Soil wetting state and preferential transport of Escherichia coli in clay soils

2007 ◽  
Vol 87 (1) ◽  
pp. 61-72 ◽  
Author(s):  
L K Tallon ◽  
B C Si ◽  
D. Korber ◽  
X. Guo
Keyword(s):  
Escherichia Coli ◽  
Preferential Flow ◽  
Fluorescent Protein ◽  
Transport Pathways ◽  
Near Surface ◽  
E Coli ◽  
Significant Difference ◽  
Preferential Transport ◽  
Soil Wetting ◽  
Green Fluorescent

Transport of Escherichia coli (E. coli) through soil to drinking and recreational water may pose a serious health risk. The objective of this study was to determine how initial preferred soil wetting state influences the preferential transport of E. coli in a clay soil. A strain of E. coli marked with green fluorescent protein (gfp) was gravity-fed-sprinkler-applied as simulated rainfall to three replicates in different wetting states, along with Cl- and adsorptive dye near Plenty, SK. Canada. After 48 h, a 50 × 50 × 50 cm3 block was excavated to determine the transport pathways. Digital image analysis of horizontal sections provided estimates of dye coverage. Escherichia coli were significantly filtered in the top 10 cm of soil with concentration profiles similar to that of Cl-. Ratios of E. coli to Cl- did not show significant differences among treatments (P < 0.05) and indicated that below 10 cm depth, E. coli and Cl- were preferentially transported along the same pathways with no significant difference between plots. Results show that the majority of E. coli and Cl- were filtered when transported through the discontinuous pores of the near-surface matrix and suggest a saturated layer that controlled infiltration into organized root channels, resulting in preferential flow. Key words: Preferential flow, Escherichia coli, wetting state, Vertisol, conducting areas

Construction and Characterization of Escherichia coli O157:H7 Strains Expressing Firefly Luciferase and Green Fluorescent Protein and Their Use in Survival Studies‡

1997 ◽  
Vol 60 (10) ◽  
pp. 1167-1173 ◽  
Author(s):  
PINA M. FRATAMICO ◽  
MING Y. DENG ◽  
TERENCE P. STROBAUGH ◽  
SAMUEL A. PALUMBO
Keyword(s):  
Escherichia Coli ◽  
Green Fluorescent Protein ◽  
Orange Juice ◽  
Fluorescent Protein ◽  
Plasmid Vector ◽  
Escherichia Coli O157 ◽  
Apple Cider ◽  
E Coli ◽  
Significant Difference ◽  
Green Fluorescent

The firefly (Photinus pyralis) luciferase (luc) gene on plasmid vector pBESTluc and the Aequorea victoria green fluorescent protein (gfp) gene on plasmid vector pGFP were introduced into strains of Escherichia coli O157:H7. The recombinant E. coli strains were indistinguishable from their parent strains in biochemical and immunological assays and in a multiplex PCR reaction. There was no significant difference in the growth kinetics of the luc-bearing recombinants and the parent strains. At 37°C all of the recombinant strains maintained the vectors and expressed luciferase and the green fluorescent protein when grown both with and without antibiotic selection. Individual colonies of luc-bearing E. coli strains were readily luminescent in the dark after being sprayed with a solution of 1 mM beetle luciferin. The recombinants containing pGFP emitted bright green fluorescence when excited with UV light and the addition of any other proteins, substrates, or cofactors was not required. The green fluorescent protein-expressing E. coli O157:H7 strains were used in studies examining the survival of the organism in apple cider and in orange juice. In apple cider the organism declined to undetectable levels in 24 days at refrigeration temperature while in orange juice the strains survived with only small decreases in number during the 24-day sampling period. These recombinant E. coli O157:H7 strains, containing readily identifiable and stable markers, could be useful as positive controls in microbial assays as well as in studies monitoring bacterial survival and the behavior of E. coli O157:H7 in foods and in a food processing environment.

scholarly journals Vibrio cholerae Triggers SOS and Mutagenesis in Response to a Wide Range of Antibiotics: a Route towards Multiresistance

