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Yang M, Wen G, Cao S, Li K, Huang T, Ji G, Wang S, Xue R, Cao R. The formation of double metalimnetic oxygen minima in a drinking water reservoir and its influence on bacterial community. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 860:160540. [PMID: 36574553 DOI: 10.1016/j.scitotenv.2022.160540] [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: 10/08/2022] [Revised: 11/23/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Abstract
Metalimnetic oxygen minima has been reported in many lakes and reservoirs, but the double metalimnetic oxygen minima (DMOM) is so far poorly understood. In this work, we first reported DMOM in the Sanhekou Reservoir, and investigated its formation reason and influence on the bacterial community composition (BCC). The results showed that the two anaerobic layers were formed in DMOM, located at 10 m and 45 m approximately. The rapid water storage process and thermal stratification resulted in the double metalimnions. Algal accumulation, decomposition and oxygen consumption in these regions during the sedimentation process eventually leaded to the formation of DMOM. Water temperature and DO gradients made outstanding contributions to the spatiotemporal environmental heterogeneity and significantly affected the BCC. Depending on the distribution of dissolved oxygen (DO), the storage process could be divided into three periods: DMOM, single MOM period and mixed period. Exiguobacterium and Ralstonia were dominated in DMOM due to the soil discharge and plant decomposition. Besides, BCC presented the largest vertical difference in DMOM and existed the interlayer-similar phenomenon (BCC in the two anaerobic layers were more similar). This study explained the formation of DMOM and its influence on BCC, which was helpful to understand the response of BCC to the storage process and unique DO structure in a moderate eutrophication reservoir.
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Affiliation(s)
- Meng Yang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Gang Wen
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China.
| | - Shuangli Cao
- Hanjiang to Weihe River Valley Water Diversion Project Construction Co. Ltd., Shaanxi Province, Xi'an 710055, People's Republic of China
| | - Kai Li
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Tinglin Huang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Gang Ji
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Sihan Wang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Ruikang Xue
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
| | - Ruihua Cao
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China
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2
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Castro-Severyn J, Pardo-Esté C, Araya-Durán I, Gariazzo V, Cabezas C, Valdés J, Remonsellez F, Saavedra CP. Biochemical, genomic and structural characteristics of the Acr3 pump in Exiguobacterium strains isolated from arsenic-rich Salar de Huasco sediments. Front Microbiol 2022; 13:1047283. [PMID: 36406427 PMCID: PMC9671657 DOI: 10.3389/fmicb.2022.1047283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 10/19/2022] [Indexed: 11/06/2022] Open
Abstract
Arsenic is a highly toxic metalloid of major concern for public safety. However, microorganisms have several resistance mechanisms, particularly the expression of arsenic pumps is a critical component for bacterial ability to expel it and decrease intracellular toxicity. In this study, we aimed to characterize the biochemical, structural, and genomic characteristics of the Acr3 pump among a group of Exiguobacterium strains isolated from different sites of the arsenic-rich Salar de Huasco (SH) ecosystem. We also determined whether the differences in As(III) resistance levels presented by the strains could be attributed to changes in the sequence or structure of this protein. In this context, we found that based on acr3 sequences the strains isolated from the SH grouped together phylogenetically, even though clustering based on gene sequence identity did not reflect the strain’s geographical origin. Furthermore, we determined the genetic context of the acr3 sequences and found that there are two versions of the organization of acr3 gene clusters, that do not reflect the strain’s origin nor arsenic resistance level. We also contribute to the knowledge regarding structure of the Acr3 protein and its possible implications on the functionality of the pump, finding that although important and conserved components of this family of proteins are present, there are several changes in the amino acidic sequences that may affect the interactions among amino acids in the 3D model, which in fact are evidenced as changes in the structure and residues contacts. Finally, we demonstrated through heterologous expression that the Exiguobacterium Acr3 pump does indeed improve the organisms As resistance level, as evidenced in the complemented E. coli strains. The understanding of arsenic detoxification processes in prokaryotes has vast biotechnological potential and it can also provide a lot of information to understand the processes of evolutionary adaptation.
