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Chen Y, Guo Y, Liu Y, Xiang Y, Liu G, Zhang Q, Yin Y, Cai Y, Jiang G. Advances in bacterial whole-cell biosensors for the detection of bioavailable mercury: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 868:161709. [PMID: 36682565 DOI: 10.1016/j.scitotenv.2023.161709] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/29/2022] [Accepted: 01/15/2023] [Indexed: 06/17/2023]
Abstract
Mercury (Hg) and its organic compounds, especially monomethylmercury (MeHg), cause major damage to the ecosystem and human health. In surface water or sediments, microorganisms play a crucial role in the methylation and demethylation of Hg. Given that Hg transformation processes are intracellular reactions, accurate assessment of the bioavailability of Hg(II)/MeHg in the environment, particularly for microorganisms, is of major importance. Compared with traditional analytical methods, bacterial whole-cell biosensors (BWCBs) provide a more accurate, convenient, and cost-effective strategy to assess the environmental risks of Hg(II)/MeHg. This Review summarizes recent progress in the application of BWCBs in the detection of bioavailable Hg(II)/MeHg, providing insight on current challenges and strategies. The principle and components of BWCBs for Hg(II)/MeHg bioavailability analysis are introduced. Furthermore, the impact of water chemical factors on the bioavailability of Hg is discussed as are future perspectives of BWCBs in bioavailable Hg analysis and optimization of BWCBs.
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Affiliation(s)
- Yueqian Chen
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
| | - Yingying Guo
- Laboratory of Environmental Nanotechnology and Health, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yanwei Liu
- Laboratory of Environmental Nanotechnology and Health, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yuping Xiang
- Laboratory of Environmental Nanotechnology and Health, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
| | - Guangliang Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States of America
| | - Qinghua Zhang
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yongguang Yin
- School of Environment, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China; Laboratory of Environmental Nanotechnology and Health, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Yong Cai
- Laboratory of Environmental Nanotechnology and Health, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, United States of America
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
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Bioluminescence and Photoreception in Unicellular Organisms: Light-Signalling in a Bio-Communication Perspective. Int J Mol Sci 2021; 22:ijms222111311. [PMID: 34768741 PMCID: PMC8582858 DOI: 10.3390/ijms222111311] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 12/13/2022] Open
Abstract
Bioluminescence, the emission of light catalysed by luciferases, has evolved in many taxa from bacteria to vertebrates and is predominant in the marine environment. It is now well established that in animals possessing a nervous system capable of integrating light stimuli, bioluminescence triggers various behavioural responses and plays a role in intra- or interspecific visual communication. The function of light emission in unicellular organisms is less clear and it is currently thought that it has evolved in an ecological framework, to be perceived by visual animals. For example, while it is thought that bioluminescence allows bacteria to be ingested by zooplankton or fish, providing them with favourable conditions for growth and dispersal, the luminous flashes emitted by dinoflagellates may have evolved as an anti-predation system against copepods. In this short review, we re-examine this paradigm in light of recent findings in microorganism photoreception, signal integration and complex behaviours. Numerous studies show that on the one hand, bacteria and protists, whether autotrophs or heterotrophs, possess a variety of photoreceptors capable of perceiving and integrating light stimuli of different wavelengths. Single-cell light-perception produces responses ranging from phototaxis to more complex behaviours. On the other hand, there is growing evidence that unicellular prokaryotes and eukaryotes can perform complex tasks ranging from habituation and decision-making to associative learning, despite lacking a nervous system. Here, we focus our analysis on two taxa, bacteria and dinoflagellates, whose bioluminescence is well studied. We propose the hypothesis that similar to visual animals, the interplay between light-emission and reception could play multiple roles in intra- and interspecific communication and participate in complex behaviour in the unicellular world.
