scholarly journals A lux/gfp dual label system for studying attachment and biofilm formation of Enterobacter sakazakii

SURG Journal ◽  
1969 ◽  
Vol 1 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Melanie Thimodo
Keyword(s):  
Metabolic Activity ◽  
Biofilm Formation ◽  
Significant Feature ◽  
The Novel ◽  
Enterobacter Sakazakii ◽  
Reporter System ◽  
Cell Numbers ◽  
Gfp Reporter ◽  
Novel Method ◽  
Biofilm Development

A significant feature of Enterobacter sakazakii is the ability to form biofilms enabling its persistence in manufacturing and neonatal environments, and implicating it as the primary cause of outbreaks of neonatal meningitis. Conventional methods of studying E. sakazakii are time consuming, inaccurate and damaging to cells, preventing further analysis. A novel method for detecting biofilm formation has been utilized that takes advantage of a dual lux/gfp reporter system cloned into cells for simultaneous quantification of bacterial metabolic activity and cell numbers respectively. To evaluate the effectiveness and accuracy of the novel method compared to the conventional method, strains of bacteria were allowed to form biofilms and were measured using both methods. Biofilm formation of E. sakazakii strains over 2 days was measured and peak formation and changes in biofilm development was determined for each strain. The lux reporter was utilized to determine metabolic activity of cells in the biofilm, correlating to biofilm formation, over 3 days. Biofilm formation of strains was measured using both methods and compared to detect trends. This study found that the novel method was effective at detecting changes in metabolic activity of cells in biofilm. Cell numbers were to be simultaneously detected via the gfp reporter but filters with correct detection wavelength were unavailable thus cell numbers were not obtained here. These observations determine that this dual reporter system is a promising tool for monitoring bacteria in situ and for further understanding of biofilm formation.

scholarly journals Listeria monocytogenes EGD-e Biofilms: No Mushrooms but a Network of Knitted Chains

2008 ◽  
Vol 74 (14) ◽  
pp. 4491-4497 ◽  
Author(s):  
Aurélie Rieu ◽  
Romain Briandet ◽  
Olivier Habimana ◽  
Dominique Garmyn ◽  
Jean Guzzo ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Structural Dynamics ◽  
Biofilm Formation ◽  
Laser Scanning ◽  
Reporter System ◽  
Nutrient Flow ◽  
Dynamic Conditions ◽  
Gfp Reporter ◽  
Static Conditions ◽  
Biofilm Development

ABSTRACT Listeria monocytogenes is a food pathogen that can attach on most of the surfaces encountered in the food industry. Biofilms are three-dimensional microbial structures that facilitate the persistence of pathogens on surfaces, their resistance toward antimicrobials, and the final contamination of processed goods. So far, little is known about the structural dynamics of L. monocytogenes biofilm formation and its regulation. The aims of this study were, by combining genetics and time-lapse laser-scanning confocal microscopy (LSCM), (i) to characterize the structural dynamics of L. monocytogenes EGD-e sessile growth in two nutritional environments (with or without a nutrient flow), and (ii) to evaluate the possible role of the L. monocytogenes agr system during biofilm formation by tracking the spatiotemporal fluorescence expression of a green fluorescent protein (GFP) reporter system. In the absence of nutrient flow (static conditions), unstructured biofilms composed of a few layers of cells that covered the substratum were observed. In contrast, when grown under dynamic conditions, L. monocytogenes EGD-e biofilms were highly organized. Indeed, ball-shaped microcolonies were surrounded by a network of knitted chains. The spatiotemporal tracking of fluorescence emitted by the GFP reporter system revealed that agr expression was barely detectable under static conditions, but it progressively increased during 40 h under dynamic conditions. Moreover, spatial analysis revealed that agr was expressed preferentially in cells located outside the microcolonies. Finally, the in-frame deletion of agrA, which encodes a transcriptional regulator, resulted in a decrease in initial adherence without affecting the subsequent biofilm development.

scholarly journals Inhibition ofStreptococcus gordoniiMetabolic Activity in Biofilm by Cranberry Juice High-Molecular-Weight Component

