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Causes and consequences of pattern diversification in a spatially self-organizing microbial community. THE ISME JOURNAL 2021; 15:2415-2426. [PMID: 33664433 PMCID: PMC8319339 DOI: 10.1038/s41396-021-00942-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 02/06/2021] [Accepted: 02/15/2021] [Indexed: 01/31/2023]
Abstract
Surface-attached microbial communities constitute a vast amount of life on our planet. They contribute to all major biogeochemical cycles, provide essential services to our society and environment, and have important effects on human health and disease. They typically consist of different interacting genotypes that arrange themselves non-randomly across space (referred to hereafter as spatial self-organization). While spatial self-organization is important for the functioning, ecology, and evolution of these communities, the underlying determinants of spatial self-organization remain unclear. Here, we performed a combination of experiments, statistical modeling, and mathematical simulations with a synthetic cross-feeding microbial community consisting of two isogenic strains. We found that two different patterns of spatial self-organization emerged at the same length and time scales, thus demonstrating pattern diversification. This pattern diversification was not caused by initial environmental heterogeneity or by genetic heterogeneity within populations. Instead, it was caused by nongenetic heterogeneity within populations, and we provide evidence that the source of this nongenetic heterogeneity is local differences in the initial spatial positionings of individuals. We further demonstrate that the different patterns exhibit different community-level properties; namely, they have different expansion speeds. Together, our results demonstrate that pattern diversification can emerge in the absence of initial environmental heterogeneity or genetic heterogeneity within populations and can affect community-level properties, thus providing novel insights into the causes and consequences of microbial spatial self-organization.
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Chen F, Ricken J, Xu D, Wegner SV. Bacterial Photolithography: Patterning
Escherichia coli
Biofilms with High Spatial Control Using Photocleavable Adhesion Molecules. ACTA ACUST UNITED AC 2018; 3:e1800269. [DOI: 10.1002/adbi.201800269] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/29/2018] [Indexed: 12/30/2022]
Affiliation(s)
- Fei Chen
- Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany
| | - Julia Ricken
- Department of Biophysical ChemistryUniversity of Heidelberg Im Neuenheimer Feld 253 69120 Heidelberg Germany
| | - Dongdong Xu
- Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany
| | - Seraphine V. Wegner
- Max Planck Institute for Polymer Research Ackermannweg 10 55128 Mainz Germany
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3
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Capo A, Pennacchio A, Varriale A, D'Auria S, Staiano M. The porcine odorant-binding protein as molecular probe for benzene detection. PLoS One 2018; 13:e0202630. [PMID: 30183769 PMCID: PMC6124761 DOI: 10.1371/journal.pone.0202630] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 08/06/2018] [Indexed: 11/19/2022] Open
Abstract
In recent years, air pollution has been a subject of great scientific and public interests for the strong impact on human health. Air pollution is due to the presence in the atmosphere of polluting substances, such as carbon monoxide, sulfur and nitrogen oxides, particulates and volatile organic compounds (VOCs), derived predominantly from various combustion processes. Benzene is a VOC belonging to group-I carcinogens with a toxicity widely demonstrated. The emission limit values and the daily exposure time to benzene (TLV-TWA) are 5μg/m3 (0.00157 ppm) and 1.6mg/m3 (0.5 ppm), respectively. Currently, expensive and time-consuming analytical methods are used for detection of benzene. These methods require to perform a few preliminary steps such as sampling, and matrices pre-treatments. In addition, it is also needed the support of specialized personnel. Recently, single-walled carbon nanotube (SWNTs) gas sensors with a limit detection (LOD) of 20 ppm were developed for benzene detection. Other innovative bioassay, called bio-report systems, were proposed. They use a whole cell (Pseudomona putida or Escherichia coli) as molecular recognition element and exhibit a LOD of about 10 μM. Here, we report on the design of a highly sensitive fluorescence assay for monitoring atmospheric level of benzene. For this purpose, we used as molecular recognition element the porcine odorant-binding protein (pOBP). 1-Aminoanthracene was selected as extrinsic fluorescence probe for designing a competitive fluorescence resonance energy transfer (FRET) assay for benzene detection. The detection limit of our assay was 3.9μg/m3, a value lower than the actual emission limit value of benzene as regulated by European law.
