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Chen G, Srinivasa Ranga VP, Mao Y, Chen K, Qiao H. Impact of lux gene insertion on bacterial surface properties and transport. Res Microbiol 2008; 159:145-51. [DOI: 10.1016/j.resmic.2007.11.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2007] [Revised: 10/30/2007] [Accepted: 11/03/2007] [Indexed: 10/22/2022]
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2
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Mwinyihija M, Meharg A, Dawson J, Strachan NJC, Killham K. An ecotoxicological approach to assessing the impact of tanning industry effluent on river health. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2006; 50:316-24. [PMID: 16392017 DOI: 10.1007/s00244-005-1049-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Accepted: 07/27/2005] [Indexed: 05/06/2023]
Abstract
A study was conducted to investigate the sediment health and water quality of the River Sagana, Kenya, as impacted by the local tanning industry. Chemical analysis identified the main chemical pollutants (pentachlorophenols and chromium) while a bioassay addressed pollutant bioavailability. The bioassay, exploiting the luminescence response of a lux marked bacterial biosensor, was coupled to a dehydrogenase and Dapnia magna test to determine toxicity effects on sediments. Results highlighted the toxicity of the tannery effluent to the sediments at the point of discharge (64% of control bioluminescence) with gradual improvement downstream. There was a significant increase in dehydrogenase downstream, with the enzyme activity attaining a peak at 600 m, also indicating a gradual reduction of toxicity. Biological oxygen demand (19.56 mg L(-1)) dissolved oxygen (3.97 mg L(-1)) and high lethal dose value (85%) of D. magna also confirmed an initial stress at the point of discharge and recovery downstream. Optical density of surface water demonstrated an increase in suspended particulates and colour after the discharge point, eventually decreasing beyond 400 m. In conclusion, the study highlighted the importance of understanding the biogeochemistry of river systems impacted by industries discharging effluent into them and the invaluable role of a biosensor-based ecotoxicological approach to address effluent hazards, particularly in relation to river sediments.
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Affiliation(s)
- Mwinyikione Mwinyihija
- School of Biological Sciences, Plant and Soil Sciences, University of Aberdeen, St. Machar Drive, Cruickshank Building, Aberdeen, AB24 3UU, UK.
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3
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Bunker ST, Bates TC, Oliver JD. Effects of temperature on detection of plasmid or chromosomally encoded gfp- and lux-labeled Pseudomonas fluorescens in soil. ACTA ACUST UNITED AC 2005; 3:83-90. [PMID: 15612505 DOI: 10.1051/ebr:2004008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Pseudomonas fluorescens is a normal inhabitant of the soil rhizosphere. The use of genetically altered strains of P. fluorescens in bioremediation has led to the need for effective monitoring of such cells released into the environment. In this study, we present data on the persistence in soil of P. fluorescens harboring gfp (green fluorescent protein) or lux (bioluminescence) genes. Comparisons were made between strains marked chromosomally and strains carrying these markers on a plasmid. Overall effects of plasmid carriage on culturability were also examined. Sterile soil microcosms were inoculated with washed cells to a final concentration of ca. 10(6) CFU.g(-1) and placed at 5, 23, and 35-37 degrees C. Samples were taken periodically and examined for culturability and viability, using the substrate responsiveness assay. Our results indicated no significant loss of culturability at 5 and 23 degrees C for a period of over one year. In contrast, cells of P. fluorescens incubated at 35-37 degrees C entered the viable but nonculturable state within 7 days. All cells labeled with gfp retained fluorescence regardless of culturability, suggesting that the green fluorescent protein can be of value in monitoring the presence of cells following their release to the environment. Because fluorescence was maintained regardless of the cells' physiological state, this protein may also be an indicator of cell viability.