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Jegdish Babu ◽  
Cohen Blair ◽  
Shiloah Jacob ◽  
Ofek Itzhak
Keyword(s):  
Oral Cavity ◽  
Metabolic Activity ◽  
Biofilm Formation ◽  
Plaque Formation ◽  
High Molecular Mass ◽  
Cranberry Juice ◽  
Numerous Species ◽  
Low Concentrations ◽  
High Molecular Weight Component ◽  
Biofilm Development

Previous studies demonstrated that a cranberry high-molecular-mass, nondialyzable material (NDM) can inhibit adhesion of numerous species of bacteria and prevents bacterial coaggregation of bacterial pairs. Bacterial coaggregation leads to plaque formation leading to biofilm development on surfaces of oral cavity. In the present study, we evaluated the effect of low concentrations of NDM onStreptococcus gordoniimetabolic activity and biofilm formation on restorative dental surfaces. We found that the NDM selectively inhibited metabolic activity ofS. gordonii, without affecting bacterial viability. Inhibiting the metabolic activity of bacteria in biofilm may benefit the health of the oral cavity.

Candidemia Candida albicans clusters have higher tendency to form biofilms than singleton genotypes†

2020 ◽  
Vol 58 (7) ◽  
pp. 887-895 ◽  
Author(s):  
Judith Díaz-García ◽  
Maiken C Arendrup ◽  
Rafael Cantón ◽  
Julio García-Rodríguez ◽  
Ana Gómez ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Metabolic Activity ◽  
Crystal Violet ◽  
Biofilm Formation ◽  
Candida Spp ◽  
Biofilm Production ◽  
Hospital Environments ◽  
Marked Variability ◽  
Inert Surfaces ◽  
Biofilm Development

Abstract The capacity of Candida spp. to form biofilms allows them to attach either to living or inert surfaces, promoting their persistence in hospital environments. In a previous study, we reported strain-to-strain variations in Candida spp. biofilm development, suggesting that some genotypes may be greater biofilm formers than others. In this study, we hypothesize that isolates pertaining to clusters may be found more frequently in the environment due to their ability to form biofilms compared to singleton genotypes. Two hundred and thirty-nine Candida spp. isolates (78 clusters) from candidemia patients admitted to 16 hospitals located in different cities and countries—and the same number of singleton genotypes used as controls—were tested in terms of biofilm formation using the crystal violet and the XTT reduction assays. Candida albicans clusters showed higher biofilm formation in comparison to singleton genotypes (P < .01). The biofilms formed by intra-hospital C. albicans clusters showed higher metabolic activity (P < .05). Furthermore, marked variability was found among species and type of cluster. We observed that the higher the number of isolates, the higher the variability of biofilm production by isolates within the cluster, suggesting that the production of biofilm by isolates of the same genotype is quite diverse and does not depend on the type of cluster studied. In conclusion, candidemia Candida spp. clusters—particularly in the case of C. albicans—show significantly more biomass production and metabolic activity than singleton genotypes.

scholarly journals Candida albicans Als3p is required for wild-type biofilm formation on silicone elastomer surfaces

Microbiology ◽  
2006 ◽  
Vol 152 (8) ◽  
pp. 2287-2299 ◽  
Author(s):  
Xiaomin Zhao ◽  
Karla J. Daniels ◽  
Soon-Hwan Oh ◽  
Clayton B. Green ◽  
Kathleen M. Yeater ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Fusion Protein ◽  
Biofilm Formation ◽  
Laser Scanning Microscopy ◽  
Silicone Elastomer ◽  
Reporter Strain ◽  
Wild Type ◽  
Gfp Reporter ◽  
Biofilm Development ◽  
Biofilm Structure