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Affiliation(s)
- Alessandro Capo
- Institute of Food Science, Consiglio Nazionale delle Ricerche, Avellino, Italy
| | - Angela Pennacchio
- Institute of Food Science, Consiglio Nazionale delle Ricerche, Avellino, Italy
| | - Antonio Varriale
- Institute of Food Science, Consiglio Nazionale delle Ricerche, Avellino, Italy
| | - Sabato D'Auria
- Institute of Food Science, Consiglio Nazionale delle Ricerche, Avellino, Italy
| | - Maria Staiano
- Institute of Food Science, Consiglio Nazionale delle Ricerche, Avellino, Italy
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4
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YAN S, LI A, ZHENG H, LUO M, XING X. Effects of Ionic Surfactants on Bacterial Luciferase and α-Amylase. Chin J Chem Eng 2009. [DOI: 10.1016/s1004-9541(08)60283-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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5
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El-Said WA, Yea CH, Kim H, Oh BK, Choi JW. Cell-based chip for the detection of anticancer effect on HeLa cells using cyclic voltammetry. Biosens Bioelectron 2009; 24:1259-65. [DOI: 10.1016/j.bios.2008.07.037] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Revised: 07/11/2008] [Accepted: 07/16/2008] [Indexed: 11/16/2022]
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6
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Yeni F, Odaci D, Timur S. Use of Eggshell Membrane as an Immobilization Platform in Microbial Sensing. ANAL LETT 2008. [DOI: 10.1080/00032710802363594] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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7
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Brenner K, You L, Arnold FH. Engineering microbial consortia: a new frontier in synthetic biology. Trends Biotechnol 2008; 26:483-9. [PMID: 18675483 DOI: 10.1016/j.tibtech.2008.05.004] [Citation(s) in RCA: 518] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2008] [Revised: 05/22/2008] [Accepted: 05/23/2008] [Indexed: 01/27/2023]
Abstract
Microbial consortia are ubiquitous in nature and are implicated in processes of great importance to humans, from environmental remediation and wastewater treatment to assistance in food digestion. Synthetic biologists are honing their ability to program the behavior of individual microbial populations, forcing the microbes to focus on specific applications, such as the production of drugs and fuels. Given that microbial consortia can perform even more complicated tasks and endure more changeable environments than monocultures can, they represent an important new frontier for synthetic biology. Here, we review recent efforts to engineer synthetic microbial consortia, and we suggest future applications.
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Affiliation(s)
- Katie Brenner
- Division of Chemistry and Chemical Engineering, California Institute of Technology 210-41, Pasadena, CA 91125, USA
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8
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Bettaieb F, Ponsonnet L, Lejeune P, Ouada HB, Martelet C, Bakhrouf A, Jaffrézic-Renault N, Othmane A. Immobilization of E. coli bacteria in three-dimensional matrices for ISFET biosensor design. Bioelectrochemistry 2007; 71:118-25. [PMID: 17398167 DOI: 10.1016/j.bioelechem.2007.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Revised: 02/17/2007] [Accepted: 02/19/2007] [Indexed: 11/22/2022]
Abstract
In recent years, cell-based biosensors (CBBs) have been very useful in biomedicine, food industry, environmental monitoring and pharmaceutical screening. They constitute an economical substitute for enzymatic biosensors, but cell immobilization remains a limitation in this technology. To investigate into the potential applications of cell-based biosensors, we describe an electrochemical system based on a microbial biosensor using an Escherichia coli K-12 derivative as a primary transducer to detect biologically active agents. pH variations were recorded by an ion-sensitive field effect transistor (ISFET) sensor on bacteria immobilized in agarose gels. The ISFET device was directly introduced in 100 ml of this mixture or in a miniaturized system using a dialysis membrane that contains 1 ml of the same mixture. The bacterial activity could be detected for several days. The extracellular acidification rate (ECAR) was analyzed with or without the addition of a culture medium or an antibiotic solution. At first, the microorganisms acidified their micro-environment and then they alkalinized it. These two phases were attributed to an apparent substrate preference of bacteria. Cell treatment with an inhibitor or an activator of their metabolism was then monitored and streptomycin effect was tested.
