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Pereira-Garcia C, Sanz-Sáez I, Sánchez P, Coutinho FH, Bravo AG, Sánchez O, Acinas SG. Genomic and transcriptomic characterization of methylmercury detoxification in a deep ocean Alteromonas mediterranea ISS312. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 347:123725. [PMID: 38467369 DOI: 10.1016/j.envpol.2024.123725] [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: 10/03/2023] [Revised: 01/12/2024] [Accepted: 03/04/2024] [Indexed: 03/13/2024]
Abstract
Methylmercury (MeHg) is one of the most worrisome pollutants in marine systems. MeHg detoxification is mediated by merB and merA genes, responsible for the demethylation of MeHg and the reduction of inorganic mercury, respectively. Little is known about the biological capacity to detoxify this compound in marine environments, and even less the bacterial transcriptional changes during MeHg detoxification. This study provides the genomic and transcriptomic characterization of the deep ocean bacteria Alteromonas mediterranea ISS312 with capacity for MeHg degradation. Its genome sequence revealed four mer operons containing three merA gene and two merB gene copies, that could be horizontally transferred among distant related genomes by mobile genetic elements. The transcriptomic profiling in the presence of 5 μM MeHg showed that merA and merB genes are within the most expressed genes, although not all mer genes were equally transcribed. Besides, we aimed to identify functional orthologous genes that displayed expression profiles highly similar or identical to those genes within the mer operons, which could indicate they are under the same regulatory controls. We found contrasting expression profiles for each mer operon that were positively correlated with a wide array of functions mostly related to amino acid metabolism, but also to flagellar assembly or two component systems. Also, this study highlights that all merAB genes of the four operons were globally distributed across oceans layers with higher transcriptional activity in the mesopelagic deeper waters. Our study provides new insights about the transcriptional patterns related to the capacity of marine bacteria to detoxify MeHg, with important implications for the understanding of this process in marine ecosystems.
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Affiliation(s)
- Carla Pereira-Garcia
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta 37-49, E08003 Barcelona, Catalunya, Spain; Department of Genetics and Microbiology, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Catalunya, Spain.
| | - Isabel Sanz-Sáez
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta 37-49, E08003 Barcelona, Catalunya, Spain; Department of Environmental Chemistry, IDAEA-CSIC, Barcelona, Catalunya, Spain
| | - Pablo Sánchez
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta 37-49, E08003 Barcelona, Catalunya, Spain
| | - Felipe H Coutinho
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta 37-49, E08003 Barcelona, Catalunya, Spain
| | - Andrea G Bravo
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta 37-49, E08003 Barcelona, Catalunya, Spain
| | - Olga Sánchez
- Department of Genetics and Microbiology, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Catalunya, Spain
| | - Silvia G Acinas
- Department of Marine Biology and Oceanography, Institut de Ciències del Mar, CSIC, Pg. Marítim de la Barceloneta 37-49, E08003 Barcelona, Catalunya, Spain.
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Harsonowati W, Rahayuningsih S, Yuniarti E, Susilowati DN, Manohara D, Sipriyadi, Widyaningsih S, Akhdiya A, Suryadi Y, Tentrem T. Bacterial Metal-Scavengers Newly Isolated from Indonesian Gold Mine-Impacted Area: Bacillus altitudinis MIM12 as Novel Tools for Bio-Transformation of Mercury. MICROBIAL ECOLOGY 2023; 86:1646-1660. [PMID: 36930295 DOI: 10.1007/s00248-023-02203-z] [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: 09/23/2022] [Accepted: 03/02/2023] [Indexed: 06/18/2023]
Abstract
Selikat river, located in the north part of Bengkulu Province, Indonesia, has critical environmental and ecological issues of contamination by mercury due to artisanal small-scale gold mining (ASGM) activities. The present study focused on the identification and bioremediation efficiency of the mercury-resistant bacteria (MRB) isolated from ASGM-impacted areas in Lebong Tambang village, Bengkulu Province, and analyzed their merA gene function in transforming Hg2+ to Hg0. Thirty-four MRB isolates were isolated, and four out of the 34 isolates exhibited not only the highest degree of resistance to Hg (up to 200 ppm) but also to cadmium (Cd), chromium (Cr), copper (Cu), and lead (Pb). Further analysis shows that all four selected isolates harbor a merA operon-encoded mercuric ion (Hg2+) reductase enzyme, with the Hg bioremediation efficiency varying from 71.60 to 91.30%. Additionally, the bioremediation efficiency for Cd, Cr, Cu, and Pb ranged from 54.36 to 98.37%. Among the 34, two isolates identified as Bacillus altitudinis possess effective and superior multi-metal degrading capacity up to 91.30% for Hg, 98.07% for Cu, and 54.36% for Cr. A pilot-scale study exhibited significant in situ bioremediation of Hg from gold mine tailings of 82.10 and 95.16% at 4- and 8-day intervals, respectively. Interestingly, translated nucleotide blast against bacteria and Bacilli merA sequence databases suggested that B. altitudinis harbor merA gene is the first case among Bacilli with the possibility exhibits a novel mechanism of bioremediation, considering our new finding. This study is the first to report the structural and functional Hg-resistant bacterial diversity of unexplored ASGM-impacted areas, emphasizing their biotechnological potential as novel tools for the biological transformation and adsorption of mercury and other toxic metals.