Candida albicans ALS3 encodes a large cell-surface glycoprotein that has adhesive properties. Immunostaining of cultured C. albicans germ tubes showed that Als3p is distributed diffusely across the germ tube surface. Two-photon laser scanning microscopy of model catheter biofilms grown using a PALS3-green fluorescent protein (GFP) reporter strain showed GFP production in hyphae throughout the biofilm structure while biofilms grown using a PTPI1-GFP reporter strain showed GFP in both hyphae and yeast-form cells. Model catheter biofilms formed by an als3Δ/als3Δ strain were weakened structurally and had approximately half the biomass of a wild-type biofilm. Reintegration of a wild-type ALS3 allele restored biofilm mass and wild-type biofilm structure. Production of an Als3p–Agα1p fusion protein under control of the ALS3 promoter in the als3Δ/als3Δ strain restored some of the wild-type biofilm structural features, but not the wild-type biofilm mass. Despite its inability to restore wild-type biofilm mass, the Als3p–Agα1p fusion protein mediated adhesion of the als3Δ/als3Δ C. albicans strain to human buccal epithelial cells (BECs). The adhesive role of the Als3p N-terminal domain was further demonstrated by blocking adhesion of C. albicans to BECs with immunoglobulin reactive against the Als3p N-terminal sequences. Together, these data suggest that portions of Als3p that are important for biofilm formation may be different from those that are important in BEC adhesion, and that Als3p may have multiple functions in biofilm formation. Overexpression of ALS3 in an efg1Δ/efg1Δ strain that was deficient for filamentous growth and biofilm formation resulted in growth of elongated C. albicans cells, even under culture conditions that do not favour filamentation. In the catheter biofilm model, the ALS3 overexpression strain formed biofilm with a mass similar to that of a wild-type control. However, C. albicans cells in the biofilm had yeast-like morphology. This result uncouples the effect of cellular morphology from biofilm formation and underscores the importance of Als3p in biofilm development on silicone elastomer surfaces.

scholarly journals The Novel Two-Component Regulatory System BfiSR Regulates Biofilm Development by Controlling the Small RNA rsmZ through CafA

2010 ◽  
Vol 192 (20) ◽  
pp. 5275-5288 ◽  
Author(s):  
Olga E. Petrova ◽  
Karin Sauer
Keyword(s):  
Biofilm Formation ◽  
Developmental Process ◽  
Regulatory System ◽  
Opportunistic Pathogen ◽  
The Novel ◽  
Wild Type ◽  
Biofilm Growth ◽  
Two Component ◽  
Biofilm Development ◽  
Rnase G

ABSTRACT The formation of biofilms by the opportunistic pathogen Pseudomonas aeruginosa is a developmental process governed by a novel signal transduction system composed of three two-component regulatory systems (TCSs), BfiSR, BfmSR, and MifSR. Here, we show that BfiSR-dependent arrest of biofilm formation coincided with reduced expression of genes involved in virulence, posttranslational/transcriptional modification, and Rhl quorum sensing but increased expression of rhlAB and the small regulatory RNAs rsmYZ. Overexpression of rsmZ, but not rsmY, coincided with impaired biofilm development similar to inactivation of bfiS and retS. We furthermore show that BfiR binds to the 5′ untranslated region of cafA encoding RNase G. Lack of cafA expression coincided with impaired biofilm development and increased rsmYZ levels during biofilm growth compared to the wild type. Overexpression of cafA restored ΔbfiS biofilm formation to wild-type levels and reduced rsmZ abundance. Moreover, inactivation of bfiS resulted in reduced virulence, as revealed by two plant models of infection. This work describes the regulation of a committed biofilm developmental step following attachment by the novel TCS BfiSR through the suppression of sRNA rsmZ via the direct regulation of RNase G in a biofilm-specific manner, thus underscoring the importance of posttranscriptional mechanisms in controlling biofilm development and virulence.

scholarly journals Escherichia coli and its lipopolysaccharide modulate in vitro Candida biofilm formation

2009 ◽  
Vol 58 (12) ◽  
pp. 1623-1631 ◽  
Author(s):  
H. M. H. N. Bandara ◽  
J. Y. Y. Yau ◽  
R. M. Watt ◽  
L. J. Jin ◽  
L. P. Samaranayake
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Cell Activity ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
E Coli ◽  
Cell Numbers ◽  
Cell Counts ◽  
Biofilm Development