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Affiliation(s)
- F Bettaieb
- CEGELY, UMR-CNRS 5005, Ecole Centrale de Lyon, 69134 Ecully Cedex, France
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9
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Ron EZ. Biosensing environmental pollution. Curr Opin Biotechnol 2007; 18:252-6. [PMID: 17532203 DOI: 10.1016/j.copbio.2007.05.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2007] [Revised: 04/09/2007] [Accepted: 05/11/2007] [Indexed: 11/18/2022]
Abstract
Whole-cell biosensors are finding increasing use for the detection of environmental pollution and toxicity. These biosensors are constructed through the fusion of promoters, responsive to the relevant environmental conditions, to easily monitored reporter genes. Depending on the choice of reporter gene, expression can be monitored by the production of colour, light, fluorescence or electrochemical reactions. Recent advances in this area have included the development of biosensors of compact size that enable the on-line and in situ monitoring of a large number of environmental parameters.
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Affiliation(s)
- Eliora Z Ron
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel.
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10
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Du D, Liu S, Chen J, Ju H, Lian H, Li J. Colloidal gold nanoparticle modified carbon paste interface for studies of tumor cell adhesion and viability. Biomaterials 2005; 26:6487-95. [PMID: 15951013 DOI: 10.1016/j.biomaterials.2005.03.048] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2005] [Accepted: 03/29/2005] [Indexed: 11/21/2022]
Abstract
A non-toxic biomimetic interface for immobilization of living cells and electrochemical exogenous effect study of cell viability was constructed by mixing colloidal gold nanoparticles in carbon paste. A new approach to study the effects of anti-tumor drug and other exogenous factors on cell viability was proposed. The nanoparticles were efficient for preserving the activity of immobilized living cells and preventing their leakage from the electrode surface. The immobilized living AsPC-1 cells (pancreatic adenocarcinoma cells derived from ascites) exhibited an irreversible voltammetric response related to the oxidation of guanine. The presence of guanine was verified by liquid chromatography-mass spectrometry. The contents of guanine in cytoplasm of each AsPC-1 and normal pancreatic cell were detected to be 370 and 22amol, respectively. The cytotoxic effect of adriamycin resulted in a decrease in peak current of guanine. The optimal exogenous factors that affected cell viability, including pH, temperature and salt concentration of electrolyte, were just consistent with cell growth conditions in culture. This simple and rapid method could be applied for the electrochemical investigation of exogenous effect and characterization of the viability of living cells.
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Affiliation(s)
- Dan Du
- Key Laboratory of Analytical Chemistry for Life Science (Education Ministry of China), Nanjing University, Nanjing 210093, PR China
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11
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Rensing C, Maier RM. Issues underlying use of biosensors to measure metal bioavailability. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2003; 56:140-147. [PMID: 12915147 DOI: 10.1016/s0147-6513(03)00057-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Heavy metal-mediated toxicity in the environment is dependent on bioavailable metal concentrations both internal and external to microbial cells. Both internal and external metal bioavailability are influenced by multiple factors in the soil environment. External factors include pH, redox potential, ionic strength, organic matter and clay content. The internal bioavailable metal concentration is dependent on both the aforementioned external factors, as well as metal uptake and efflux activities that are specific for each microorganism. The metal-specific biosensors discussed in this article can be used to measure internal metal bioavailability.
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Affiliation(s)
- Christopher Rensing
- Department of Soil, Water, and Environmental Science, University of Arizona, Room 429, Shantz Boulevard # 38, Tucson, AZ 85721, USA.