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Affiliation(s)
- Stephen T Bunker
- Department of Biology, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
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4
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Schmidt CS, Agostini F, Leifert C, Killham K, Mullins CE. Influence of Soil Temperature and Matric Potential on Sugar Beet Seedling Colonization and Suppression of Pythium Damping-Off by the Antagonistic Bacteria Pseudomonas fluorescens and Bacillus subtilis. PHYTOPATHOLOGY 2004; 94:351-363. [PMID: 18944111 DOI: 10.1094/phyto.2004.94.4.351] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ABSTRACT Pseudomonas fluorescens B5 and Bacillus subtilis MBI 600 colonized sugar beet seedlings at matric potentials of -7 x 10(3), -140 x 10(3), and -330 x 10(3) Pa and under five temperature regimes ranging from 7 to 35 degrees C, with diurnal fluctuations of 5 to 22 degrees C. No interaction between matric potential and temperature was observed. In situ bioluminescence indicated physiological activity of Pseudomonas fluorescens B5. Colonization of the root at >/=4 cm below the seed decreased at very low matric potential (-330 x 10(3) Pa). Total population size of Pseudomonas fluorescens B5 per seedling was significantly increased at -140 x 10(3) Pa. However, matric potential had no significant effect on the population density of Pseudomonas fluorescens per gram of root fresh weight and did not affect the distribution of the population down the root. Total population size per seedling and downward colonization by Pseudomonas fluorescens B5 were significantly reduced at high temperatures (25 to 35 degrees C). Maximum colonization down the root occurred at intermediate temperature (15 degrees C) at both matric potentials (-7 x 10(3) and -140 x 10(3) Pa). Addition of B. subtilis MBI 600 to the seed had no effect on rhizosphere populations of Pseudomonas fluorescens B5. Populations of B. subtilis MBI 600, which consisted largely of spores, were slightly reduced at lower matric potentials and were not affected by temperature. Survival and dry weight of plants in soils infested with Pythium spp. decreased with increasing soil temperature and matric potential, indicating an increase in disease pressure. However, there was no significant interaction between the two factors. At -330 x 10(3) Pa, soil dryness but not Pythium infection was the limiting factor for plant emergence. At temperatures of 7 to 25 degrees C and matric potentials of -7 x 10(3) to 120 x 10(3) Pa, treatment with Pseudomonas fluorescens B5 increased plant survival and dry weight. At 7 degrees C and -120 x 10(3) Pa, there was almost complete emergence of seeds treated with Pseudomonas fluorescens B5. Antagonistic activity of Pseudomonas fluorescens B5 decreased with increasing soil temperature and decreasing matric potential. At 25 to 35 degrees C and -7 x 10(3) Pa, no effect was observed. In regimes with different day and night temperatures, the maximum (day) temperature was decisive for disease development and antagonistic activity. B. subtilis MBI 600 displayed no significant antagonistic effect against Pythium ultimum and did not influence the performance of Pseudomonas fluorescens B5 in combined inocula.
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Knox OGG, Killham K, Mullins CE, Wilson MJ. Nematode-enhanced microbial colonization of the wheat rhizosphere. FEMS Microbiol Lett 2003; 225:227-33. [PMID: 12951246 DOI: 10.1016/s0378-1097(03)00517-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The mechanisms by which seed-applied bacteria colonize the rhizosphere in the absence of percolating water are poorly understood. Without mass flow, transport of bacteria by growing roots or soil animals, particularly nematodes may be important. We used a sand-based microcosm system to investigate the ability of three species of nematodes (Caenorhabditis elegans, Acrobeloides thornei and a Cruznema sp.) to promote rhizosphere colonization by four strains of beneficial rhizobacteria. In nearly all cases, rhizosphere colonization was substantially increased by the presence of nematodes, irrespective of bacterial or nematode species. Our results suggest that nematodes are important vectors for bacteria rhizosphere colonization in the absence of percolating water.
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Affiliation(s)
- O G G Knox
- School of Biological Sciences, University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen AB24 3UU, Scotland, UK
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6
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Ritchie JM, Campbell GR, Shepherd J, Beaton Y, Jones D, Killham K, Artz RRE. A stable bioluminescent construct of Escherichia coli O157:H7 for hazard assessments of long-term survival in the environment. Appl Environ Microbiol 2003; 69:3359-67. [PMID: 12788737 PMCID: PMC161480 DOI: 10.1128/aem.69.6.3359-3367.2003] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A chromosomally lux-marked (Tn5 luxCDABE) strain of nontoxigenic Escherichia coli O157:H7 was constructed by transposon mutagenesis and shown to have retained the O157, H7, and intimin phenotypes. The survival characteristics of this strain in the experiments performed (soil at -5, -100, and -1,500 kPa matric potential and artificial groundwater) were indistinguishable from the wild-type strain. Evaluation of potential luminescence was found to be a rapid, cheap, and quantitative measure of viable E. coli O157:H7 Tn5 luxCDABE populations in environmental samples. In the survival studies, bioluminescence of the starved populations of E. coli O157:H7 Tn5 luxCDABE could be reactivated to the original levels of light emission, suggesting that these populations remain viable and potentially infective to humans. The attributes of the construct offer a cheap and low-risk substitute to the use of verocytotoxin-producing E. coli O157:H7 in long-term survival studies.
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Affiliation(s)
- Jennifer M Ritchie
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3UU, Scotland, United Kingdom
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7
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Standing D, Meharg AA, Killham K. A tripartite microbial reporter gene system for real-time assays of soil nutrient status. FEMS Microbiol Lett 2003; 220:35-9. [PMID: 12644225 DOI: 10.1016/s0378-1097(03)00057-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Plant-derived carbon is the substrate which drives the rate of microbial assimilation and turnover of nutrients, in particular N and P, within the rhizosphere. To develop a better understanding of rhizosphere dynamics, a tripartite reporter gene system has been developed. We used three lux-marked Pseudomonas fluorescens strains to report on soil (1) assimilable carbon, (2) N-status, and (3) P-status. In vivo studies using soil water, spiked with C, N and P to simulate rhizosphere conditions, showed that the tripartite reporter system can provide real-time assessment of carbon and nutrient status. Good quantitative agreement for bioluminescence output between reference material and soil water samples was found for the C and P reporters. With regard to soil nitrate, the minimum bioavailable concentration was found to be greater than that analytically detectable in soil water. This is the first time that bioavailable soil C, N and P have been quantified using a tripartite reporter gene system.