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Affiliation(s)
- Wiwiek Harsonowati
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia.
- Agrobiology and Bioresources Department, School of Agriculture, Utsunomiya University, 350 Mine-Machi, Utsunomiya, 321-8505, Tochigi, Japan.
| | - Sri Rahayuningsih
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Erny Yuniarti
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Dwi Ningsih Susilowati
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Dyah Manohara
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Sipriyadi
- Biology Department, Faculty of Mathematics and Natural Science, Universitas Bengkulu, Jalan W.R Supratman, Kandang Limun, Bengkulu, 38125, Indonesia
| | - Sri Widyaningsih
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Alina Akhdiya
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Yadi Suryadi
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
| | - Titi Tentrem
- Research Center for Horticultural and Estate Crops, Research Organization for Agriculture and Food, National Research and Innovation Agency (BRIN), Cibinong Science Center, Bogor, 16915, Indonesia
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Priyadarshanee M, Chatterjee S, Rath S, Dash HR, Das S. Cellular and genetic mechanism of bacterial mercury resistance and their role in biogeochemistry and bioremediation. JOURNAL OF HAZARDOUS MATERIALS 2022; 423:126985. [PMID: 34464861 DOI: 10.1016/j.jhazmat.2021.126985] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 08/17/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
Mercury (Hg) is a highly toxic element that occurs at low concentrations in nature. However, various anthropogenic and natural sources contribute around 5000 to 8000 metric tons of Hg per year, rapidly deteriorating the environmental conditions. Mercury-resistant bacteria that possess the mer operon system have the potential for Hg bioremediation through volatilization from the contaminated milieus. Thus, bacterial mer operon plays a crucial role in Hg biogeochemistry and bioremediation by converting both reactive inorganic and organic forms of Hg to relatively inert, volatile, and monoatomic forms. Both the broad-spectrum and narrow-spectrum bacteria harbor many genes of mer operon with their unique definitive functions. The presence of mer genes or proteins can regulate the fate of Hg in the biogeochemical cycle in the environment. The efficiency of Hg transformation depends upon the nature and diversity of mer genes present in mercury-resistant bacteria. Additionally, the bacterial cellular mechanism of Hg resistance involves reduced Hg uptake, extracellular sequestration, and bioaccumulation. The presence of unique physiological properties in a specific group of mercury-resistant bacteria enhances their bioremediation capabilities. Many advanced biotechnological tools also can improve the bioremediation efficiency of mercury-resistant bacteria to achieve Hg bioremediation.
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Affiliation(s)
- Monika Priyadarshanee
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India
| | - Shreosi Chatterjee
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India
| | - Sonalin Rath
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India
| | - Hirak R Dash
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India
| | - Surajit Das
- Laboratory of Environmental Microbiology and Ecology (LEnME), Department of Life Science, National Institute of Technology Rourkela, Rourkela 769 008, Odisha, India.
