scholarly journals Intra-colony channel morphology in Escherichia coli biofilms is governed by nutrient availability and substrate stiffness

2021 ◽  
Author(s):  
Beatrice Bottura ◽  
Liam M Rooney ◽  
Paul A Hoskisson ◽  
Gail McConnell
Keyword(s):  
Escherichia Coli ◽  
Nutrient Availability ◽  
Radial Distance ◽  
Channel Morphology ◽  
Substrate Stiffness ◽  
Nutrient Concentrations ◽  
Channel Formation ◽  
E Coli ◽  
Channel Density ◽  
Quantitative Image

Nutrient-transporting channels are found throughout mature Escherichia coli biofilms, however the influence of environmental conditions on intra-colony channel formation is poorly understood. We report the effect of different substrate nutrient concentrations and agar stiffness on the structure and distribution of intra-colony channels in mature E. coli colony biofilms using fluorescence mesoscopy and quantitative image analysis. Intra-colony channel width was observed to increase non-linearly with radial distance from the centre of the biofilm and channels were, on average, 50% wider at the centre of carbon-limited biofilms compared to nitrogen-limited biofilms. Channel density also differed in colonies grown on rich and minimal medium substrates, with the former creating a network of tightly packed channels and the latter leading to well-separated, wider channels with easily identifiable edges. We conclude that intra-colony channel morphology in E. coli biofilms is influenced by both substrate composition and nutrient availability.

relA Gene control of bacterial glycogen synthesis

1978 ◽  
Vol 56 (6) ◽  
pp. 403-406 ◽  
Author(s):  
William A. Bridger ◽  
William Paranchych
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Stationary Phase ◽  
Nutrient Availability ◽  
Glycogen Content ◽  
Glycogen Synthesis ◽  
Gene Control ◽  
E Coli ◽  
Stimulation Of ◽  
In Cells

Starvation of Escherichia coli K12 for an amino acid results in the stimulation of bacterial glycogen synthesis in cells containing the relA+ gene, but not in cells carrying the relA− allele. Similarly, a large difference in glycogen content is demonstrable between relA+ and relA− cells in stationary phase. It is concluded that guanosine 5′,3′-bis(diphosphate) (ppGpp) or some related relA -dependent metabolite is involved in the regulation of bacterial glycogen synthesis. Detection of significant basal levels of glycogen in a relA− strain of E. coli and in unstarved relA+E. coli indicates that relA control is not absolutely required for glycogen synthesis but serves as a signal for modulation in response to nutrient availability.

Attachment and Biofilm Formation by Escherichia coli O157:H7 on Stainless Steel as Influenced by Exopolysaccharide Production, Nutrient Availability, and Temperature

2004 ◽  
Vol 67 (10) ◽  
pp. 2123-2131 ◽  
Author(s):  
JEE-HOON RYU ◽  
HOIKYUNG KIM ◽  
LARRY R. BEUCHAT
Keyword(s):  
Escherichia Coli ◽  
Stainless Steel ◽  
Nutrient Availability ◽  
Biofilm Formation ◽  
Escherichia Coli O157 ◽  
Strain Atcc ◽  
Wild Type ◽  
E Coli ◽  
Nutrient Environment ◽  
Phosphate Buffered Saline

The influence of exopolysaccharide (EPS) production, nutrient availability, and temperature on attachment and biofilm formation by Escherichia coli O157:H7 strains ATCC 43895 (wild type) and 43895-EPS (extensive EPS-producing mutant) on stainless steel coupons (SSCs) was investigated. Cells grown on heated lettuce juice agar and modified tryptic soy agar were suspended in phosphate-buffered saline (PBS). SSCs were immersed in the cell suspension (109 CFU/ml) at 4°C for 24 h. Biofilm formation by cells attached to SSCs as affected by immersing in 10% tryptic soy broth (TSB), lettuce juice broth (LJB), and minimal salts broth (MSB) at 12 and 22°C was studied. A significantly lower number of strain 43895-EPS cells, compared to strain ATCC 43895 cells, attached to SSCs during a 24-h incubation (4°C) period in PBS suspension. Neither strain formed a biofilm on SSCs subsequently immersed in 10% TSB or LJB, but both strains formed biofilms in MSB. Populations of attached cells and planktonic cells of strain ATCC 43895 gradually decreased during incubation for 6 days in LJB at 22°C, but populations of strain 43895-EPS remained constant for 6 days at 22°C, indicating that the EPS-producing mutant, compared to the wild-type strain, has a higher tolerance to the low-nutrient environment presented by LJB. It is concluded that EPS production by E. coli O157:H7 inhibits attachment to SSCs and that reduced nutrient availability enhances biofilm formation. Biofilms formed under conditions favorable for EPS production may protect E. coli O157:H7 against sanitizers used to decontaminate lettuce and produce processing environments. Studies are under way to test this hypothesis.

scholarly journals NirD curtails the stringent response by inhibiting RelA activity in Escherichia coli