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Affiliation(s)
- Juan Castro-Severyn
- Laboratorio de Microbiología Aplicada y Extremófilos, Departamento de Ingeniería Química, Universidad Católica del Norte, Antofagasta, Chile
| | - Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Ingrid Araya-Durán
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Valentina Gariazzo
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Carolina Cabezas
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Jorge Valdés
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Francisco Remonsellez
- Laboratorio de Microbiología Aplicada y Extremófilos, Departamento de Ingeniería Química, Universidad Católica del Norte, Antofagasta, Chile
- Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Antofagasta, Chile
| | - Claudia P. Saavedra
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
- *Correspondence: Claudia P. Saavedra,
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3
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Gusman VP, Medić DD, Trudić AD, Banović PZ, Nikolić NM. First Isolation of Exiguobacterium aurantiacum in Serbia. Pol J Microbiol 2021; 70:405-407. [PMID: 34584535 PMCID: PMC8458997 DOI: 10.33073/pjm-2021-037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/16/2021] [Accepted: 07/28/2021] [Indexed: 11/21/2022] Open
Abstract
Exiguobacterium aurantiacum is isolated from a variety of environmental samples but rarely from patients. The aim of the study was to represent isolation of unusual bacterial strains that could cause infection in patients. Final identification was performed using matrix-assisted description/ionization time-of-flight mass spectrometry (MALDI-TOF). Two isolates strains of E. aurantiacum were isolated, one isolate from distilled water used during surgical treatment and the second one from a patient with bacteremia after radical prostatectomy, both sensitive to all tested antimicrobials. Environmental strains could cause infection, especially in immunocompromised patients; therefore, rare bacteria testing is required, in which identification special assistance is provided by an automated system MALDI-TOF.
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Affiliation(s)
- Vera P Gusman
- Department of Microbiology, Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Institute of Public Health of Vojvodina, Novi Sad, Serbia
| | - Deana D Medić
- Department of Microbiology, Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Institute of Public Health of Vojvodina, Novi Sad, Serbia
| | - Anika Dj Trudić
- Department of Microbiology, Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Institute for Pulmonary Diseases of Vojvodina, Sremska Kamenica, Serbia
| | - Pavle Z Banović
- Department of Microbiology, Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Pasteur Institute of Novi Sad, Novi Sad, Serbia
| | - Nataša M Nikolić
- Department of Microbiology, Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Institute of Public Health of Vojvodina, Novi Sad, Serbia
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4
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Santos AA, Guedes DO, Barros MUG, Oliveira S, Pacheco ABF, Azevedo SMFO, Magalhães VF, Pestana CJ, Edwards C, Lawton LA, Capelo-Neto J. Effect of hydrogen peroxide on natural phytoplankton and bacterioplankton in a drinking water reservoir: Mesocosm-scale study. WATER RESEARCH 2021; 197:117069. [PMID: 33784604 DOI: 10.1016/j.watres.2021.117069] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/15/2021] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
Cyanobacterial blooms are increasingly reported worldwide, presenting a challenge to water treatment plants and concerning risks to human health and aquatic ecosystems. Advanced oxidative processes comprise efficient and safe methods for water treatment. Hydrogen peroxide (H2O2) has been proposed as a sustainable solution to mitigate bloom-forming cyanobacteria since this group presents a higher sensitivity compared to other phytoplankton, with no major risks to the environment at low concentrations. Here, we evaluated the effects of a single H2O2 addition (10 mg L-1) over 120 h in mesocosms introduced in a reservoir located in a semi-arid region presenting a Planktothrix-dominated cyanobacterial bloom. We followed changes in physical and chemical parameters and in the bacterioplankton composition. H2O2 efficiently suppressed cyanobacteria, green algae, and diatoms over 72 h, leading to an increase in transparency and dissolved organic carbon, and a decrease in dissolved oxygen and pH, while nutrient concentrations were not affected. After 120 h, cyanobacterial abundance remained low and green algae became dominant. 16S rRNA sequencing revealed that the original cyanobacterial bloom was composed by Planktothrix, Cyanobium and Microcystis. Only Cyanobium increased in relative abundance at 120 h, suggesting regrowth. A prominent change in the composition of heterotrophic bacteria was observed with Exiguobacterium, Paracoccus and Deinococcus becoming the most abundant genera after the H2O2 treatment. Our results indicate that this approach is efficient in suppressing cyanobacterial blooms and improving water quality in tropical environments. Monitoring changes in abiotic parameters and the relative abundance of specific bacterial taxa could be used to anticipate the regrowth of cyanobacteria after H2O2 degradation and to indicate where in the reservoir H2O2 should be applied so the effects are still felt in the water treatment plant intake.