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Affiliation(s)
- Dominic Standing
- Department of Plant and Soil Science, School of Biological Sciences, University of Aberdeen, Cruickshank Building, St. Machar Drive, Aberdeen AB24 3UU, Scotland, UK.
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8
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Artz RRE, Killham K. Survival of Escherichia coli O157:H7 in private drinking water wells: influences of protozoan grazing and elevated copper concentrations. FEMS Microbiol Lett 2002; 216:117-22. [PMID: 12423762 DOI: 10.1111/j.1574-6968.2002.tb11424.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The survival characteristics of Escherichia coli O157:H7 in private drinking water wells were investigated to assess the potential for human exposure. A non-toxigenic, chromosomally lux-marked strain of E. coli O157:H7 was inoculated into well water from four different sites in the North East of Scotland. These waters differed significantly in their heavy metal contents as well as nutrient and bacterial grazer concentrations. Grazing and other biological factors were studied using filtered (3 and 0.2 microm) and autoclaved water. The survival of E. coli O157:H7 was primarily decreased by elevated copper concentrations. This hypothesis was supported by acute toxicity assay data. In addition, significant protozoan predation effects were observed in untreated water when compared with survival rates in filtered water. The combination of these two factors in particular determines the survival time of the pathogen in a private water well. It therefore appears that wells with higher water quality as assessed using the European Union Drinking Water Directive standards will also allow survival of E. coli O157:H7 for much longer periods.
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Affiliation(s)
- Rebekka R E Artz
- Department of Plant and Soil Science, University of Aberdeen, Scotland, UK.
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9
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Yarwood RR, Rockhold ML, Niemet MR, Selker JS, Bottomley PJ. Noninvasive quantitative measurement of bacterial growth in porous media under unsaturated-flow conditions. Appl Environ Microbiol 2002; 68:3597-605. [PMID: 12089048 PMCID: PMC126793 DOI: 10.1128/aem.68.7.3597-3605.2002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glucose-dependent growth of the luxCDABE reporter bacterium Pseudomonas fluorescens HK44 was monitored noninvasively in quartz sand under unsaturated-flow conditions within a 45- by 56- by 1-cm two-dimensional light transmission chamber. The spatial and temporal development of growth were mapped daily over 7 days by quantifying salicylate-induced bioluminescence. A nonlinear model relating the rate of increase in light emission after salicylate exposure to microbial density successfully predicted growth over 4 orders of magnitude (r(2) = 0.95). Total model-predicted growth agreed with growth calculated from the mass balance of the system by using previously established growth parameters of HK44 (predicted, 1.2 x 10(12) cells; calculated, 1.7 x 10(12) cells). Colonization expanded in all directions from the inoculation region, including upward migration against the liquid flow. Both the daily rate of expansion of the colonized zone and the population density of the first day's growth in each newly colonized region remained relatively constant throughout the experiment. Nonetheless, substantial growth continued to occur on subsequent days in the older regions of the colonized zone. The proportion of daily potential growth that remained within the chamber declined progressively between days 2 and 7 (from 97 to 13%). A densely populated, anoxic region developed in the interior of the colonized zone even though the sand was unsaturated and fresh growth medium continued to flow through the colonized zone. These data illustrate the potential of a light transmission chamber, bioluminescent bacteria, and sensitive digital camera technology to noninvasively study real-time hydrology-microbiology interactions associated with unsaturated flow in porous media.
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Affiliation(s)
- R R Yarwood
- Department of Microbiolog, Oregon State University, Corvallis, OR 97331-3804, USA
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10
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Palomares A, Vázquez M, Rodríguez-Llorente I, Dary M, Caviedes M. Plasmid Transfer Detection in Soil using the Inducible lPR System Fused to Eukaryotic Luciferase Genes. MICROBIAL ECOLOGY 2001; 41:352-359. [PMID: 12032609 DOI: 10.1007/s002480000093] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We report a model system for plasmid transfer analysis using the regulated lambda phage right promoter, lPR, fused to luc and lucOR as reporter genes. We have demonstrated that the systems cI857-lPR::luc and cI857-lPR::lucOR are temperature-inducible in Escherichia coli but not in other Gram-negative bacteria analyzed, enabling detection of luminescence when plasmids were mobilized from E. coli to those Gram-negative backgrounds. Using light for the detection, we have observed plasmid transfer from E. coli harboring RK2 and R388 derived plasmids to Pseudomonas putida KT2440 (co-introduced with donors) and to indigenous microorganisms, in vitro and in nonsterile soil microcosms. The importance of nutrients for an efficient plasmid transfer in nonsterile soil microcosms has been confirmed. When plasmid transfer experiments were carried out into nonsterile soil microcosms, significant populations of indigenous transconjugants arose. This system provides efficient marker genes and avoids the use of antibiotics for the selection of transconjugants.