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12
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Watanabe K, Hamamura N. Molecular and physiological approaches to understanding the ecology of pollutant degradation. Curr Opin Biotechnol 2003; 14:289-95. [PMID: 12849782 DOI: 10.1016/s0958-1669(03)00059-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Pollutant biodegradation in the environment occurs in the context of various interactions among microorganisms. To understand this ecological process, identification of functionally important populations is considered to be the primary step, which can be followed by isolation and laboratory pure-culture studies of the important organisms. Laboratory studies can then proceed to the analysis of in situ activity and interactions with other organisms. Such studies will shape a deeper understanding of the ecology of pollutant degradation and facilitate the development of new bioremediation strategies.
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Affiliation(s)
- Kazuya Watanabe
- Laboratory of Applied Microbiology, Marine Biotechnology Institute, 3-75-1 Heita, Kamaishi, Iwate 026-0001, Japan.
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13
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Tanaka T, Xing XH, Matsumoto K, Unno H. Preparation and characteristics of resting cells of bioluminescent Pseudomonas putida BLU. Biochem Eng J 2002. [DOI: 10.1016/s1369-703x(02)00036-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Smith CB, Anderson JE, Fischer RL, Webb SR. Stability of green fluorescent protein using luminescence spectroscopy: is GFP applicable to field analysis of contaminants? ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2002; 120:517-520. [PMID: 12442776 DOI: 10.1016/s0269-7491(02)00227-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Green fluorescent protein (GFP) was first isolated in the early 1970s for experimental use from coelenterates or the Pacific jellyfish. Aequorea victoria (Morin and Hastings, 1971). GFP has since become a favored biomarker in the photophysical analysis of molecular and cell biology because of its strong intrinsic visible fluorescence and the feasibility of fusing it to other proteins without affecting their normal functions (Creemers et al., 2000). Here we report using Bacillus subtilis expressing GFP to evaluate the influence of different environmental pH conditions on GFP fluorescence. Emission acquisitions were configured to excite at 471 nm and detect at an emission from 490 to 650 nm at 1-nm increments. Fluorescence intensity was significantly better at pH 7 (4.2 x 105 cps; P-value < 0.01) than at acid or alkaline conditions. GFP is a good biomarker for environments near netural conditions: however, GFP may be unsuitable where soils or waters are below or above pH 7 because of loss in fluorescence intensity. Alternative fluorescent markers and delivery systems must be examined in different environments to optimize responses from bioreporter molecules.
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Affiliation(s)
- C B Smith
- US Army ERDC Topographic Engineering Center, Alexandria, VA 22315, USA.
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15
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Abstract
A microbial biosensor consists of a transducer in conjunction with immobilised viable or non-viable microbial cells. Non-viable cells obtained after permeabilisation or whole cells containing periplasmic enzymes have mostly been used as an economical substitute for enzymes. Viable cells make use of the respiratory and metabolic functions of the cell, the analyte to be monitored being either a substrate or an inhibitor of these processes. Bioluminescence-based microbial biosensors have also been developed using genetically engineered microorganisms constructed by fusing the lux gene with an inducible gene promoter for toxicity and bioavailability testing. In this review, some of the recent trends in microbial biosensors with reference to the advantages and limitations are been discussed. Some of the recent applications of microbial biosensors in environmental monitoring and for use in food, fermentation and allied fields have been reviewed. Prospective future microbial biosensor designs have also been identified.