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Joshi G, Meena B, Verma P, Nayak J, Vinithkumar NV, Dharani G. Deep-sea mercury resistant bacteria from the Central Indian Ocean: A potential candidate for mercury bioremediation. MARINE POLLUTION BULLETIN 2021; 169:112549. [PMID: 34182201 DOI: 10.1016/j.marpolbul.2021.112549] [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: 02/04/2021] [Revised: 05/19/2021] [Accepted: 05/24/2021] [Indexed: 06/13/2023]
Abstract
Deep-sea bacteria when grown in normal environmental conditions get morphologically and genetically adapted to resist the provided culture conditions for their survival, making them a possible aspirant in mercury bioremediation. In this study, seawater samples were collected from different depths of the Central Indian Ocean and seven mercury resistant bacteria (resistant to 100 mg L-1 concentration of inorganic Hg as HgCl2) were isolated. Based on 16S rRNA gene sequencing, the identified isolates belong to the genera Pseudomonas, Bacillus and Pseudoalteromonas. The presence of the merA gene in the isolates contributes to the effective volatilization of mercury. The Inductively Coupled Plasma Mass-Spectroscopy analysis revealed that the isolates can reduce up to >80% of inorganic mercury. Moreover, Fourier Transform Infrared spectrum analysis indicates that functional groups play a key role in the mechanism of adaptation towards Hg2+ reduction. Thus, the deep-sea bacteria expressed significant tolerance and reduction potential towards ionic mercury.
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Affiliation(s)
- Gajendra Joshi
- Atal Centre for Ocean Science and Technology for Islands, National Institute of Ocean Technology, Ministry of Earth Sciences, Government of India, Port Blair 744103, Andaman and Nicobar Islands, India.
| | - Balakrishnan Meena
- Atal Centre for Ocean Science and Technology for Islands, National Institute of Ocean Technology, Ministry of Earth Sciences, Government of India, Port Blair 744103, Andaman and Nicobar Islands, India
| | - Pankaj Verma
- Ocean Science and Technology for Islands, National Institute of Ocean Technology, Ministry of Earth Sciences, Government of India, Chennai 600100, India
| | - Jibananand Nayak
- Atal Centre for Ocean Science and Technology for Islands, National Institute of Ocean Technology, Ministry of Earth Sciences, Government of India, Port Blair 744103, Andaman and Nicobar Islands, India
| | - Nambali Valsalan Vinithkumar
- Atal Centre for Ocean Science and Technology for Islands, National Institute of Ocean Technology, Ministry of Earth Sciences, Government of India, Port Blair 744103, Andaman and Nicobar Islands, India
| | - Gopal Dharani
- Ocean Science and Technology for Islands, National Institute of Ocean Technology, Ministry of Earth Sciences, Government of India, Chennai 600100, India
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Dell'Anno F, Brunet C, van Zyl LJ, Trindade M, Golyshin PN, Dell'Anno A, Ianora A, Sansone C. Degradation of Hydrocarbons and Heavy Metal Reduction by Marine Bacteria in Highly Contaminated Sediments. Microorganisms 2020; 8:E1402. [PMID: 32933071 PMCID: PMC7564820 DOI: 10.3390/microorganisms8091402] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/09/2020] [Accepted: 09/10/2020] [Indexed: 01/08/2023] Open
Abstract
Investigations on the ability of bacteria to enhance removal of hydrocarbons and reduce heavy metal toxicity in sediments are necessary to design more effective bioremediation strategies. In this study, five bacterial strains, Halomonas sp. SZN1, Alcanivorax sp. SZN2, Pseudoalteromonas sp. SZN3, Epibacterium sp. SZN4, and Virgibacillus sp. SZN7, were isolated from polluted sediments from an abandoned industrial site in the Gulf of Naples, Mediterranean Sea, and tested for their bioremediation efficiency on sediment samples collected from the same site. These bacteria were added as consortia or as individual cultures into polluted sediments to assess biodegradation efficiency of polycyclic aromatic hydrocarbons and heavy metal immobilisation capacity. Our results indicate that these bacteria were able to remove polycyclic aromatic hydrocarbons, with a removal rate up to ca. 80% for dibenzo-anthracene. In addition, these bacteria reduced arsenic, lead, and cadmium mobility by promoting their partitioning into less mobile and bioavailable fractions. Microbial consortia generally showed higher performance toward pollutants as compared with pure isolates, suggesting potential synergistic interactions able to enhance bioremediation capacity. Overall, our findings suggest that highly polluted sediments select for bacteria efficient at reducing the toxicity of hazardous compounds, paving the way for scaled-up bioremediation trials.