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Affiliation(s)
- A.J. Palomares
- Departamento de Microbiología, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain
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11
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Unge A, Jansson J. Monitoring Population Size, Activity, and Distribution of gfp-luxAB-Tagged Pseudomonas fluorescens SBW25 during Colonization of Wheat. MICROBIAL ECOLOGY 2001; 41:290-300. [PMID: 12032602 DOI: 10.1007/s002480000047] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2000] [Accepted: 05/03/2000] [Indexed: 05/23/2023]
Abstract
Increasingly, focus has been directed towards the use of microorganisms as biological control agents to combat fungal disease, as an alternative to chemical fungicides. Pseudomonas fluorescens SBW25 is one bacterial strain that has been demonstrated to promote plant growth by biocontrol of pathogenic fungi. To understand the mode of action of this bacterium, information regarding its localization and metabolic activity on plants is important. In this study, a gfp/luxAB-tagged derivative of P. fluorescens SBW25, expressing the green fluorescent protein (GFP) and bacterial luciferase, was monitored during colonization of wheat starting from seed inoculation. Since bacterial luciferase is dependent on cellular energy reserves for phenotypic expression, metabolically active cells were detected using this marker. In contrast, the stable GFP fluorescence phenotype was used to detect the cells independently of their metabolic status. The combination of these two markers enabled P. fluorescens SBW25 cells to be monitored on wheat plants to determine their specific location and metabolic activity. Studies on homogenized wheat plant parts demonstrated that the seed was the preferred location of P. fluorescens SBW25 during the 65-day time period studied, but the leaves and roots were also colonized. Interestingly, the bacteria were also found to be metabolically active on all plant parts examined. In situ localization of P. fluorescens SBW25 using a combination of different microscopic techniques confirmed the preference for the cells to colonize specific regions of the seed. We speculate that the colonization pattern of P. fluorescens SBW25 can be linked to the mechanism of protection of plants from fungal infection.
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Affiliation(s)
- A. Unge
- Department of Biochemistry, Stockholm University, S-10691 Stockholm, Sweden
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12
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Räsänen LA, Elväng AM, Jansson J, Lindström K. Effect of heat stress on cell activity and cell morphology of the tropical rhizobium, Sinorhizobium arboris. FEMS Microbiol Ecol 2001. [DOI: 10.1111/j.1574-6941.2001.tb00777.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Jansson JK, Björklöf K, Elvang AM, Jørgensen KS. Biomarkers for monitoring efficacy of bioremediation by microbial inoculants. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2000; 107:217-223. [PMID: 15092998 DOI: 10.1016/s0269-7491(99)00140-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/1998] [Accepted: 05/22/1999] [Indexed: 05/24/2023]
Abstract
Bioaugmentation of contaminated sites with microbes that are adapted or genetically engineered for degradation of specific toxic compounds is an area that is currently being explored as a clean-up option. Biomarkers have been developed to track the survival and efficacy of specific bacteria that are used as inocula for bioremediation of contaminated soil. Examples of biomarkers include the luc gene, encoding firefly luciferase and the gfp gene, encoding the green fluorescent protein (GFP). The luc gene was used to tag different bacteria used for bioremediation of gasoline or chlorophenols. The bacteria were monitored on the basis of luciferase activity in cell extracts from soil. The gfp gene was also used to monitor bacteria during degradation of chlorophenol in soil, based on fluorescence of the GFP protein. Other biomarkers can also be used for monitoring of microbial inocula used for bioaugmentation of contaminated sites. The choice of biomarker and monitoring system depends on the particular site, bacterial strain and sensitivity and specificity of detection required.
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Affiliation(s)
- J K Jansson
- Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, S-10691 Stockholm, Sweden.
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14
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Neilson JW, Pierce SA, Maier RM. Factors influencing expression of luxCDABE and nah genes in Pseudomonas putida RB1353(NAH7, pUTK9) in dynamic systems. Appl Environ Microbiol 1999; 65:3473-82. [PMID: 10427037 PMCID: PMC91522 DOI: 10.1128/aem.65.8.3473-3482.1999] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bioluminescent reporter organisms have been successfully exploited as analytical tools for in situ determination of bioavailable levels of contaminants in static environmental samples. Continued characterization and development of such reporter systems is needed to extend the application of these bioreporters to in situ monitoring of degradation in dynamic environmental systems. In this study, the naphthalene-degrading, lux bioreporter bacterium Pseudomonas putida RB1353 was used to evaluate the relative influences of cell growth stage, cell density, substrate concentration, oxygen tension, and background carbon substrates on both the magnitude of the light response and the rate of salicylate disappearance. The effect of these variables on the lag time required to obtain maximum luminescence and degradation was also monitored. Strong correlations were observed between the first three factors and both the magnitude and induction time of luminescence and degradation rate. The maximum luminescence response to nonspecific background carbon substrates (soil extract broth or Luria broth) was 50% lower than that generated in response to 1 mg of sodium salicylate liter(-1). Oxygen tension was evaluated over the range of 0.5 to 40 mg liter(-1), with parallel inhibition to luminescence and degradation rate (20 mg of sodium salicylate liter(-1)) observed at 1.5 mg liter(-1) and below and no effect observed above 5 mg liter(-1). Oxygen tensions from 2 to 4 mg liter(-1) influenced the magnitude of luminescence but not the salicylate degradation rate. The results suggest that factors causing parallel shifts in the magnitude of both luminescence and degradation rate were influencing regulation of the nah operon promoters. For factors that cause nonparallel shifts, other regulatory mechanisms are explored. This study demonstrates that lux reporter bacteria can be used to monitor both substrate concentration and metabolic response in dynamic systems. However, each lux reporter system and application will require characterization and calibration.