2011 ◽  
Vol 55 (5) ◽  
pp. 2438-2441 ◽  
Author(s):  
Zeynep Baharoglu ◽  
Didier Mazel
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Vibrio Cholerae ◽  
Fluorescent Protein ◽  
Resistance Development ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Green Fluorescent ◽  
Regulated Promoters

ABSTRACTAntibiotic resistance development has been linked to the bacterial SOS stress response. InEscherichia coli, fluoroquinolones are known to induce SOS, whereas other antibiotics, such as aminoglycosides, tetracycline, and chloramphenicol, do not. Here we address whether various antibiotics induce SOS inVibrio cholerae. Reporter green fluorescent protein (GFP) fusions were used to measure the response of SOS-regulated promoters to subinhibitory concentrations of antibiotics. We show that unlike the situation withE. coli, all these antibiotics induce SOS inV. cholerae.

scholarly journals Colonization of Arabidopsis thaliana with Salmonella enterica and Enterohemorrhagic Escherichia coli O157:H7 and Competition by Enterobacter asburiae

2003 ◽  
Vol 69 (8) ◽  
pp. 4915-4926 ◽  
Author(s):  
Michael B. Cooley ◽  
William G. Miller ◽  
Robert E. Mandrell
Keyword(s):  
Escherichia Coli ◽  
Arabidopsis Thaliana ◽  
Salmonella Enterica ◽  
Fluorescent Protein ◽  
Enterohemorrhagic Escherichia Coli ◽  
Plant Responses ◽  
Human Pathogens ◽  
E Coli ◽  
Green Fluorescent ◽  
Enterobacter Asburiae

ABSTRACT Enteric pathogens, such as Salmonella enterica and Escherichia coli O157:H7, have been shown to contaminate fresh produce. Under appropriate conditions, these bacteria will grow on and invade the plant tissue. We have developed Arabidopsis thaliana (thale cress) as a model system with the intention of studying plant responses to human pathogens. Under sterile conditions and at 100% humidity, S. enterica serovar Newport and E. coli O157:H7 grew to 109 CFU g−1 on A. thaliana roots and to 2 × 107 CFU g−1 on shoots. Furthermore, root inoculation led to contamination of the entire plant, indicating that the pathogens are capable of moving on or within the plant in the absence of competition. Inoculation with green fluorescent protein-labeled S. enterica and E. coli O157:H7 showed invasion of the roots at lateral root junctions. Movement was eliminated and invasion decreased when nonmotile mutants of S. enterica were used. Survival of S. enterica serovar Newport and E. coli O157:H7 on soil-grown plants declined as the plants matured, but both pathogens were detectable for at least 21 days. Survival of the pathogen was reduced in unautoclaved soil and amended soil, suggesting competition from indigenous epiphytes from the soil. Enterobacter asburiae was isolated from soil-grown A. thaliana and shown to be effective at suppressing epiphytic growth of both pathogens under gnotobiotic conditions. Seed and chaff harvested from contaminated plants were occasionally contaminated. The rate of recovery of S. enterica and E. coli O157:H7 from seed varied from undetectable to 19% of the seed pools tested, depending on the method of inoculation. Seed contamination by these pathogens was undetectable in the presence of the competitor, Enterobacter asburiae. Sampling of 74 pools of chaff indicated a strong correlation between contamination of the chaff and seed (P = 0.025). This suggested that contamination of the seed occurred directly from contaminated chaff or by invasion of the flower or silique. However, contaminated seeds were not sanitized by extensive washing and chlorine treatment, indicating that some of the bacteria reside in a protected niche on the seed surface or under the seed coat.

A Novel Approach To Investigate the Uptake and Internalization of Escherichia coli O157:H7 in Spinach Cultivated in Soil and Hydroponic Medium†

2009 ◽  
Vol 72 (7) ◽  
pp. 1513-1520 ◽  
Author(s):  
MANAN SHARMA ◽  
DAVID T. INGRAM ◽  
JITENDRA R. PATEL ◽  
PATRICIA D. MILLNER ◽  
XIAOLIN WANG ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Green Fluorescent Protein ◽  
Fluorescent Protein ◽  
Plasmid Vector ◽  
Green Fluorescent Protein Gene ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Novel Approach ◽  
Efficient Uptake ◽  
Green Fluorescent