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Sun D, Zhou X, Liu C, Zhu J, Ru Y, Liu W, Liu J. Fnr Negatively Regulates Prodigiosin Synthesis in Serratia sp. ATCC 39006 During Aerobic Fermentation. Front Microbiol 2021; 12:734854. [PMID: 34603264 PMCID: PMC8485047 DOI: 10.3389/fmicb.2021.734854] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 08/20/2021] [Indexed: 12/18/2022] Open
Abstract
The well-known Crp/Fnr family regulator Fnr has long been recognized as an oxygen sensor to regulate multiple biological processes, including the switch between aerobic/anaerobic metabolism, nitrogen fixation, bioluminescence, infection, and virulence. In most cases, Fnr was found to be active under anaerobic conditions. However, its role in aerobic antibiotic metabolism has not yet been revealed. In this research, we report that in the model organism, Serratia sp. ATCC 39006, Fnr (Ser39006_013370) negatively regulates prodigiosin production by binding to the spacer between the −10 and −35 region in the promoter of prodigiosin biosynthetic gene cluster under aerobic conditions. Fnr was also shown to modulate the anti-bacterial activity and motility by regulating pathway-specific regulatory genes, indicating that Fnr acts as a global regulator in Serratia sp. ATCC 39006. For the first time, we describe that Fnr regulates antibiotic synthesis in the presence of oxygen, which expands the known physiological functions of Fnr and benefits the further investigation of this important transcriptional regulator.
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Affiliation(s)
- Di Sun
- Jiangsu Key Laboratory of Phylogenomics and Comparative Genomics, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Xuge Zhou
- Jiangsu Key Laboratory of Phylogenomics and Comparative Genomics, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Cong Liu
- Jiangsu Key Laboratory of Phylogenomics and Comparative Genomics, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Jingrong Zhu
- Jiangsu Key Laboratory of Phylogenomics and Comparative Genomics, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Yunrui Ru
- Jiangsu Key Laboratory of Phylogenomics and Comparative Genomics, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Weijie Liu
- Jiangsu Key Laboratory of Phylogenomics and Comparative Genomics, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Jiawen Liu
- Jiangsu Key Laboratory of Phylogenomics and Comparative Genomics, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
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A lasting symbiosis: how Vibrio fischeri finds a squid partner and persists within its natural host. Nat Rev Microbiol 2021; 19:654-665. [PMID: 34089008 DOI: 10.1038/s41579-021-00557-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2021] [Indexed: 01/10/2023]
Abstract
As our understanding of the human microbiome progresses, so does the need for natural experimental animal models that promote a mechanistic understanding of beneficial microorganism-host interactions. Years of research into the exclusive symbiosis between the Hawaiian bobtail squid, Euprymna scolopes, and the bioluminescent bacterium Vibrio fischeri have permitted a detailed understanding of those bacterial genes underlying signal exchange and rhythmic activities that result in a persistent, beneficial association, as well as glimpses into the evolution of symbiotic competence. Migrating from the ambient seawater to regions deep inside the light-emitting organ of the squid, V. fischeri experiences, recognizes and adjusts to the changing environmental conditions. Here, we review key advances over the past 15 years that are deepening our understanding of these events.
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Barth C, Weiss MC, Roettger M, Martin WF, Unden G. Origin and phylogenetic relationships of [4Fe-4S]-containing O 2 sensors of bacteria. Environ Microbiol 2018; 20:4567-4586. [PMID: 30225854 DOI: 10.1111/1462-2920.14411] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 09/10/2018] [Indexed: 11/28/2022]
Abstract
The advent of environmental O2 about 2.5 billion years ago forced microbes to metabolically adapt and to develop mechanisms for O2 sensing. Sensing of O2 by [4Fe-4S]2+ to [2Fe-2S]2+ cluster conversion represents an ancient mechanism that is used by FNREc (Escherichia coli), FNRBs (Bacillus subtilis), NreBSa (Staphylococcus aureus) and WhiB3Mt (Mycobacterium tuberculosis). The phylogenetic relationship of these sensors was investigated. FNREc homologues are restricted to the proteobacteria and a few representatives from other phyla. Homologues of FNRBs and NreBSa are located within the bacilli, of WhiB3 within the actinobacteria. Archaea contain no homologues. The data reveal no similarity between the FNREc , FNRBs , NreBSa and WhiB3 sensor families on the sequence and structural levels. These O2 sensor families arose independently in phyla that were already present at the time O2 appeared, their members were subsequently distributed by lateral gene transfer. The chemistry of [4Fe-4S] and [2Fe-2S] cluster formation and interconversion appears to be shared by the sensor protein families. The type of signal output is, however, family specific. The homologues of FNREc and NreBSa vary with regard to the number of Cys residues that coordinate the cluster. It is suggested that the variants derive from lateral gene transfer and gained other functions.