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Affiliation(s)
- J W Neilson
- Department of Soil, Water, and Environmental Science, University of Arizona, Tucson, Arizona 85721, USA
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15
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Unge A, Tombolini R, Molbak L, Jansson JK. Simultaneous monitoring of cell number and metabolic activity of specific bacterial populations with a dual gfp-luxAB marker system. Appl Environ Microbiol 1999; 65:813-21. [PMID: 9925621 PMCID: PMC91100 DOI: 10.1128/aem.65.2.813-821.1999] [Citation(s) in RCA: 146] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A dual marker system was developed for simultaneous quantification of bacterial cell numbers and their activity with the luxAB and gfp genes, encoding bacterial luciferase and green fluorescent protein (GFP), respectively. The bioluminescence phenotype of the luxAB biomarker is dependent on cellular energy status. Since cellular metabolism requires energy, bioluminescence output is directly related to the metabolic activity of the cells. By contrast, GFP fluorescence has no energy requirement. Therefore, by combining these two biomarkers, total cell number and metabolic activity of a specific marked cell population could be monitored simultaneously. Two different bacterial strains, Escherichia coli DH5alpha and Pseudomonas fluorescens SBW25, were chromosomally tagged with the dual marker cassette, and the cells were monitored under different conditions by flow cytometry, plate counting, and luminometry. During log-phase growth, the luciferase activity was proportional to the number of GFP-fluorescent cells and culturable cells. Upon entrance into stationary phase or during starvation, luciferase activity decreased due to a decrease in cellular metabolic activity of the population, but the number of GFP-fluorescing cells and culturable cells remained relatively stable. In addition, we optimized a procedure for extraction of bacterial cells from soil, allowing GFP-tagged bacteria in soil samples to be quantitated by flow cytometry. After 30 days of incubation of P. fluorescens SBW25::gfp/lux in soil, the cells were still maintained at high population densities, as determined by GFP fluorescence, but there was a slow decline in luciferase activity, implicating nutrient limitation. In conclusion, the dual marker system allowed simultaneous monitoring of the metabolic activity and cell number of a specific bacterial population and is a promising tool for monitoring of specific bacteria in situ in environmental samples.
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Affiliation(s)
- A Unge
- Department of Biochemistry, Stockholm University, S-10691 Stockholm, Sweden
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16
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Jensen LE, Kragelund L, Nybroe O. Expression of a nitrogen regulated lux gene fusion in Pseudomonas fluorescens DF57 studied in pure culture and in soil. FEMS Microbiol Ecol 1998. [DOI: 10.1111/j.1574-6941.1998.tb00457.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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17
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Kragelund L, Hosbond C, Nybroe O. Distribution of metabolic activity and phosphate starvation response of lux-tagged Pseudomonas fluorescens reporter bacteria in the barley rhizosphere. Appl Environ Microbiol 1997; 63:4920-8. [PMID: 9406412 PMCID: PMC168819 DOI: 10.1128/aem.63.12.4920-4928.1997] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The purpose of this study was to determine the metabolic activity of Pseudomonas fluorescens DF57 in the barley rhizosphere and to assess whether sufficient phosphate was available to the bacterium. Hence, two DF57 reporter strains carrying chromosomal luxAB gene fusions were introduced into the rhizosphere. Strain DF57-40E7 expressed luxAB constitutively, making bioluminescence dependent upon the metabolic activity of the cells under defined assay conditions. The DF57-P2 reporter strain responded to phosphate limitation, and the luxAB gene fusion was controlled by a promoter containing regulatory sequences characteristic of members of the phosphate (Pho) regulon. DF57 generally had higher metabolic activity in a gnotobiotic rhizosphere than in the corresponding bulk soil. Within the rhizosphere the distribution of metabolic activity along the root differed between the rhizosphere soil and the rhizoplane, suggesting that growth conditions may differ between these two habitats. The DF57-P2 reporter strain encountered phosphate limitation in a gnotobiotic rhizosphere but not in a natural rhizosphere. This difference in phosphate availability seemed to be due to the indigenous microbial population, as DF57-P2 did not report phosphate limitation when established in the rhizosphere of plants in sterilized soil amended with indigenous microorganisms.