Internalization of Escherichia coli O157:H7 into spinach plants through root uptake is a potential route of contamination. ATn7-based plasmid vector was used to insert a green fluorescent protein gene into the attTn7 site in the E. coli chromosome. Three green fluorescent protein–labeled E. coli inocula were used: produce outbreak O157:H7 strains RM4407 and RM5279 (inoculum 1), ground beef outbreak O157:H7 strain 86-24h11 (inoculum 2), and commensal strain HS (inoculum 3). These strains were cultivated in fecal slurries and applied at ca. 103 or 107 CFU/g to pasteurized soils in which baby spinach seedlings were planted. No E. coli was recovered by spiral plating from surface-sanitized internal tissues of spinach plants on days 0, 7, 14, 21, and 28. Inoculum 1 survived at significantly higher populations (P &lt; 0.05) in the soil than did inoculum 3 after 14, 21, and 28 days, indicating that produce outbreak strains of E. coli O157:H7 may be less physiologically stressed in soils than are nonpathogenic E. coli isolates. Inoculum 2 applied at ca. 107 CFU/ml to hydroponic medium was consistently recovered by spiral plating from the shoot tissues of spinach plants after 14 days (3.73 log CFU per shoot) and 21 days (4.35 log CFU per shoot). Fluorescent E. coli cells were microscopically observed in root tissues in 23 (21%) of 108 spinach plants grown in inoculated soils. No internalized E. coli was microscopically observed in shoot tissue of plants grown in inoculated soil. These studies do not provide evidence for efficient uptake of E. coli O157:H7 from soil to internal plant tissue.

Microscopic Observation and Processing Validation of Fruit Sanitizing Treatments for the Enhanced Microbiological Safety of Fresh Orange Juice†

2001 ◽  
Vol 64 (3) ◽  
pp. 310-314 ◽  
Author(s):  
STEVEN PAO ◽  
CRAIG L. DAVIS ◽  
MICKEY E. PARISH
Keyword(s):  
Fluorescent Protein ◽  
Citrus Fruit ◽  
Microbial Reduction ◽  
Hot Water ◽  
Near Surface ◽  
E Coli ◽  
Surface Areas ◽  
Orange Fruit ◽  
Green Fluorescent ◽  
The Impact

Studies were conducted to evaluate the infiltration of dye and bacteria into the interior of orange fruit and the impact of possible infiltration on achieving a 5-log microbial reduction during fresh juice processing. Fresh orange fruit were treated at the stem end area with dye and either Salmonella Rubislaw or Escherichia coli strains expressing green fluorescent protein. Microscopic images showed that bacterial contaminants localized at the surface or near surface areas that may be sanitized by surface treatments. Dye infiltration was not a reliable indicator of bacterial penetration in citrus fruit. To quantify the reduction of bacterial contamination, orange fruit were inoculated with E. coli and processed with and without hot water treatments. Greater than 5-log reductions were achieved in juice extracted from fruit immersed in hot water for 1 or 2 min at 80°C, in comparison to the E. coli level detected in the control juice obtained by homogenization of inoculated fruit.

scholarly journals Inhibition of Salmonella Binding to Porcine Intestinal Cells by a Wood-Derived Prebiotic

2020 ◽  
Vol 8 (7) ◽  
pp. 1051 ◽  
Author(s):  
Aleksandar Božić ◽  
Robin C. Anderson ◽  
Tawni L. Crippen ◽  
Christina L. Swaggerty ◽  
Michael E. Hume ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Green Fluorescent Protein ◽  
Fluorescent Protein ◽  
Saccharomyces Boulardii ◽  
Binding Activity ◽  
Intestinal Cells ◽  
E Coli ◽  
Enteric Infections ◽  
Green Fluorescent