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Affiliation(s)
- Filippo Dell'Anno
- Stazione Zoologica Anton Dohrn, Istituto Nazionale di Biologia, Ecologia e Biotecnologie Marine, Villa Comunale, 80121 Napoli, Italy
| | - Christophe Brunet
- Stazione Zoologica Anton Dohrn, Istituto Nazionale di Biologia, Ecologia e Biotecnologie Marine, Villa Comunale, 80121 Napoli, Italy
| | - Leonardo Joaquim van Zyl
- Department of Biotechnology, Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Bellville 7535, Cape Town, South Africa
| | - Marla Trindade
- Department of Biotechnology, Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Bellville 7535, Cape Town, South Africa
| | - Peter N Golyshin
- Centre for Environmental Biotechnology (CEB), School of Natural Sciences, Bangor University, Gwynedd LL57 2UW, UK
| | - Antonio Dell'Anno
- Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy
| | - Adrianna Ianora
- Stazione Zoologica Anton Dohrn, Istituto Nazionale di Biologia, Ecologia e Biotecnologie Marine, Villa Comunale, 80121 Napoli, Italy
| | - Clementina Sansone
- Stazione Zoologica Anton Dohrn, Istituto Nazionale di Biologia, Ecologia e Biotecnologie Marine, Villa Comunale, 80121 Napoli, Italy
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Sharma RS, Karmakar S, Kumar P, Mishra V. Application of filamentous phages in environment: A tectonic shift in the science and practice of ecorestoration. Ecol Evol 2019; 9:2263-2304. [PMID: 30847110 PMCID: PMC6392359 DOI: 10.1002/ece3.4743] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/25/2018] [Accepted: 10/30/2018] [Indexed: 02/06/2023] Open
Abstract
Theories in soil biology, such as plant-microbe interactions and microbial cooperation and antagonism, have guided the practice of ecological restoration (ecorestoration). Below-ground biodiversity (bacteria, fungi, invertebrates, etc.) influences the development of above-ground biodiversity (vegetation structure). The role of rhizosphere bacteria in plant growth has been largely investigated but the role of phages (bacterial viruses) has received a little attention. Below the ground, phages govern the ecology and evolution of microbial communities by affecting genetic diversity, host fitness, population dynamics, community composition, and nutrient cycling. However, few restoration efforts take into account the interactions between bacteria and phages. Unlike other phages, filamentous phages are highly specific, nonlethal, and influence host fitness in several ways, which make them useful as target bacterial inocula. Also, the ease with which filamentous phages can be genetically manipulated to express a desired peptide to track and control pathogens and contaminants makes them useful in biosensing. Based on ecology and biology of filamentous phages, we developed a hypothesis on the application of phages in environment to derive benefits at different levels of biological organization ranging from individual bacteria to ecosystem for ecorestoration. We examined the potential applications of filamentous phages in improving bacterial inocula to restore vegetation and to monitor changes in habitat during ecorestoration and, based on our results, recommend a reorientation of the existing framework of using microbial inocula for such restoration and monitoring. Because bacterial inocula and biomonitoring tools based on filamentous phages are likely to prove useful in developing cost-effective methods of restoring vegetation, we propose that filamentous phages be incorporated into nature-based restoration efforts and that the tripartite relationship between phages, bacteria, and plants be explored further. Possible impacts of filamentous phages on native microflora are discussed and future areas of research are suggested to preclude any potential risks associated with such an approach.
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Affiliation(s)
- Radhey Shyam Sharma
- Bioresources and Environmental Biotechnology Laboratory, Department of Environmental StudiesUniversity of DelhiDelhiIndia
| | - Swagata Karmakar
- Bioresources and Environmental Biotechnology Laboratory, Department of Environmental StudiesUniversity of DelhiDelhiIndia
| | - Pankaj Kumar
- Bioresources and Environmental Biotechnology Laboratory, Department of Environmental StudiesUniversity of DelhiDelhiIndia
| | - Vandana Mishra
- Bioresources and Environmental Biotechnology Laboratory, Department of Environmental StudiesUniversity of DelhiDelhiIndia
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Wang YZ, Li D, He M. Application of internal standard method in recombinant luminescent bacteria test. J Environ Sci (China) 2015; 35:128-134. [PMID: 26354701 DOI: 10.1016/j.jes.2015.03.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 03/07/2015] [Accepted: 03/16/2015] [Indexed: 06/05/2023]
Abstract
Mercury and its organic compounds have been of severe concern worldwide due to their damage to the ecosystem and human health. The development of effective and affordable technology to monitor and signal the presence of bioavailable mercury is an urgent need. The Mer gene is a mercury-responsive resistant gene, and a mercury-sensing recombinant luminescent bacterium using the Mer gene was constructed in this study. The mer operon from marine Pseudomonas putida strain SP1 was amplified and fused with prompterless luxCDABE in the pUCD615 plasmid within Escherichia coli cells, resulting in pTHE30-E. coli. The recombinant strain showed high sensitivity and specificity. The detection limit of Hg(2+) was 5nmol/L, and distinct luminescence could be detected in 30min. Cd(2+), Cu(2+), Zn(2+), Ca(2+), Pb(2+), Mg(2+), Mn(2+), and Al(3+) did not interfere with the detection over a range of 10(-5)-1mM. Application of recombinant luminescent bacteria testing in environmental samples has been a controversial issue: especially for metal-sensing recombinant strains, false negatives caused by high cytotoxicity are one of the most important issues when applying recombinant luminescent bacteria in biomonitoring of heavy metals. In this study, by establishing an internal standard approach, the false negative problem was overcome; furthermore, the method can also help to estimate the suspected mercury concentration, which ensures high detection sensitivity of bioavailable Hg(2+).