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Affiliation(s)
- Allan A Santos
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Brazil.
| | - Dayvson O Guedes
- Department of Hydraulic and Environmental Engineering, Federal University of Ceará, Fortaleza, Brazil
| | - Mário U G Barros
- Department of Hydraulic and Environmental Engineering, Federal University of Ceará, Fortaleza, Brazil; Water Resources Management Company, Fortaleza, Brazil
| | - Samylla Oliveira
- Department of Hydraulic and Environmental Engineering, Federal University of Ceará, Fortaleza, Brazil
| | - Ana B F Pacheco
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Brazil
| | - Sandra M F O Azevedo
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Brazil
| | - Valéria F Magalhães
- Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Brazil
| | - Carlos J Pestana
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, UK
| | - Christine Edwards
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, UK
| | - Linda A Lawton
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, UK
| | - José Capelo-Neto
- Department of Hydraulic and Environmental Engineering, Federal University of Ceará, Fortaleza, Brazil
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5
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Nawaz A, Shahbaz M, Asadullah, Imran A, Marghoob MU, Imtiaz M, Mubeen F. Potential of Salt Tolerant PGPR in Growth and Yield Augmentation of Wheat ( Triticum aestivum L.) Under Saline Conditions. Front Microbiol 2020; 11:2019. [PMID: 33117299 PMCID: PMC7562815 DOI: 10.3389/fmicb.2020.02019] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/30/2020] [Indexed: 12/15/2022] Open
Abstract
Soil salinity has emerged as a major obstacle to meet world food demands. Halo-tolerant plant growth promoting rhizobacteria (PGPR) are potential bioinoculants to enhance crop productivity in saline agriculture. Current work was aimed at studying individual or synergetic impact of salt tolerant PGPR on wheat growth and yield under saline conditions. A pot experiment was conducted on two wheat genotypes (Aas-11; salt tolerant and Galaxy-13; salt sensitive) inoculated with Pseudomonas fluorescence, Bacillus pumilus, and Exiguobacterium aurantiacum alone and in consortium. The salt tolerant variety (Aas-11) exhibited maximum root fresh (665.2%) and dry biomass (865%), free proline (138.12%) and total soluble proteins (155.9%) contents, CAT (41.7%) activity and shoot potassium uptake (81.08%) upon inoculation with B. pumilus, while improved shoot dry weight (70.39%), water (23.49%) and osmotic (29.65%) potential, POD (60.51%) activity, enhanced root potassium (286.36%) and shoot calcium (400%) were manifested by E. aurantiacum. Highest shoot length (14.38%), fresh weight (72.73%), potassium (29.7%) and calcium (400%) acquisition as well as glycinebetaine (270.31%) content were found in plants treated with PGPR consortium. On the other hand, in the salt sensitive variety (Galaxy-13), P. fluorescens treated plants showed significantly improved leaf-water relations, glycinebetaine (10.78%) content, shoot potassium (23.07%), root calcium (50%) uptake, and yield parameters, respectively. Plant root length (71.72%) and potassium content (113.39%), root and shoot fresh and dry biomass, turgor potential (231.02%) and free proline (317.2%) content were maximum upon PGPR inoculation in consortium. Overall, Aas-11 (salt tolerant variety) showed significantly better performance than Galaxy-13 (salt sensitive variety). This study recommends B. pumilus and E. aurantiacum for the salt tolerant (Aas-11) and P. fluorescens for the salt sensitive (Galaxy-13) varieties, as potential bioinoculants to augment their growth and yield through modulation of morpho-physiological and biochemical attributes under saline conditions.
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Affiliation(s)
- Aniqa Nawaz
- Stress Physiology Lab, Department of Botany, University of Agriculture, Faisalabad, Pakistan.,Microbial Physiology Lab, Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Constituent College of Pakistan Institute of Engineering and Applied Sciences, Islamabad, Pakistan
| | - Muhammad Shahbaz
- Stress Physiology Lab, Department of Botany, University of Agriculture, Faisalabad, Pakistan
| | - Asadullah
- Phytohormone Lab, Department of Plant Sciences, Quaid-I-Azam University, Islamabad, Pakistan
| | - Asma Imran
- Microbial Physiology Lab, Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Constituent College of Pakistan Institute of Engineering and Applied Sciences, Islamabad, Pakistan
| | - Muhammad U Marghoob
- Microbial Physiology Lab, Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Constituent College of Pakistan Institute of Engineering and Applied Sciences, Islamabad, Pakistan
| | - Muhammad Imtiaz
- Microbial Physiology Lab, Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Constituent College of Pakistan Institute of Engineering and Applied Sciences, Islamabad, Pakistan
| | - Fathia Mubeen
- Microbial Physiology Lab, Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Constituent College of Pakistan Institute of Engineering and Applied Sciences, Islamabad, Pakistan
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6
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Castro-Severyn J, Pardo-Esté C, Mendez KN, Morales N, Marquez SL, Molina F, Remonsellez F, Castro-Nallar E, Saavedra CP. Genomic Variation and Arsenic Tolerance Emerged as Niche Specific Adaptations by Different Exiguobacterium Strains Isolated From the Extreme Salar de Huasco Environment in Chilean - Altiplano. Front Microbiol 2020; 11:1632. [PMID: 32760381 PMCID: PMC7374977 DOI: 10.3389/fmicb.2020.01632] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/23/2020] [Indexed: 12/17/2022] Open