Numerous Salmonella enterica serovars can cause disease and contamination of animal-produced foods. Oligosaccharide-rich products capable of blocking pathogen adherence to intestinal mucosa are attractive alternatives to antibiotics as these have potential to prevent enteric infections. Presently, a wood-derived prebiotic composed mainly of glucose-galactose-mannose-xylose oligomers was found to inhibit mannose-sensitive binding of select Salmonella Typhimurium and Escherichia coli strains when reacted with Saccharomyces boulardii. Tests for the ability of the prebiotic to prevent binding of a green fluorescent protein (GFP)-labeled S. Typhimurium to intestinal porcine epithelial cells (IPEC-J2) cultured in vitro revealed that prebiotic-exposed GFP-labeled S. Typhimurium bound > 30% fewer individual IPEC-J2 cells than did GFP-labeled S. Typhimurium having no prebiotic exposure. Quantitatively, 90% fewer prebiotic-exposed GFP-labeled S. Typhimurium cells were bound per individual IPEC-J2 cell compared to non-prebiotic exposed GFP-labeled S. Typhimurium. Comparison of invasiveness of S. Typhimurium DT104 against IPEC-J2 cells revealed greater than a 90% decrease in intracellular recovery of prebiotic-exposed S. Typhimurium DT104 compared to non-exposed controls (averaging 4.4 ± 0.2 log10 CFU/well). These results suggest compounds within the wood-derived prebiotic bound to E. coli and S. Typhimurium-produced adhesions and in the case of S. Typhimurium, this adhesion-binding activity inhibited the binding and invasion of IPEC-J2 cells.

scholarly journals An improved molecular tool for screening bacterial colonies using GFP expression enhanced by a Dictyostelium sequence

BioTechniques ◽  
2020 ◽  
Vol 68 (2) ◽  
pp. 91-95 ◽  
Author(s):  
Tomo Kondo ◽  
Shigehiko Yumura
Keyword(s):  
Escherichia Coli ◽  
Gene Sequence ◽  
Fluorescent Protein ◽  
Gfp Expression ◽  
Magnetospirillum Gryphiswaldense ◽  
E Coli ◽  
Molecular Tool ◽  
Visual Confirmation ◽  
Green Fluorescent ◽  
User Friendly

During molecular cloning, screening bacterial transformants is a time-consuming and labor-intensive process; however, tractable tools that can be applied to various vectors for visual confirmation of desired colonies are limited. Recently, we reported that translational enhancement by a Dictyostelium gene sequence (TED) boosted protein expression even without an expression inducer in Escherichia coli. Here, we demonstrate a generally applicable molecular tool using the expression of green fluorescent protein enhanced by TED. By inserting a module related to TED into the cloning site in advance, we effectively screened E. coli colonies harboring the desired plasmid functions in a prokaryote ( Magnetospirillum gryphiswaldense) or eukaryote ( Dictyostelium discoideum). Thus, our system represents a user-friendly technique for cloning.

scholarly journals Differences in Growth of Salmonella enterica and Escherichia coli O157:H7 on Alfalfa Sprouts

2002 ◽  
Vol 68 (6) ◽  
pp. 3114-3120 ◽  
Author(s):  
A. O. Charkowski ◽  
J. D. Barak ◽  
C. Z. Sarreal ◽  
R. E. Mandrell
Keyword(s):  
Escherichia Coli ◽  
Irrigation Water ◽  
Salmonella Enterica ◽  
Fluorescent Protein ◽  
Human Pathogens ◽  
E Coli ◽  
Inoculum Dose ◽  
Alfalfa Sprouts ◽  
Green Fluorescent ◽  
Alfalfa Seeds

ABSTRACT Sprout producers have recently been faced with several Salmonella enterica and Escherichia coli O157:H7 outbreaks. Many of the outbreaks have been traced to sprout seeds contaminated with low levels of human pathogens. Alfalfa seeds were inoculated with S. enterica and E. coli O157:H7 strains isolated from alfalfa seeds or other environmental sources and sprouted to examine growth of these human pathogens in association with sprouting seeds. S. enterica strains grew an average of 3.7 log10 on sprouting seeds over 2 days, while E. coli O157:H7 strains grew significantly less, an average of 2.3 log10. The initial S. enterica or E. coli O157:H7 inoculum dose and seed-sprouting temperature significantly affected the levels of both S. enterica and E. coli O157:H7 on the sprouts and in the irrigation water, while the frequency of irrigation water replacement affected only the levels of E. coli O157:H7. Colonization of sprouting alfalfa seeds by S. enterica serovar Newport and E. coli O157:H7 strains transformed with a plasmid encoding the green fluorescent protein was examined with fluorescence microscopy. Salmonella serovar Newport colonized both seed coats and sprout roots as aggregates, while E. coli O157:H7 colonized only sprout roots.