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Affiliation(s)
- C Barth
- Microbiology and Wine Research, Institute for Molecular Physiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - M C Weiss
- Institute for Molecular Evolution, Heinrich Heine University of Düsseldorf, Düsseldorf, Germany
| | - M Roettger
- Institute for Molecular Evolution, Heinrich Heine University of Düsseldorf, Düsseldorf, Germany
| | - W F Martin
- Institute for Molecular Evolution, Heinrich Heine University of Düsseldorf, Düsseldorf, Germany
| | - G Unden
- Microbiology and Wine Research, Institute for Molecular Physiology, Johannes Gutenberg University Mainz, Mainz, Germany
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Volbeda A, Darnault C, Renoux O, Nicolet Y, Fontecilla-Camps JC. The crystal structure of the global anaerobic transcriptional regulator FNR explains its extremely fine-tuned monomer-dimer equilibrium. SCIENCE ADVANCES 2015; 1:e1501086. [PMID: 26665177 PMCID: PMC4672761 DOI: 10.1126/sciadv.1501086] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 10/04/2015] [Indexed: 06/05/2023]
Abstract
The structure of the dimeric holo-fumarate and nitrate reduction regulator (FNR) from Aliivibrio fischeri has been solved at 2.65 Å resolution. FNR globally controls the transition between anaerobic and aerobic respiration in facultative anaerobes through the assembly/degradation of its oxygen-sensitive [4Fe-4S] cluster. In the absence of O2, FNR forms a dimer and specifically binds to DNA, whereas in its presence, the cluster is degraded causing FNR monomerization and DNA dissociation. We have used our crystal structure and the information previously gathered from numerous FNR variants to propose that this process is governed by extremely fine-tuned interactions, mediated by two salt bridges near the amino-terminal cluster-binding domain and an "imperfect" coiled-coil dimer interface. [4Fe-4S] to [2Fe-2S] cluster degradation propagates a conformational signal that indirectly causes monomerization by disrupting the first of these interactions and unleashing the "unzipping" of the FNR dimer in the direction of the carboxyl-terminal DNA binding domain.
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Colton DM, Stabb EV. Rethinking the roles of CRP, cAMP, and sugar-mediated global regulation in the Vibrionaceae. Curr Genet 2015. [PMID: 26215147 DOI: 10.1007/s00294-015-0508-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Many proteobacteria modulate a suite of catabolic genes using the second messenger cyclic 3', 5'-AMP (cAMP) and the cAMP receptor protein (CRP). Together, the cAMP-CRP complex regulates target promoters, usually by activating transcription. In the canonical model, the phosphotransferase system (PTS), and in particular the EIIA(Glc) component for glucose uptake, provides a mechanistic link that modulates cAMP levels depending on glucose availability, resulting in more cAMP and activation of alternative catabolic pathways when glucose is unavailable. Within the Vibrionaceae, cAMP-CRP appears to play the classical role in modulating metabolic pathways; however, it also controls functions involved in natural competence, bioluminescence, pheromone signaling, and colonization of animal hosts. For this group of marine bacteria, chitin is an ecologically relevant resource, and chitin's monomeric sugar N-acetylglucosamine (NAG) supports robust growth while also triggering regulatory responses. Recent studies with Vibrio fischeri indicate that NAG and glucose uptake share EIIA(Glc), yet the responses of cAMP-CRP to these two carbon sources are starkly different. Moreover, control of cAMP levels appears to be more dominantly controlled by export and degradation. Perhaps more surprisingly, although CRP may require cAMP, its activity can be controlled in response to glucose by a mechanism independent of cAMP levels. Future studies in this area promise to shed new light on the role of cAMP and CRP.