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Affiliation(s)
- L Kragelund
- Department of Ecology and Molecular Biology, Royal Veterinary and Agricultural University, Frederiksberg, Denmark
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18
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Jansson JK, Prosser JI. Quantification of the presence and activity of specific microorganisms in nature. Mol Biotechnol 1997; 7:103-20. [PMID: 9219225 DOI: 10.1007/bf02761746] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Traditional techniques for assessment of microbial numbers and activity generally lack the specificity required for risk assessment following environmental release of genetically engineered microbial inocula. Immunological and molecular-based techniques, such as DNA probing and genetic tagging, were initially used to determine the presence or absence of microorganisms in environmental samples. Increasingly they are being developed for quantification of populations of specific organisms, either indigenous or introduced, in the environment. In addition, they are being used to quantify the activity of particular organisms or groups of organisms, greatly extending the range of techniques available to the microbial ecologist. This article reviews the use of traditional techniques for the quantification of microbial population size and activity and the application of molecular techniques, including DNA probing, genetic marking, use of fluorescent probes, and quantitative PCR, in combination with advanced cell detection techniques such as confocal laser scanning microscopy and flow cytometry.
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Affiliation(s)
- J K Jansson
- Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden.
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19
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Wainwright M, Killham K, Russell C, Grayston SJ. Partial evidence for the existence of mitogenetic radiation. Microbiology (Reading) 1997; 143:1-3. [DOI: 10.1099/00221287-143-1-1-a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Milton Wainwright
- Deapartment of molecular Biology and BiotechnologyUniversity of SheffieldSheffield S10 2UHUK
| | - Kenneth Killham
- Deapartment of Plant and soil ScienceUniversity of AberdeenAberdeen AB9 2UEUK
| | - Charles Russell
- Deapartment of Plant and soil ScienceUniversity of AberdeenAberdeen AB9 2UEUK
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Waterhouse R, Buhariwalla H, Bourn D, Rattray E, Glover L. CCD detection of lux-marked Pseudomonas syringae pv. phaseolicola L-forms associated with Chinese cabbage and the resulting disease protection against Xanthomonas campestris. Lett Appl Microbiol 1996. [DOI: 10.1111/j.1472-765x.1996.tb01157.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Prosser JI, Killham K, Glover LA, Rattray EA. Luminescence-based systems for detection of bacteria in the environment. Crit Rev Biotechnol 1996; 16:157-83. [PMID: 8635199 DOI: 10.3109/07388559609147420] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The development of techniques for detection and tracking of microorganisms in natural environments has been accelerated by the requirement for assessment of the risks associated with environmental release of genetically engineered microbial inocula. Molecular marker systems are particularly appropriate for such studies and luminescence-based markers have the broadest range of applications, involving the introduction of prokaryotic (lux) or eukaryotic (luc) genes for the enzyme luciferase. Lux or luc genes can be detected on the basis of unique DNA sequences by gene probing and PCR amplification, but the major advantage of luminescence-based systems is the ability to detect light emitted by marked organisms or by luciferase activity in cell-free extracts. Luminescent colonies can be detected by eye, providing distinction from colonies of indigenous organisms, and the sensitivity of plate counting can be increased greatly by CCD imaging. Single cells or microcolonies of luminescent organisms can also be detected in environmental samples by CCD image-enhanced microscopy, facilitating study of their spatial distribution. The metabolic activity of luminescence-marked populations can be quantified by luminometry and does not require extraction of cells or laboratory growth. Metabolic activity, and potential activity, of marked organisms therefore can be measured during colonization of soil particles and plant material in real time without disturbing the colonization process. In comparison with traditional activity techniques, luminometry provides significant increases in sensitivity, accuracy, and, most importantly, selectivity, as activity can be measured in the presence of indigenous microbial communities. The sensitivity, speed, and convenience of luminescence measurements make this a powerful technique that is being applied to the study of an increasingly wide range of ecological problems. These include microbial survival and recovery, microbial predation, plant pathogenicity, phylloplane and rhizosphere colonization and reporting of gene expression in environmental samples.