scholarly journals Fate of Escherichia coli during Ensiling of Wheat and Corn

2005 ◽  
Vol 71 (9) ◽  
pp. 5163-5170 ◽  
Author(s):  
Y. Chen ◽  
S. Sela ◽  
M. Gamburg ◽  
R. Pinto ◽  
Z. G. Weinberg
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Dry Matter ◽  
Fluorescent Protein ◽  
Rapid Decrease ◽  
Resistance Marker ◽  
Antibiotic Resistance Marker ◽  
E Coli ◽  
Aerobic Stability ◽  
Green Fluorescent

ABSTRACT A recombinant Escherichia coli strain carrying a plasmid with an antibiotic resistance marker and expressing the green fluorescent protein was inoculated at a concentration of 3.8 × 108 CFU/g into direct-cut wheat (348 g of dry matter kg−1), wilted wheat (450 g of dry matter kg−1), and corn (375 g of dry matter kg−1). The forages were ensiled in mini-silos. The treatments included control (no E. coli added), application of tagged E. coli, and delayed sealing of the inoculated wheat. Three silos per treatment were sampled on predetermined dates, and the numbers of E. coli were determined on Chromocult TBX medium with or without kanamycin. Colonies presumptively identified as E. coli were also tested for fluorescence activity. Addition of E. coli at the time of ensiling resulted in a more rapid decrease in the pH but had almost no effect on the chemical composition of the final silages or their aerobic stability. E. coli disappeared from the silages when the pH decreased below 5.0. It persisted longer in silages of wilted wheat, in which the pH declined more slowly. Control silages of all crops also contained bacteria, presumptively identified as E. coli, that were resistant to the antibiotic, which suggests that some epiphytic strains are naturally resistant to antibiotics.

scholarly journals Cytoplasmic Protein Mobility in Osmotically Stressed Escherichia coli

2008 ◽  
Vol 191 (1) ◽  
pp. 231-237 ◽  
Author(s):  
Michael C. Konopka ◽  
Kem A. Sochacki ◽  
Benjamin P. Bratton ◽  
Irina A. Shkel ◽  
M. Thomas Record ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cellular Response ◽  
Fluorescent Protein ◽  
Volume Fraction ◽  
E Coli ◽  
Surprising Effect ◽  
Wide Range ◽  
Underlying Causes ◽  
The Mean ◽  
Green Fluorescent

ABSTRACT Facile diffusion of globular proteins within a cytoplasm that is dense with biopolymers is essential to normal cellular biochemical activity and growth. Remarkably, Escherichia coli grows in minimal medium over a wide range of external osmolalities (0.03 to 1.8 osmol). The mean cytoplasmic biopolymer volume fraction (〈φ〉) for such adapted cells ranges from 0.16 at 0.10 osmol to 0.36 at 1.45 osmol. For cells grown at 0.28 osmol, a similar 〈φ〉 range is obtained by plasmolysis (sudden osmotic upshift) using NaCl or sucrose as the external osmolyte, after which the only available cellular response is passive loss of cytoplasmic water. Here we measure the effective axial diffusion coefficient of green fluorescent protein (D GFP) in the cytoplasm of E. coli cells as a function of 〈φ〉 for both plasmolyzed and adapted cells. For plasmolyzed cells, the median D GFP ( \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(D_{GFP}^{m}\) \end{document} ) decreases by a factor of 70 as 〈φ〉 increases from 0.16 to 0.33. In sharp contrast, for adapted cells, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(D_{GFP}^{m}\) \end{document} decreases only by a factor of 2.1 as 〈φ〉 increases from 0.16 to 0.36. Clearly, GFP diffusion is not determined by 〈φ〉 alone. By comparison with quantitative models, we show that the data cannot be explained by crowding theory. We suggest possible underlying causes of this surprising effect and further experiments that will help choose among competing hypotheses. Recovery of the ability of proteins to diffuse in the cytoplasm after plasmolysis may well be a key determinant of the time scale of the recovery of growth.

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