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Affiliation(s)
- Deanna M Colton
- Department of Microbiology, University of Georgia, 120 Cedar Street, Athens, GA, 30602, USA
| | - Eric V Stabb
- Department of Microbiology, University of Georgia, 120 Cedar Street, Athens, GA, 30602, USA.
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Abstract
Vibrio fischeri is a bioluminescent, Gram-negative marine bacterium that can be found free living and in a mutualistic association with certain squids and fishes. Over the past decades, the study of V. fischeri has led to important discoveries about bioluminescence, quorum sensing, and the mechanisms that underlie beneficial host-microbe interactions. This chapter highlights what has been learned about metabolic pathways in V. fischeri, and how this information contributes to a broader understanding of the role of bacterial metabolism in host colonization by both beneficial and pathogenic bacteria, as well as in the growth and survival of free-living bacteria.
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The iron-dependent regulator fur controls pheromone signaling systems and luminescence in the squid symbiont Vibrio fischeri ES114. Appl Environ Microbiol 2013; 79:1826-34. [PMID: 23315731 DOI: 10.1128/aem.03079-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Bacteria often use pheromones to coordinate group behaviors in specific environments. While high cell density is required for pheromones to achieve stimulatory levels, environmental cues can also influence pheromone accumulation and signaling. For the squid symbiont Vibrio fischeri ES114, bioluminescence requires pheromone-mediated regulation, and this signaling is induced in the host to a greater extent than in culture, even at an equivalent cell density. Our goal is to better understand this environment-specific control over pheromone signaling and bioluminescence. Previous work with V. fischeri MJ1 showed that iron limitation induces luminescence, and we recently found that ES114 encounters a low-iron environment in its host. Here we show that ES114 induces luminescence at lower cell density and achieves brighter luminescence in low-iron media. This iron-dependent effect on luminescence required ferric uptake regulator (Fur), which we propose influences two pheromone signaling master regulators, LitR and LuxR. Genetic and bioinformatic analyses suggested that under low-iron conditions, Fur-mediated repression of litR is relieved, enabling more LitR to perform its established role as an activator of luxR. Interestingly, Fur may similarly control the LitR homolog SmcR of Vibrio vulnificus. These results reveal an intriguing regulatory link between low-iron conditions, which are often encountered in host tissues, and pheromone-dependent master regulators.
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Contribution of rapid evolution of the luxR-luxI intergenic region to the diverse bioluminescence outputs of Vibrio fischeri strains isolated from different environments. Appl Environ Microbiol 2011; 77:2445-57. [PMID: 21317265 DOI: 10.1128/aem.02643-10] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio fischeri serves as a valuable model of bacterial bioluminescence, its regulation, and its functional significance. Light output varies more than 10,000-fold in wild-type isolates from different environments, yet dim and bright strains have similar organization of the light-producing lux genes, with the activator-encoding luxR divergently transcribed from luxICDABEG. By comparing the genomes of bright strain MJ11 and the dimmer ES114, we found that the lux region has diverged more than most shared orthologs, including those flanking lux. Divergence was particularly high in the intergenic sequence between luxR and luxI. Analysis of the intergenic lux region from 18 V. fischeri strains revealed that, with one exception, sequence divergence essentially mirrored strain phylogeny but with relatively high substitution rates. The bases conserved among intergenic luxR-luxI sequences included binding sites for known regulators, such as LuxR and ArcA, and bases of unknown significance, including a striking palindromic repeat. By using this collection of diverse luxR-luxI regions, we found that expression of P(luxI)-lacZ but not P(luxR)-lacZ transcriptional reporters correlated with the luminescence output of the strains from which the promoters originated. We also found that exchange of a small stretch of the luxI-luxR intergenic region between two strains largely reversed their relative brightness. Our results show that the luxR-luxI intergenic region contributes significantly to the variable luminescence output among V. fischeri strains isolated from different environments, although other elements of strain backgrounds also contribute. Moreover, the lux system appears to have evolved relatively rapidly, suggesting unknown environment-specific selective pressures.
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