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Affiliation(s)
- J I Prosser
- Department of Molecular and Cell Biology, University of Aberdeen, Marischal College, Scotland
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22
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Wright DA, Killham K, Glover LA, Prosser JI. Role of Pore Size Location in Determining Bacterial Activity during Predation by Protozoa in Soil. Appl Environ Microbiol 1995; 61:3537-43. [PMID: 16535141 PMCID: PMC1388703 DOI: 10.1128/aem.61.10.3537-3543.1995] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The predation of a luminescence-marked strain of Pseudomonas fluorescens by the soil ciliate Colpoda steinii was studied in soil microcosms. Bacterial cells were introduced in either small (neck diameter, <6 (mu)m) or intermediate-sized (neck diameter, 6 to 30 (mu)m) pores in the soil by inoculation at appropriate matric potentials, and ciliates were introduced into large pores (neck diameter, 30 to 60 (mu)m). Viable cell concentrations of bacteria introduced into intermediate-sized pores decreased at a greater rate than those in small pores, with reductions in bacterial populations being accompanied by an increase in viable cell numbers of the ciliate. The data indicate that the location of bacteria in small pores provides significant protection from predation. In the absence of C. steinii, the level of metabolic activity of the bacterial population, measured by luminometry, decreased at a greater rate than cell number, and the level of luminescence cell(sup-1) consequently decreased. The decrease in levels of luminescence indicates a loss of activity due to starvation. During predation by C. steinii, the level of the activity of cells introduced into small pores fell in a similar manner. The level of cell activity was, however, significantly greater for cells introduced into intermediate-sized pores, despite their greater susceptibility to predation. The data suggest that increased activity arises from a release of nutrients by the predator and the greater accessibility of bacteria to nutrients in larger pores. Nutrient amendment of microcosms resulted in increases in bacterial populations to sustained, higher levels, while levels of luminescence increased transiently. The predation of cells introduced into intermediate-sized pores was greater, and there was also evidence that the level of activity of surviving bacteria was greater for bacteria in intermediate-sized but not small pores.
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Ferguson Y, Glover LA, McGillivray DM, Prosser JI. Survival and Activity of lux-Marked Aeromonas salmonicida in Seawater. Appl Environ Microbiol 1995; 61:3494-8. [PMID: 16535133 PMCID: PMC1388587 DOI: 10.1128/aem.61.9.3494-3498.1995] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The fish pathogen Aeromonas salmonicida was chromosomally marked with genes encoding bacterial luciferase, luxAB, isolated from Vibrio fischeri, resulting in constitutive luciferase production. During exponential growth in liquid batch culture, luminescence was directly proportional to biomass concentration, and luminometry provided a lower detection limit of approximately 10(sup3) cells ml(sup-1), 1 order of magnitude more sensitive than enzyme-linked immunosorbent assay detection. In sterile seawater at 4(deg)C, lux-marked A. salmonicida entered a dormant, nonculturable state and population activity decreased rapidly. The activity per viable cell, however, increased by day 4, indicating that a proportion of the population remained active and culturable. Putative dormant cells were not resuscitated after the addition of a range of substrates.
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Rattray EA, Prosser JI, Glover LA, Killham K. Characterization of rhizosphere colonization by luminescent Enterobacter cloacae at the population and single-cell levels. Appl Environ Microbiol 1995; 61:2950-7. [PMID: 7487027 PMCID: PMC167571 DOI: 10.1128/aem.61.8.2950-2957.1995] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
A bioluminescence marker system was used to characterized colonization of the rhizosphere by a bacterial inoculum, both in terms of population activity and at the single-cell level. Plasmid pQF70/44, which contains luxAB genes under the control of a strong constitutive phage promoter, was introduced into the rhizobacterium and model biocontrol agent Enterobacter cloacae. Light output from the lux-modified strain was detected by luminometry of samples from growing cultures of E. cloacae and from inoculated soil and wheat root samples. The minimum detection limits for fully active cells under optimum conditions were 90 and 445 cells g-1 for liquid culture and soil, respectively. The metabolic activities of the lux-marked population of E. cloacae, characterized by luminometry, contrasted in rhizosphere and nonrhizosphere soil. Cells in the rhizosphere were active, and there was a linear relationship between light output and cell concentration. The activity of cells in nonrhizosphere coil could not be detected unless the soil was supplied with substrate. Novel use of a charge-coupled device is reported for the spatial characterization of rhizosphere colonization by E. cloacae (pQF70/44) at the single-cell and population levels. Used macroscopically, the charge-coupled device identified differences in colonization due to competition from indigenous soil organisms. The lux-marked bacterium was able to colonize all depths of roots in the absence of competition but was restricted tot he spermosphere in the presence of competition (nonsterile soil).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- E A Rattray
- Department of Plant and Soil Science, University of Aberdeen, United Kingdom
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Oliver JD, McDougald D, Barrett T, Anne Glover L, Prosser JI. Effect of temperature and plasmid carriage on nonculturability in organisms targeted for release. FEMS Microbiol Ecol 1995. [DOI: 10.1111/j.1574-6941.1995.tb00147.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Brennerova M, Crowley D. Direct detection of rhizosphere-colonizing Pseudomonas sp. using an Escherichia coli rRNA promoter in a Tn7-lux system. FEMS Microbiol Ecol 1994. [DOI: 10.1111/j.1574-6941.1994.tb00117.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Waterhouse RN, Glover LA. CCD-monitoring of bioluminescence during the induction of the cell wall-deficient, L-form state of a genetically modified strain of Pseudomonas syringae pv. phaseolicola. Lett Appl Microbiol 1994; 19:88-91. [PMID: 7765223 DOI: 10.1111/j.1472-765x.1994.tb00912.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Bioluminescence from developing L-form colonies of the plant pathogen, Pseudomonas syringae pv. phaseolicola, was monitored using the enhanced light-detecting capabilities of a charge-coupled device. During L-form induction, the bacteria entered a prolonged period during which the level of light output and hence metabolic activity, was very low. A relatively small number of highly bioluminescent L-form colonies were then observed to develop against a background of non-bioluminescent bacteria. When these colonies were sub-cultured and examined microscopically, typical L-form morphology was observed and continued high bioluminescence was detectable from derived colonies.