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Loïc Léger ◽  
Deborah Byrne ◽  
Paul Guiraud ◽  
Elsa Germain ◽  
Etienne Maisonneuve
Keyword(s):  
Escherichia Coli ◽  
Nutrient Availability ◽  
Stringent Response ◽  
In Vitro Studies ◽  
E Coli ◽  
Adverse Conditions ◽  
Catalytic Domains ◽  
Intracellular Activities

Bacteria regulate their metabolism to adapt and survive adverse conditions, in particular to stressful downshifts in nutrient availability. These shifts trigger the so-called stringent response, coordinated by the signaling molecules guanosine tetra and pentaphosphate collectively referred to as (p)ppGpp. In Escherichia coli, accumulation of theses alarmones depends on the (p)ppGpp synthetase RelA and the bifunctional (p)ppGpp synthetase/hydrolase SpoT. A tight regulation of these intracellular activities is therefore crucial to rapidly adjust the (p)ppGpp levels in response to environmental stresses but also to avoid toxic consequences of (p)ppGpp over-accumulation. In this study, we show that the small protein NirD restrains RelA-dependent accumulation of (p)ppGpp and can inhibit the stringent response in E. coli. Mechanistically, our in vivo and in vitro studies reveal that NirD directly binds the catalytic domains of RelA to balance (p)ppGpp accumulation. Finally, we show that NirD can control RelA activity by directly inhibiting the rate of (p)ppGpp synthesis.

scholarly journals Regulation of cell size in response to nutrient availability by fatty acid biosynthesis in Escherichia coli

2012 ◽  
Vol 109 (38) ◽  
pp. E2561-E2568 ◽  
Author(s):  
Zhizhong Yao ◽  
Rebecca M. Davis ◽  
Roy Kishony ◽  
Daniel Kahne ◽  
Natividad Ruiz
Keyword(s):  
Escherichia Coli ◽  
Fatty Acid ◽  
Cell Size ◽  
Nutrient Availability ◽  
Fatty Acid Biosynthesis ◽  
Specific Cell ◽  
Wild Type ◽  
Acid Biosynthesis ◽  
E Coli ◽  
Rich Media

Cell size varies greatly among different types of cells, but the range in size that a specific cell type can reach is limited. A long-standing question in biology is how cells control their size. Escherichia coli adjusts size and growth rate according to the availability of nutrients so that it grows larger and faster in nutrient-rich media than in nutrient-poor media. Here, we describe how, using classical genetics, we have isolated a remarkably small E. coli mutant that has undergone a 70% reduction in cell volume with respect to wild type. This mutant lacks FabH, an enzyme involved in fatty acid biosynthesis that previously was thought to be essential for the viability of E. coli. We demonstrate that although FabH is not essential in wild-type E. coli, it is essential in cells that are defective in the production of the small-molecule and global regulator ppGpp. Furthermore, we have found that the loss of FabH causes a reduction in the rate of envelope growth and renders cells unable to regulate cell size properly in response to nutrient excess. Therefore we propose a model in which fatty acid biosynthesis plays a central role in regulating the size of E. coli cells in response to nutrient availability.

Effects of Environmental Parameters on the Dual-Species Biofilms Formed by Escherichia coli O157:H7 and Ralstonia insidiosa, a Strong Biofilm Producer Isolated from a Fresh-Cut Produce Processing Plant

2015 ◽  
Vol 78 (1) ◽  
pp. 121-127 ◽  
Author(s):  
NANCY T. LIU ◽  
XIANGWU NOU ◽  
GARY R. BAUCHAN ◽  
CHARLES MURPHY ◽  
ALAN M. LEFCOURT ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Continuous Culture ◽  
Nutrient Availability ◽  
Safety Concern ◽  
Early Stage ◽  
Culture Conditions ◽  
Processing Plant ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Ralstonia Insidiosa

Biofilm-forming bacteria resident to food processing facilities are a food safety concern due to the potential of biofilms to harbor foodborne bacterial pathogens. When cultured together, Ralstonia insidiosa, a strong biofilm former frequently isolated from produce processing environments, has been shown to promote the incorporation of Escherichia coli O157:H7 into dual-species biofilms. In this study, interactions between E. coli O157:H7 and R. insidiosa were examined under different incubating conditions. Under static culture conditions, the incorporation of E. coli O157:H7 into biofilms with R. insidiosa was not significantly affected by either low incubating temperature (10°C) or by limited nutrient availability. Greater enhancement of E. coli O157:H7 incorporation in dual-species biofilms was observed by using a continuous culture system with limited nutrient availability. Under the continuous culture conditions used in this study, E coli O157:H7 cells showed a strong tendency of colocalizing with R. insidiosa on a glass surface at the early stage of biofilm formation. As the biofilms matured, E coli O157:H7 cells were mostly found at the bottom layer of the dual-species biofilms, suggesting an effective protection by R. insidiosa in the mature biofilms.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Visualisation of E. coli ribosomal RNA in situ by electron spectroscopic imaging and image averaging