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Affiliation(s)
- Yong-Zhi Wang
- Environmental Simulation and Pollution Control (ESPC) State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing 100084, China. E-mail: .
| | - Dan Li
- Fudan University, Department of Environmental Science & Engineering, Shanghai 200433, China
| | - Miao He
- Environmental Simulation and Pollution Control (ESPC) State Key Joint Laboratory, School of Environment, Tsinghua University, Beijing 100084, China. E-mail: .
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Mathew DC, Ho YN, Gicana RG, Mathew GM, Chien MC, Huang CC. A rhizosphere-associated symbiont, Photobacterium spp. strain MELD1, and its targeted synergistic activity for phytoprotection against mercury. PLoS One 2015; 10:e0121178. [PMID: 25816328 PMCID: PMC4376707 DOI: 10.1371/journal.pone.0121178] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 01/28/2015] [Indexed: 11/24/2022] Open
Abstract
Though heavy metal such as mercury is toxic to plants and microorganisms, the synergistic activity between them may offer benefit for surviving. In this study, a mercury-reducing bacterium, Photobacterium spp. strain MELD1, with an MIC of 33 mg x kg(-1) mercury was isolated from a severely mercury and dioxin contaminated rhizosphere soil of reed (Phragmites australis). While the whole genome sequencing of MELD1 confirmed the presence of a mer operon, the mercury reductase MerA gene showed 99% sequence identity to Vibrio shilloni AK1 and implicates its route resulted from the event of horizontal gene transfer. The efficiency of MELD1 to vaporize mercury (25 mg x kg(-1), 24 h) and its tolerance to toxic metals and xenobiotics such as lead, cadmium, pentachlorophenol, pentachloroethylene, 3-chlorobenzoic acid, 2,3,7,8-tetrachlorodibenzo-p-dioxin and 1,2,3,7,8,9-hexachlorodibenzo-p-dioxin is promising. Combination of a long yard bean (Vigna unguiculata ssp. Sesquipedalis) and strain MELD1 proved beneficial in the phytoprotection of mercury in vivo. The effect of mercury (Hg) on growth, distribution and tolerance was examined in root, shoot, leaves and pod of yard long bean with and without the inoculation of strain MELD1. The model plant inoculated with MELD1 had significant increases in biomass, root length, seed number, and increased mercury uptake limited to roots. Biolog plate assay were used to assess the sole-carbon source utilization pattern of the isolate and Indole-3-acetic acid (IAA) productivity was analyzed to examine if the strain could contribute to plant growth. The results of this study suggest that, as a rhizosphere-associated symbiont, the synergistic activity between the plant and MELD1 can improve the efficiency for phytoprotection, phytostabilization and phytoremediation of mercury.