Abstract
Polyextremophilic bacteria can thrive in environments with multiple stressors such as the Salar de Huasco (SH). Microbial communities in SH are exposed to low atmospheric pressure, high UV radiation, wide temperature ranges, salinity gradient and the presence of toxic compounds such as arsenic (As). In this work we focus on arsenic stress as one of the main adverse factors in SH and bacteria that belong to the Exiguobacterium genus due to their plasticity and ubiquity. Therefore, our aim was to shed light on the effect of niche conditions pressure (particularly arsenic), on the adaptation and divergence (at genotypic and phenotypic levels) of Exiguobacterium strains from five different SH sites. Also, to capture greater diversity in this genus, we use as outgroup five As(III) sensitive strains isolated from Easter Island (Chile) and The Great Salt Lake (United States). For this, samples were obtained from five different SH sites under an arsenic gradient (9 to 321 mg/kg: sediment) and isolated and sequenced the genomes of 14 Exiguobacterium strains, which had different arsenic tolerance levels. Then, we used comparative genomic analysis to assess the genomic divergence of these strains and their association with phenotypic differences such as arsenic tolerance levels and the ability to resist poly-stress. Phylogenetic analysis showed that SH strains share a common ancestor. Consequently, populations were separated and structured in different SH microenvironments, giving rise to multiple coexisting lineages. Hence, this genotypic variability is also evidenced by the COG (Clusters of Orthologous Groups) composition and the size of their accessory genomes. Interestingly, these observations correlate with physiological traits such as growth patterns, gene expression, and enzyme activity related to arsenic response and/or tolerance. Therefore, Exiguobacterium strains from SH are adapted to physiologically overcome the contrasting environmental conditions, like the arsenic present in their habitat.
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Affiliation(s)
- Juan Castro-Severyn
- Laboratorio de Microbiología Aplicada y Extremófilos, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile.,Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Katterinne N Mendez
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Naiyulin Morales
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Sebastián L Marquez
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Franck Molina
- Sys2Diag CNRS/Alcediag, CNRS UMR 3145, Montpellier, France
| | - Francisco Remonsellez
- Laboratorio de Microbiología Aplicada y Extremófilos, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile.,Centro de Investigación Tecnológica del Agua en el Desierto-CEITSAZA, Universidad Católica del Norte, Antofagasta, Chile
| | - Eduardo Castro-Nallar
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Claudia P Saavedra
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
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7
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Remonsellez F, Castro-Severyn J, Pardo-Esté C, Aguilar P, Fortt J, Salinas C, Barahona S, León J, Fuentes B, Areche C, Hernández KL, Aguayo D, Saavedra CP. Characterization and Salt Response in Recurrent Halotolerant Exiguobacterium sp. SH31 Isolated From Sediments of Salar de Huasco, Chilean Altiplano. Front Microbiol 2018; 9:2228. [PMID: 30294311 PMCID: PMC6158405 DOI: 10.3389/fmicb.2018.02228] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 08/31/2018] [Indexed: 12/22/2022] Open
Abstract
Poly-extremophiles microorganisms have the capacity to inhabit hostile environments and can survive several adverse conditions that include as variations in temperature, pH, and salinity, high levels UV light and atmospheric pressure, and even the presence of toxic compounds and the formation of reactive oxygen species (ROS). A halotolerant Exiguobacterium strain was isolated from Salar de Huasco (Chilean Altiplano), a well-known shallow lake area with variable salinity levels, little human intervention, and extreme environmental conditions, which makes it ideal for the study of resistant mechanisms and the evolution of adaptations. This bacterial genus has not been extensively studied, although its cosmopolitan location indicates that it has high levels of plasticity and adaptive capacity. However, to date, there are no studies regarding the tolerance and resistance to salinity and osmotic pressure. We set out to characterize the Exiguobacterium sp. SH31 strain and describe its phenotypical and genotypical response to osmotic stress. In this context, as a first step to characterize the response to the SH31 strain to salinity and to establish the bases for a molecular study, we proposed to compare its response under three salt conditions (0, 25, and 50 g/l NaCl). Using different physiology, genomic, and transcriptomic approaches, we determined that the bacterium is able to grow properly in a NaCl concentration of up to 50 g/l; however, the best growth rate was observed at 25 g/l. Although the presence of flagella is not affected by salinity, motility was diminished at 25 g/l NaCl and abolished at 50 g/l. Biofilm formation was induced proportionally with increases in salinity, which was expected. These phenotypic results correlated with the expression of related genes: fliG and fliS Motility); opuBA and putP (transport); glnA, proC, gltA, and gbsA (compatible solutes); ywqC, bdlA, luxS y pgaC (biofilm and stress response); and therefore, we conclude that this strain effectively modifies gene expression and physiology in a differential manner when faced with different concentrations of NaCl and these modifications aid survival.