1992 ◽  
Vol 50 (1) ◽  
pp. 466-467
Author(s):  
Daniel Beniac ◽  
George Harauz
Keyword(s):  
Ribosomal Rna ◽  
Three Dimensional ◽  
Spectroscopic Imaging ◽  
Electron Spectroscopic Imaging ◽  
E Coli ◽  
Microscopical Technique ◽  
Quantitative Image ◽  
Dimensional Reconstruction ◽  
Image Averaging ◽  
Protein Components

The structures of E. coli ribosomes have been extensively probed by electron microscopy of negatively stained and frozen hydrated preparations. Coupled with quantitative image analysis and three dimensional reconstruction, such approaches are worthwhile in defining size, shape, and quaternary organisation. The important question of how the nucleic acid and protein components are arranged with respect to each other remains difficult to answer, however. A microscopical technique that has been proposed to answer this query is electron spectroscopic imaging (ESI), in which scattered electrons with energy losses characteristic of inner shell ionisations are used to form specific elemental maps. Here, we report the use of image sorting and averaging techniques to determine the extent to which a phosphorus map of isolated ribosomal subunits can define the ribosomal RNA (rRNA) distribution within them.

The Influence of Glycosylation on the Catalytic and Fibrinolytic Properties of Pro-Urokinase

1992 ◽  
Vol 68 (05) ◽  
pp. 539-544 ◽  
Author(s):  
Catherine Lenich ◽  
Ralph Pannell ◽  
Jack Henkin ◽  
Victor Gurewich
Keyword(s):  
Escherichia Coli ◽  
Mammalian Cell ◽  
Human Gene ◽  
Culture Media ◽  
Mammalian Cell Culture ◽  
Glycosylation Site ◽  
Clot Lysis ◽  
Cell Culture Media ◽  
E Coli ◽  
The Uk

SummaryWe previously found that human pro-UK expressed in Escherichia coli is more active in fibrinolysis than recombinant human pro-UK obtained from mammalian cell culture media. To determine whether this difference is related to the lack of glycosylation of the E. coli product, we compared the activity of E. coli-derived pro-UK [(-)pro-UK] with that of a glycosylated pro-UK [(+)pro-UK] and of a mutant of pro-UK missing the glycosylation site at Asn-302 [(-) (302) pro-UK]. The latter two pro-UKs were obtained by expression of the human gene in a mammalian cell. The nonglycosylated pro-UKs were activated by plasmin more efficiently (≈2-fold) and were more active in clot lysis (1.5-fold) than the (+)pro-UK. Similarly, the nonglycosylated two-chain derivatives (UKs) were more active against plasminogen and were more rapidly inactivated by plasma inhibitors than the (+)UK.These findings indicate that glycosylation at Asn-302 influences the activity of pro-UK/UK and could be the major factor responsible for the enhanced activity of E. coli-derived pro-UK.

Usefulness of a Multiplex PCR for Detection of Diarrheagenic Escherichia coli in a Diagnostic Microbiology Laboratory Setting

2016 ◽  
Vol 1 (2) ◽  
pp. 38-42 ◽  
Author(s):  
Khairun Nessa ◽  
Dilruba Ahmed ◽  
Johirul Islam ◽  
FM Lutful Kabir ◽  
M Anowar Hossain
Keyword(s):  
Escherichia Coli ◽  
Multiplex Pcr ◽  
Clinical Laboratory ◽  
Proteinase K ◽  
Microbiology Laboratory ◽  
Pcr Assay ◽  
E Coli ◽  
Diarrheagenic Escherichia Coli ◽  
Multiplex Pcr Assay ◽  
Diagnostic Microbiology

A multiplex PCR assay was evaluated for diagnosis of diarrheagenic Escherichia coli in stool samples of patients with diarrhoea submitted to a diagnostic microbiology laboratory. Two procedures of DNA template preparationproteinase K buffer method and the boiling method were evaluated to examine isolates of E. coli from 150 selected diarrhoeal cases. By proteinase K buffer method, 119 strains (79.3%) of E. coli were characterized to various categories by their genes that included 55.5% enteroaggregative E. coli (EAEC), 18.5% enterotoxigenic E. coli (ETEC), 1.7% enteropathogenic E. coli (EPEC), and 0.8% Shiga toxin-producing E. coli (STEC). Although boiling method was less time consuming (<24 hrs) and less costly (<8.0 US $/ per test) but was less efficient in typing E. coli compared to proteinase K method (41.3% vs. 79.3% ; p<0.001). The sensitivity and specificity of boiling method compared to proteinase K method was 48.7% and 87.1% while the positive and negative predictive value was 93.5% and 30.7%, respectively. The majority of pathogenic E. coli were detected in children (78.0%) under five years age with 53.3% under one year, and 68.7% of the children were male. Children under 5 years age were frequently infected with EAEC (71.6%) compared to ETEC (24.3%), EPEC (2.7%) and STEC (1.4%). The multiplex PCR assay could be effectively used as a rapid diagnostic tool for characterization of diarrheagenic E. coli using a single reaction tube in the clinical laboratory setting.Bangladesh J Med Microbiol 2007; 01 (02): 38-42

Sign in / Sign up

Export Citation Format

Share Document