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Affiliation(s)
- S F D'Souza
- Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
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16
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Miller WG, Brandl MT, Quiñones B, Lindow SE. Biological sensor for sucrose availability: relative sensitivities of various reporter genes. Appl Environ Microbiol 2001; 67:1308-17. [PMID: 11229926 PMCID: PMC92729 DOI: 10.1128/aem.67.3.1308-1317.2001] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A set of three sucrose-regulated transcriptional fusions was constructed. Fusions p61RYTIR, p61RYlac, and p61RYice contain the scrR sucrose repressor gene and the promoterless gfp, lacZ, and inaZ reporter genes, respectively, fused to the scrY promoter from Salmonella enterica serovar Typhimurium. Cells of Erwinia herbicola containing these fusions are induced only in media amended with sucrose, fructose, or sorbose. While a large variation in sucrose-dependent reporter gene activity was observed in cells harboring all gene fusions, fusions to the inaZ reporter gene yielded a much wider range of activity and were responsive to lower levels of sucrose than either lacZ or gfp. The lacZ reporter gene was found to be more efficient than gfp, requiring approximately 300-fold fewer cells for a detectable response over all concentrations of sucrose. Similarly, inaZ was found to be more efficient than lacZ, requiring 30-fold fewer cells at 1.45 microM sucrose and 6,100-fold fewer cells at 29 mM sucrose for a quantifiable response. The fluorescence of individual cells containing p61RYTIR was quantified following epifluorescence microscopy in order to relate the fluorescence exhibited by populations of cells in batch cultures with that of individual cells in such cultures. While the mean fluorescence intensity of a population of individual cells increased with increasing concentrations of sucrose, a wide range of fluorescence intensity was seen among individual cells. For most cultures the distribution of fluorescence intensity among individual cells was log-normally distributed, but cells grown in intermediate concentrations of sucrose exhibited two distinct populations of cells, one having relatively low fluorescence and another with much higher fluorescence. When cells were inoculated onto bean leaves, whole-cell ice nucleation and gfp-based biological sensors for sucrose each indicated that the average concentration of sucrose on moist leaf surfaces was about 20 microM. Importantly, the variation in green fluorescent protein fluorescence of biosensor cells on leaves suggested that large spatial variations in sugar availability occur on leaves.
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Affiliation(s)
- W G Miller
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA
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18
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Abstract
This review surveys the most important and promising contributions of agricultural biotechnology to the development of sustainable, environment-friendly agriculture. It deals with the recent achievements of genetic technology for the development of new transgenic microbial, plant and animal products. It also deals with the newest developments and perspectives of microbial intervention in agricultural practices, such as biofertilizers, biocontrol agents, and various microbiological products used in modern agriculture. The review surveys the outlook for a waste-free, environment-friendly sustainable agricultural practice, including waste management, recycling and bioremediation technologies. The review lists the most important marketable agrobiotechnological products, and their present and projected sales volume.
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Affiliation(s)
- R P Tengerdy
- Department of Microbiology, Colorado State University, Fort Collins 80523, USA
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19
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Billard P, DuBow MS. Bioluminescence-based assays for detection and characterization of bacteria and chemicals in clinical laboratories. Clin Biochem 1998; 31:1-14. [PMID: 9559218 DOI: 10.1016/s0009-9120(97)00136-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES To survey recent advances in the application of bioluminescence to public health problems. The usefulness of bacterial (lux) and eucaryotic (luc) luciferase genes is presented, along with several examples that demonstrate their value as "reporters" of many endpoints of clinical concern. CONCLUSIONS The development of new technologies for monitoring biological and chemical contaminants is in continuous progress. Recent excitement in this area has come from the use of genes encoding enzymes for bioluminescence as reporter systems. Applications of the recombinant luciferase reporter phage concept now provide a sensitive approach for bacterial detection, their viability, and sensitivity to antimicrobial agents. Moreover, a number of fusions of the lux and luc genes to stress inducible genes in different bacteria can allow a real-time measurement of gene expression and determination of cellular viability, and also constitute a new tool to detect toxic chemicals and their bioavailability.
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Affiliation(s)
- P Billard
- Centre des Sciences de l'Environnement, Université de Metz, France
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20
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Abstract
Biosensors utilize biological components to provide selectivity for monitoring compounds of environmental, clinical and industrial importance. A number of biosensors based on bacteria have recently been developed for monitoring toxic metals in the environment. The advantages and disadvantages of these types of biosensors are discussed.