Demystification of microbial behaviour in mixed biofilms could have a major impact on our understanding of infectious diseases. The objectives of this study were to evaluate in vitro the interactions of six different Candida species and a Gram-negative coliform, Escherichia coli, in dual-species biofilms, and to assess the effect of E. coli LPS on Candida biofilm formation. A single isolate of E. coli ATCC 25922 and six different species of Candida, Candida albicans ATCC 90028, Candida glabrata ATCC 90030, Candida krusei ATCC 6258, Candida tropicalis ATCC 13803, Candida parapsilosis ATCC 22019 and Candida dubliniensis MYA-646, were studied using a standard biofilm assay. Each Candida species was co-cultured with E. coli on a polystyrene surface and biofilm formation was quantified by a c.f.u. assay. The biofilm was then analysed by Live/Dead staining and fluorescence microscopy (confocal laser-scanning microscopy, CLSM), whilst scanning electron microscopy (SEM) was employed to visualize the biofilm architecture. The effect of E. coli LPS on Candida biofilm cell activity at defined time intervals was assessed with an XTT reduction assay. A significant quantitative reduction in c.f.u. counts of C. tropicalis (after 90 min), C. parapsilosis (after 90 min and 24 h), C. krusei (after 24 h) and C. dubliniensis (after 24 and 48 h) was noted on incubation with E. coli in comparison with their monospecies biofilm counterparts (P <0.05). On the other hand, a simultaneous and significant reduction in E. coli cell numbers occurred on co-culture with C. albicans (after 90 min), and an elevation of E. coli cell numbers followed co-culture with C. tropicalis (after 24 h) and C. dubliniensis (after 24 h and 48 h) (P <0.05). All quantitative findings were confirmed by SEM and CLSM analyses. By SEM observation, dual-species biofilms demonstrated scanty architecture with reduced visible cell counts at all stages of biofilm development, despite profuse growth and dense colonization in their single-species counterparts. Significantly elevated metabolic activity, as assessed by XTT readings, was observed in E. coli LPS-treated C. tropicalis and C. parapsilosis biofilms (after 48 h), whilst this had the opposite effect for C. dubliniensis (after 24 h) (P <0.05). These data indicate that E. coli and Candida species in a mixed-species environment mutually modulate biofilm development, both quantitatively and qualitatively, and that E. coli LPS appears to be a key component in mediating these outcomes.

A novel method for the determination of linting propensity of paper

TAPPI Journal ◽  
2012 ◽  
Vol 11 (10) ◽  
pp. 9-17
Author(s):  
ALESSANDRA GERLI ◽  
LEENDERT C. EIGENBROOD
Keyword(s):  
Ash Content ◽  
The Novel ◽  
Offset Printing ◽  
Excellent Correlation ◽  
End Conditions ◽  
Bottom Side ◽  
Novel Method ◽  
Total Fraction

A novel method was developed for the determination of linting propensity of paper based on printing with an IGT printability tester and image analysis of the printed strips. On average, the total fraction of the surface removed as lint during printing is 0.01%-0.1%. This value is lower than those reported in most laboratory printing tests, and more representative of commercial offset printing applications. Newsprint paper produced on a roll/blade former machine was evaluated for linting propensity using the novel method and also printed on a commercial coldset offset press. Laboratory and commercial printing results matched well, showing that linting was higher for the bottom side of paper than for the top side, and that linting could be reduced on both sides by application of a dry-strength additive. In a second case study, varying wet-end conditions were used on a hybrid former machine to produce four paper reels, with the goal of matching the low linting propensity of the paper produced on a machine with gap former configuration. We found that the retention program, by improving fiber fines retention, substantially reduced the linting propensity of the paper produced on the hybrid former machine. The papers were also printed on a commercial coldset offset press. An excellent correlation was found between the total lint area removed from the bottom side of the paper samples during laboratory printing and lint collected on halftone areas of the first upper printing unit after 45000 copies. Finally, the method was applied to determine the linting propensity of highly filled supercalendered paper produced on a hybrid former machine. In this case, the linting propensity of the bottom side of paper correlated with its ash content.

Adhesion and Growth of Anaerobic Biofilms on Ion Exchange Resins

1986 ◽  
Vol 21 (4) ◽  
pp. 486-495 ◽  
Author(s):  
R.F.G. Selle Sardi ◽  
W. Bulani ◽  
W.L. Cairns ◽  
N. Kosaric
Keyword(s):  
Metabolic Activity ◽  
Cation Binding ◽  
Fatty Acid Substrate ◽  
Anaerobic Reactors ◽  
Initial Adhesion ◽  
Rapid Changes ◽  
Exchange Resins ◽  
Biofilm Development ◽  
First Time ◽  
Acid Substrate