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Affiliation(s)
- Francisco Remonsellez
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
- Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Antofagasta, Chile
| | - Juan Castro-Severyn
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Pablo Aguilar
- Lake and Glacier Ecology Research Group, Institute of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Jonathan Fortt
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Cesar Salinas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Sergio Barahona
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Joice León
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Bárbara Fuentes
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Carlos Areche
- Departamento de Química, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Klaudia L. Hernández
- Centro de Investigación Marina Quintay, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile
| | - Daniel Aguayo
- Center for Bioinformatics and Integrative Biology, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Claudia P. Saavedra
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
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8
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Hu Z, Chen X, Chang J, Yu J, Tong Q, Li S, Niu H. Compositional and predicted functional analysis of the gut microbiota of Radix auricularia (Linnaeus) via high-throughput Illumina sequencing. PeerJ 2018; 6:e5537. [PMID: 30186698 PMCID: PMC6118204 DOI: 10.7717/peerj.5537] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 08/08/2018] [Indexed: 12/14/2022] Open
Abstract
Due to its wide distribution across the world, the snail Radix auricularia plays a central role in the transferal of energy and biomass by consuming plant biomass in freshwater systems. The gut microbiota are involved in the nutrition, digestion, immunity, and development of snails, particularly for cellulolytic bacteria, which greatly contribute to the digestion of plant fiber. For the first time, this study characterized the gut bacterial communities of R. auricularia, as well as predicted functions, using the Illumina Miseq platform to sequence 16S rRNA amplicons. Both juvenile snails (JS) and adult snails (AS) were sampled. The obtained 251,072 sequences were rarefied to 214,584 sequences and clustered into 1,196 operational taxonomic units (OTUs) with 97% sequence identity. The predominant phyla were Proteobacteria (JS: 36.0%, AS: 31.6%) and Cyanobacteria (JS: 16.3%, AS: 19.5%), followed by Chloroflexi (JS: 9.7%, AS: 13.1%), Firmicutes (JS: 14.4%, AS: 6.7%), Actinobacteria (JS: 8.2%, AS: 12.6%), and Tenericutes (JS: 7.3%, AS: 6.2%). The phylum Cyanobacteria may have originated from the plant diet instead of the gut microbiome. A total of 52 bacterial families and 55 genera were found with >1% abundance in at least one sample. A large number of species could not be successfully identified, which could indicate the detection of novel ribotypes or result from insufficient availability of snail microbiome data. The core microbiome consisted of 469 OTUs, representing 88.4% of all sequences. Furthermore, the predicted function of bacterial community of R. auricularia performed by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States suggests that functions related to metabolism and environmental information processing were enriched. The abundance of carbohydrate suggests a strong capability of the gut microbiome to digest lignin. Our results indicate an abundance of bacteria in both JS and AS, and thus the bacteria in R. auricularia gut form a promising source for novel enzymes, such as cellulolytic enzymes, that may be useful for biofuel production. Furthermore, searching for xenobiotic biodegradation bacteria may be a further important application of these snails.
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Affiliation(s)
- Zongfu Hu
- College of Animal Science and Technology, Inner Mongolia University for Nationalities, Tongliao, People's Republic of China.,College of Animal Science and Technology, Northeast Agricultural University, Harbin, People's Republic of China.,Inner Mongolia Key Laboratory of Toxicant Monitoring and Toxicology, Tongliao, People's Republic of China
| | - Xi Chen
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, People's Republic of China
| | - Jie Chang
- College of Animal Science and Technology, Inner Mongolia University for Nationalities, Tongliao, People's Republic of China
| | - Jianhua Yu
- College of Animal Science and Technology, Inner Mongolia University for Nationalities, Tongliao, People's Republic of China
| | - Qing Tong
- College of Animal Science and Technology, Northeast Agricultural University, Harbin, People's Republic of China
| | - Shuguo Li
- College of Animal Science and Technology, Inner Mongolia University for Nationalities, Tongliao, People's Republic of China
| | - Huaxin Niu
- College of Animal Science and Technology, Inner Mongolia University for Nationalities, Tongliao, People's Republic of China
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