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Affiliation(s)
- Dony Chacko Mathew
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, R. O. C
| | - Ying-Ning Ho
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, R. O. C
| | - Ronnie Gicaraya Gicana
- Department of Plant Pathology, National Chung Hsing University, Taichung, Taiwan, R. O. C
| | - Gincy Marina Mathew
- School of Biosciences, Mar Athanasios College for Advanced Studies (MACFAST) BIOCAMPUS, Tiruvalla, Kerala, India
| | - Mei-Chieh Chien
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, R. O. C
| | - Chieh-Chen Huang
- Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan, R. O. C
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Barkay T, Kritee K, Boyd E, Geesey G. A thermophilic bacterial origin and subsequent constraints by redox, light and salinity on the evolution of the microbial mercuric reductase. Environ Microbiol 2011; 12:2904-17. [PMID: 20545753 DOI: 10.1111/j.1462-2920.2010.02260.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Mercuric reductase (MerA) is central to the mercury (Hg) resistance (mer) system, catalyzing the reduction of ionic Hg to volatile Hg(0). A total of 213 merA homologues were identified in sequence databases, the majority of which belonged to microbial lineages that occupy oxic environments. merA was absent among phototrophs and in lineages that inhabit anoxic environments. Phylogenetic reconstructions of MerA indicate that (i) merA originated in a thermophilic bacterium following the divergence of the Archaea and Bacteria with a subsequent acquisition in Archaea via horizontal gene transfer (HGT), (ii) HGT of merA was rare across phylum boundaries and (iii) MerA from marine bacteria formed distinct and strongly supported lineages. Collectively, these observations suggest that a combination of redox, light and salinity conditions constrain MerA to microbial lineages that occupy environments where the most oxidized and toxic form of Hg, Hg(II), predominates. Further, the taxon-specific distribution of MerA with and without a 70 amino acid N-terminal extension may reflect intracellular levels of thiols. In conclusion, MerA likely evolved following the widespread oxygenation of the biosphere in a thermal environment and its subsequent evolution has been modulated by the interactions of Hg with the intra- and extracellular environment of the organism.
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Affiliation(s)
- Tamar Barkay
- Department of Biochemistry and Microbiology, Rutgers University, Lipman Hall, New Brunswick, NJ 08901, USA.
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Isolation and diversity analysis of arsenite-resistant bacteria in communities enriched from deep-sea sediments of the Southwest Indian Ocean Ridge. Extremophiles 2008; 13:39-48. [PMID: 18841325 DOI: 10.1007/s00792-008-0195-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2008] [Accepted: 09/16/2008] [Indexed: 10/21/2022]
Abstract
Microorganisms play an important role in the geobiocycling of arsenic element. However, little is known about the bacteria involved in this process in oceanic environments. In this report, arsenite-resistant bacteria were detected in deep-sea sediments on the Southwest Indian Ridge. From arsenite enriched cultures, 54 isolates were obtained, which showed varied tolerance to arsenite of 2-80 mM. Phylogenetic analysis based on 16S rRNA showed that they mainly belonged to Proteobacteria and Actinobacteria. Denaturing gradient gel electrophoresis revealed that Microbacterium esteraromaticum was the dominant member in the arsenite enriched communities, and this was reconfirmed by 16S rRNA gene library analyses. Thus, M. esteraromaticum showed highest resistant to arsenite among the detected bacteria. These results indicate that there are quite diverse bacteria of arsenite resistance inhabiting the deep sea sediment, which may play a role in the geobiocycling of arsenic element in marine environments.
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Vetriani C, Chew YS, Miller SM, Yagi J, Coombs J, Lutz RA, Barkay T. Mercury adaptation among bacteria from a deep-sea hydrothermal vent. Appl Environ Microbiol 2005; 71:220-6. [PMID: 15640191 PMCID: PMC544242 DOI: 10.1128/aem.71.1.220-226.2005] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Since deep-sea hydrothermal vent fluids are enriched with toxic metals, it was hypothesized that (i) the biota in the vicinity of a vent is adapted to life in the presence of toxic metals and (ii) metal toxicity is modulated by the steep physical-chemical gradients that occur when anoxic, hot fluids are mixed with cold oxygenated seawater. We collected bacterial biomass at different distances from a diffuse flow vent at 9 degrees N on the East Pacific Rise and tested these hypotheses by examining the effect of mercuric mercury [Hg(II)] on vent bacteria. Four of six moderate thermophiles, most of which were vent isolates belonging to the genus Alcanivorax, and six of eight mesophiles from the vent plume were resistant to >10 microM Hg(II) and reduced it to elemental mercury [Hg(0)]. However, four psychrophiles that were isolated from a nearby inactive sulfide structure were Hg(II) sensitive. A neighbor-joining tree constructed from the deduced amino acids of a PCR-amplified fragment of merA, the gene encoding the mercuric reductase (MR), showed that sequences obtained from the vent moderate thermophiles formed a unique cluster (bootstrap value, 100) in the MR phylogenetic tree, which expanded the known diversity of this locus. The temperature optimum for Hg(II) reduction by resting cells and MR activity in crude cell extracts of a vent moderate thermophile corresponded to its optimal growth temperature, 45 degrees C. However, the optimal temperature for activity of the MR encoded by transposon Tn501 was found to be 55 to 65 degrees C, suggesting that, in spite of its original isolation from a mesophile, this MR is a thermophilic enzyme that may represent a relic of early evolution in high-temperature environments. Results showing that there is enrichment of Hg(II) resistance among vent bacteria suggest that these bacteria have an ecological role in mercury detoxification in the vent environment and, together with the thermophilicity of MR, point to geothermal environments as a likely niche for the evolution of bacterial mercury resistance.