Abstract Ion exchanger beads are explored as aids in accelerating the development of anaerobic biofilms for use in advanced anaerobic reactors. Initial adhesion and subsequent changes in adhesion and growth of anaerobic biofilms (as reflected in total supported biomass and metabolic activity) were monitored on different ion exchangers (strong cation, strong anion and weak anion) over a period of 12 days. Metabolic activity was recorded for the first time in this type of study using ATP biolumininescence assays which allowed monitoring of rapid changes in the biofilm development. Results indicate that the strong cation exchanger is a better overall substratum for anaerobic biofilm development due to its favorable property of dialent cation binding and adsorption of volatile fatty acid substrate for methanogens.

scholarly journals In VitroAnalyses of the Effects of Heparin and Parabens on Candida albicans Biofilms and Planktonic Cells

2011 ◽  
Vol 56 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Marisa H. Miceli ◽  
Stella M. Bernardo ◽  
T. S. Neil Ku ◽  
Carla Walraven ◽  
Samuel A. Lee
Keyword(s):  
Candida Albicans ◽  
Metabolic Activity ◽  
Biofilm Formation ◽  
High Dose ◽  
Dependent Manner ◽  
Planktonic Cells ◽  
Content Type ◽  
Heparin Sodium ◽  
The Individual

ABSTRACTInfections and thromboses are the most common complications associated with central venous catheters. Suggested strategies for prevention and management of these complications include the use of heparin-coated catheters, heparin locks, and antimicrobial lock therapy. However, the effects of heparin onCandida albicansbiofilms and planktonic cells have not been previously studied. Therefore, we sought to determine thein vitroeffect of a heparin sodium preparation (HP) on biofilms and planktonic cells ofC. albicans. Because HP contains two preservatives, methyl paraben (MP) and propyl paraben (PP), these compounds and heparin sodium without preservatives (Pure-H) were also tested individually. The metabolic activity of the mature biofilm after treatment was assessed using XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction and microscopy. Pure-H, MP, and PP caused up to 75, 85, and 60% reductions of metabolic activity of the mature preformedC. albicansbiofilms, respectively. Maximal efficacy against the mature biofilm was observed with HP (up to 90%) compared to the individual compounds (P< 0.0001). Pure-H, MP, and PP each inhibitedC. albicansbiofilm formation up to 90%. A complete inhibition of biofilm formation was observed with HP at 5,000 U/ml and higher. When tested against planktonic cells, each compound inhibited growth in a dose-dependent manner. These data indicated that HP, MP, PP, and Pure-H havein vitroantifungal activity againstC. albicansmature biofilms, formation of biofilms, and planktonic cells. Investigation of high-dose heparin-based strategies (e.g., heparin locks) in combination with traditional antifungal agents for the treatment and/or prevention ofC. albicansbiofilms is warranted.

scholarly journals REMAXINT: a two-mode clustering-based method for statistical inference on two-way interaction

2021 ◽  
Author(s):  
Zaheer Ahmed ◽  
Alberto Cassese ◽  
Gerard van Breukelen ◽  
Jan Schepers
Keyword(s):  
Null Hypothesis ◽  
Type I Error ◽  
Type I ◽  
The Novel ◽  
Simulation Studies ◽  
Test Statistic ◽  
Clustering Model ◽  
Novel Method ◽  
Main Effects ◽  
Empirical Case Studies

AbstractWe present a novel method, REMAXINT, that captures the gist of two-way interaction in row by column (i.e., two-mode) data, with one observation per cell. REMAXINT is a probabilistic two-mode clustering model that yields two-mode partitions with maximal interaction between row and column clusters. For estimation of the parameters of REMAXINT, we maximize a conditional classification likelihood in which the random row (or column) main effects are conditioned out. For testing the null hypothesis of no interaction between row and column clusters, we propose a $$max-F$$ m a x - F test statistic and discuss its properties. We develop a Monte Carlo approach to obtain its sampling distribution under the null hypothesis. We evaluate the performance of the method through simulation studies. Specifically, for selected values of data size and (true) numbers of clusters, we obtain critical values of the $$max-F$$ m a x - F statistic, determine empirical Type I error rate of the proposed inferential procedure and study its power to reject the null hypothesis. Next, we show that the novel method is useful in a variety of applications by presenting two empirical case studies and end with some concluding remarks.

Sign in / Sign up

Export Citation Format

Share Document