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Affiliation(s)
- R N Waterhouse
- Department of Molecular and Cell Biology, University of Aberdeen, Marischal College, UK
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Enrique Vázquez M, Cebolla A, Palomares AJ. Controlled expression of click beetle luciferase using a bacterial operator-repressor system. FEMS Microbiol Lett 1994; 121:11-8. [PMID: 8082821 DOI: 10.1111/j.1574-6968.1994.tb07068.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The bioluminescent phenotype conferred by luciferase genes in a particular bacterium has demonstrated to be one of the most versatile and useful methods to detect microorganisms. Genetic constructions derived from miniTn5 vectors have been constructed for the introduction and stable maintenance of the click beetle luciferase gene, lucOR, in various Gram-negative bacteria. To attenuate the expression in the environment where the marked strain has to survive (and to allow sensitive detection when desired) a DNA fragment containing the repressor gene lacIq and a Ptrc::lucOR fusion was cloned onto a suicide plasmid. This construction is able to express high luciferase levels only when induced by IPTG. Matings between Escherichia coli containing the suicide transposon vector and different recipient bacteria gave transposition frequencies from 10(-7) to 10(-5). Strains with miniTn5-lucOR insertions showed luciferase activity induced by IPTG addition. The stringency of the regulation and the intensity of light emission depended on the tagged strain. This system allows stable maintenance of the marker and tight control of luciferase expression in the environment.
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Affiliation(s)
- M Enrique Vázquez
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, Spain
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Cook N, Silcock DJ, Waterhouse RN, Prosser JI, Glover LA, Killham K. Construction and detection of bioluminescent strains of Bacillus subtilis. THE JOURNAL OF APPLIED BACTERIOLOGY 1993; 75:350-9. [PMID: 8226392 DOI: 10.1111/j.1365-2672.1993.tb02787.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Bioluminescence (lux) genes from Vibrio fischeri and V. harveyi were introduced into Bacillus subtilis on a plasmid vector and by chromosomal integration. The plasmid-bearing strain was highly luminescent and stable under antibiotic selection, but luminescence was lost in the absence of selection and following sporulation and germination. The chromosomally marked strains emitted less light but were found to be stable without the requirement for antibiotic selection and following sporulation and germination. Individual luminescing colonies of both B. subtilis strains could be detected against a high background of non-bioluminescent indigenous soil microbial colonies on agar plates using a charge-coupled device camera. These bioluminescent Gram-positive strains could be of value in studies concerning the survival and spread of genetically-modified micro-organisms in soil environments.
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Affiliation(s)
- N Cook
- Department of Molecular and Cell Biology, Marischal College, University of Aberdeen, UK
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Waterhouse RN, Silcock DJ, White HL, Buhariwalla HK, Glover LA. The cloning and characterization of phage promoters, directing high expression of luciferase in Pseudomonas syringae pv. phaseolicola, allowing single cell and microcolony detection. Mol Ecol 1993; 2:285-93. [PMID: 8162227 DOI: 10.1111/j.1365-294x.1993.tb00021.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Regions of DNA containing promoter sequences from a Pseudomonas syringae pv. phaseolicola-specific phage (phi 11P) were identified by shotgun cloning into a broad-host-range promoter-probe vector (pQF70). When used in conjunction with the luciferase reporter genes, one of these DNA fragments, 19H, directed gene expression at a level which enabled the subsequent light output (bioluminescence) of single cells of P. syringae pv. phaseolicola to be detected and visualized using a charge-coupled device (CCD). The P. syringae pv. phaseolicola phi 11P, 19H and P. aeruginosa phi PLS27, HcM promoters gave a 50-fold increase in bioluminescence (maximum relative light output) compared to similar constructs containing other well-characterized promoters, for example, tetracycline. Similar bioluminescent characteristics of the transformed bacterium, were observed during growth with and without antibiotic-selection. When lux+ bacteria were inoculated onto French bean leaf (Phaseolus vulgaris L.), the resultant secondary halo blight lesions were bioluminescent and during phylloplane colonization by the lux+ bacterium, bioluminescence on leaf surfaces was detected and imaged by the CCD. Use of these newly identified promoters, combined with the greatly increased sensitivity of bioluminescence detection by the CCD, thus provided a new dimension for the study of natural ecological populations during the bacterial colonization of plants.
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Affiliation(s)
- R N Waterhouse
- Department of Molecular and Cell Biology, University of Aberdeen, Scotland, UK
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