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Affiliation(s)
- Costantino Vetriani
- Department of Biochemistry and Microbiology, Rutgers University, New Brunswick, NJ 08901, USA
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Barkay T, Wagner-Döbler I. Microbial Transformations of Mercury: Potentials, Challenges, and Achievements in Controlling Mercury Toxicity in the Environment. ADVANCES IN APPLIED MICROBIOLOGY 2005; 57:1-52. [PMID: 16002008 DOI: 10.1016/s0065-2164(05)57001-1] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Tamar Barkay
- Department of Biochemistry and Microbiology, Cook College, Rutgers University, New Brunswick, New Jersey 08901, USA.
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Distribution of transposons Tn5044 and Tn5070 with noncanonical mer operons in environmental bacterial populations. RUSS J GENET+ 2004. [DOI: 10.1007/s11177-005-0016-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Narita M, Chiba K, Nishizawa H, Ishii H, Huang CC, Kawabata Z, Silver S, Endo G. Diversity of mercury resistance determinants among Bacillus strains isolated from sediment of Minamata Bay. FEMS Microbiol Lett 2003; 223:73-82. [PMID: 12799003 DOI: 10.1016/s0378-1097(03)00325-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Thirty mercury-resistant (Hg R) Bacillus strains were isolated from mercury-polluted sediment of Minamata Bay, Japan. Mercury resistance phenotypes were classified into broad-spectrum (resistant to inorganic Hg(2+) and organomercurials) and narrow-spectrum (resistant to inorganic Hg(2+) and sensitive to organomercurials) groups. Polymerase chain reaction (PCR) product sizes and the restriction nuclease site maps of mer operon regions from all broad-spectrum Hg R Bacillus were identical to that of Bacillus megaterium MB1. On the other hand, the PCR products of the targeted merP (extracellular mercury-binding protein gene) and merA (intracellular mercury reductase protein gene) regions from the narrow-spectrum Hg R Bacillus were generally smaller than those of the B. megaterium MB1 mer determinant. Diversity of gene structure configurations was also observed by restriction fragment length polymorphism (RFLP) profiles of the merA PCR products from the narrow-spectrum Hg R Bacillus. The genetic diversity of narrow-spectrum mer operons was greater than that of broad-spectrum ones.
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Affiliation(s)
- Masaru Narita
- Laboratory of Environmental Biotechnology, Faculty of Engineering, Tohoku Gakuin University, Tagajo, 985-8537, Japan
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Abstract
Bacterial resistance to inorganic and organic mercury compounds (HgR) is one of the most widely observed phenotypes in eubacteria. Loci conferring HgR in Gram-positive or Gram-negative bacteria typically have at minimum a mercuric reductase enzyme (MerA) that reduces reactive ionic Hg(II) to volatile, relatively inert, monoatomic Hg(0) vapor and a membrane-bound protein (MerT) for uptake of Hg(II) arranged in an operon under control of MerR, a novel metal-responsive regulator. Many HgR loci encode an additional enzyme, MerB, that degrades organomercurials by protonolysis, and one or more additional proteins apparently involved in transport. Genes conferring HgR occur on chromosomes, plasmids, and transposons and their operon arrangements can be quite diverse, frequently involving duplications of the above noted structural genes, several of which are modular themselves. How this very mobile and plastic suite of proteins protects host cells from this pervasive toxic metal, what roles it has in the biogeochemical cycling of Hg, and how it has been employed in ameliorating environmental contamination are the subjects of this review.
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Affiliation(s)
- Tamar Barkay
- Department of Biochemistry and Microbiology, Cook College, Rutgers University, New Brunswick, NJ, USA.
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