genus were stable in the GSL microbial community over seasons and years. In this study, RNA arbitrarily primed PCR (RAP-PCR) was used to determine the transcriptional responses of NA6-27 grown under suboptimal salinity and temperature conditions. We observed alteration of the expression of genes related to general stress responses, such as transcription, translation, replication, signal transduction, and energy metabolism. Of the ten genes that were expressed differentially under stress, eight of these genes responded in both conditions, highlighting this general response. We also noted gene regulation specific to salinity and temperature conditions, such as osmoregulation and transport. Taken together, these data indicate that the GSL Haloarcula strain, NA6-27, demonstrates both general and specific responses to salinity and/or temperature stress, and suggest a mechanistic model for homeostasis that may explain the stable presence of this genus in the community as environmental conditions shift.
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Affiliation(s)
- Swati Almeida-Dalmet
- Department of Environmental Science and Policy, George Mason University, 10900 University Blvd, Manassas, VA 20110, USA.
| | - Carol D Litchfield
- Department of Environmental Science and Policy, George Mason University, 10900 University Blvd, Manassas, VA 20110, USA.
| | - Patrick Gillevet
- Department of Biology, George Mason University, 10900 University Blvd, Manassas, VA 20110, USA.
| | - Bonnie K Baxter
- Great Salt Lake Institute, Westminster College, 1840 South 1300 East, Salt Lake City, UT 84105, USA.
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