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Affiliation(s)
- S Ramanathan
- Department of Chemistry, University of Kentucky, Lexington 40506-0055, USA
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21
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Barkay T, Gillman M, Turner RR. Effects of dissolved organic carbon and salinity on bioavailability of mercury. Appl Environ Microbiol 1997; 63:4267-71. [PMID: 9361413 PMCID: PMC168746 DOI: 10.1128/aem.63.11.4267-4271.1997] [Citation(s) in RCA: 192] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Hypotheses that dissolved organic carbon (DOC) and electrochemical charge affect the rate of methylmercury [CH3Hg(I)] synthesis by modulating the availability of ionic mercury [Hg(II)] to bacteria were tested by using a mer-lux bioindicator (O. Selifonova, R. Burlage, and T. Barkay, Appl. Environ. Microbiol. 59:3083-3090, 1993). A decline in Hg(II)-dependent light production was observed in the presence of increasing concentrations of DOC, and this decline was more pronounced at pH 7 than at pH 5, suggesting that DOC is a factor controlling the bioavailability of Hg(II). A thermodynamic model (MINTEQA2) was used to select assay conditions that clearly distinguished among various Hg(II) species. By using this approach, it was shown that negatively charged forms of mercuric chloride (HgCl3-/HgCl(4)2-) induced less light production than the electrochemically neutral form (HgCl2), and no difference was observed between the two neutral forms, HgCl2 and Hg(OH)2. These results suggest that the negative charge of Hg(II) species reduces their availability to bacteria and may be one reason why accumulation of CH3Hg(I) is more often reported to occur in freshwater than in estuarine and marine biota.
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Affiliation(s)
- T Barkay
- Gulf Ecology Division, National Health and Environmental Effects Laboratory, U.S. Environmental Protection Agency, Gulf Breeze, Florida 32561, USA.
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22
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Loper JE, Henkels MD. Availability of iron to Pseudomonas fluorescens in rhizosphere and bulk soil evaluated with an ice nucleation reporter gene. Appl Environ Microbiol 1997; 63:99-105. [PMID: 8979343 PMCID: PMC168306 DOI: 10.1128/aem.63.1.99-105.1997] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The biological availability of iron in the rhizosphere was assessed by evaluating ice nucleation activity (INA) expressed in situ by Pseudomonas fluorescens Pf-5 containing a transcriptional fusion (pvd-inaZ) of an iron-regulated promoter to an ice nucleation reporter gene (inaZ). Pf-5 containing pvd-inaZ expresses INA that is inversely related to the iron availability of a growth medium (J. E. Loper and S. E. Lindow, Appl. Environ. Microbiol. 60:1934-1941, 1994). INA expressed by rhizosphere populations of Pf-5 containing pvd-inaZ was at a maximum within 12 to 24 h following inoculation of the bacterium onto bean roots and typically decreased gradually during the following 4 days. Iron availability in the soil, which was altered by the addition of chelators, influenced INA expressed by rhizosphere populations of Pf-5 containing pvd-inaZ. In soil adjusted to a pH of 7.0 or 8.0 by adding Ca(OH)2, rhizosphere populations of Pf-5 containing pvd-inaZ expressed greater INA, indicating lower iron availability, than they did in the nonamended soil at a pH of 5.4. Similarly, rhizosphere populations of Pf-5 containing pvd-inaZ expressed less INA in an agricultural soil of pH 5.4 than in other agricultural soils ranging in pH from 6.4 to 7.7. These results conform to the predictions of chemical models stating that pH is a major factor influencing iron availability in soil solutions. The results of this study indicate that P. fluorescens Pf-5 encountered an iron-limited environment immediately after it was inoculated onto bean roots planted in agricultural field soils. One to two days after the bacterium was inoculated onto root surfaces, however, iron became more available to rhizosphere populations of Pf-5. We speculate that iron acquisition systems of plants and other rhizosphere organisms may provide available sources of iron to established rhizosphere populations of P. fluorescens.
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Affiliation(s)
- J E Loper
- Horticultural Crops Research Laboratory, U.S. Department of Agriculture, Corvallis, Oregon 97330, USA.
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23
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Die biolumineszenz von tieren, pflanzen und bakterien grundlagen und anwendung. Naturwissenschaften 1996. [DOI: 10.1007/bf01152212] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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