The Pseudomonas fluorescens SBW25 wrinkly spreader biofilm requires attachment factor, cellulose fibre and LPS interactions to maintain strength and integrity

Microbiology ◽  
2005 ◽  
Vol 151 (9) ◽  
pp. 2829-2839 ◽  
Author(s):  
Andrew J. Spiers ◽  
Paul B. Rainey
Keyword(s):  
Pseudomonas Fluorescens ◽  
Insertion Site ◽  
Cellulose Fibre ◽  
Cellulose Fibres ◽  
Pseudomonas Fluorescens Sbw25 ◽  
Increased Strength ◽  
Biofilm Development ◽  
Air Liquid Interface ◽  
Attachment Factor ◽  
Fibre Matrix

The wrinkly spreader (WS) isolate of Pseudomonas fluorescens SBW25 forms a substantial biofilm at the air–liquid interface. The biofilm is composed of an extracellular partially acetylated cellulose-fibre matrix, and previous mutagenesis of WS with mini-Tn5 had identified both the regulatory and cellulose-biosynthetic operons. One uncharacterized WS mutant, WS-5, still expressed cellulose but produced very weak biofilms. In this work, the mini-Tn5 insertion site in WS-5 has been identified as being immediately upstream of the tol-pal operon. Like Tol-Pal mutants of other Gram-negative bacteria, WS-5 showed a ‘leaky-membrane’ phenotype, including the serendipitous ability to utilize sucrose, increased uptake of the hydrophilic dye propidium iodide, and the loss of lipopolysaccharide (LPS) expression. WS-5 cells were altered in relative hydrophobicity, and showed poorer recruitment and maintenance in the biofilm than WS. The WS-5 biofilm was also less sensitive to chemical interference during development. However, growth rate, cellulose expression and attachment were not significantly different between WS and WS-5. Finally, WS-5 biofilms could be partially complemented with WS-4, a biofilm- and attachment-deficient mutant that expressed LPS, resulting in a mixed biofilm with significantly increased strength. These findings show that a major component of the WS air–liquid biofilm strength results from the interactions between LPS and the cellulose matrix of the biofilm – and that in the WS biofilm, cellulose fibres, attachment factor and LPS are required for biofilm development, strength and integrity.

scholarly journals Test Methods for Fibre/Matrix Adhesion in Cellulose Fibre-Reinforced Thermoplastic Composite Materials: A Critical Review

2020 ◽  
Vol 8 (2) ◽  
pp. 68-129
Author(s):  
J. Müssig ◽  
N. Graupner
Keyword(s):  
Composite Materials ◽  
Cellulose Fibre ◽  
Test Methods ◽  
Test Method ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Cellulose Fibres ◽  
Reinforced Polymers ◽  
Matrix Adhesion ◽  
Fibre Matrix

Due to the increasing discussion about sustainable and CO2-reduced materials, the demand for cellulose-based fibres as a reinforcing component in thermoplastic composites has increased considerably. Knowledge about the possibilities of modifying fibres for improved adhesion to the plastic matrix is essential in this context. The fibre/matrix adhesion in cellulose fibre-reinforced polymers is of considerable importance for the design of composite materials. Unfortunately, there are no standards for many essential methods to determine fibre/matrix adhesion. In this review article, various methods for measuring the interfacial shear strength between fibres and matrix, as an indirect characterisation of adhesion, are presented. Additionally, a brief overview of different methods for surface modification of cellulose fibres to improve the adhesion to a thermoplastic matrix is given. This review focuses on the fact that the parameters for the production of test specimens as well as the test method itself can vary considerably from study to study. Because of this, the comparison of data from different publications is not always possible. Therefore, in this article, the main influencing factors and differences in the methods are presented and discussed. Based on a systematic review and a clear description and discussion of the methods, the reader is given a broad basis for a better understanding of characteristic values for fibre/matrix adhesion.

scholarly journals Protozoan predation drives adaptive divergence in Pseudomonas fluorescens SBW25; ecology meets experimental evolution.

2021 ◽  
Author(s):  
Farhad S. Golzar ◽  
Gayle C. Ferguson ◽  
Heather L Hendrickson
Keyword(s):  
Pseudomonas Fluorescens ◽  
Adaptive Divergence ◽  
Predator Prey ◽  
Solid Media ◽  
Short Period ◽  
Bacterial Mutants ◽  
Evolution Experiment ◽  
Grazing Resistance ◽  
Pseudomonas Fluorescens Sbw25 ◽  
Air Liquid Interface

Protozoan predators can affect the structure of bacterial communities, but investigations of how predation might influence bacterial evolution and antagonistic behaviours are scarce. Here, we performed a 20-day predator-prey evolution experiment on solid media to investigate the effect of continuous protozoan predation on bacterial traits using Pseudomonas fluorescens SBW25 as prey and Naegleria gruberi as an amoeboid predator. We observed the divergence of colony morphotypes coincident with an increase in bacterial grazing resistance and relative prey fitness in selected bacterial isolates. When subjected to these resistant prey, N. gruberi show reduced activity (increased encystment) and limited replication. An investigation of the mutations responsible for predation resistance reveals mutations in wspF and amrZ genes, affecting biofilm formation and motility. The bacterial mutants in the wspF gene successfully colonise the air-liquid interface and produce robust cellulose biofilms that prevent predation. The mutation in the amrZ mutant withstands predation but this variant produces low levels of cellulose and limited swarming motility. Our findings suggest that protozoan predation can profoundly influence the course of genetic and phenotypic evolution in a short period.

scholarly journals Piezo-Sensitive Fabrics from Carbon Black Containing Conductive Cellulose Fibres for Flexible Pressure Sensors

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5150
Author(s):  
Julia Ullrich ◽  
Martin Eisenreich ◽  
Yvonne Zimmermann ◽  
Dominik Mayer ◽  
Nina Koehne ◽  
...  
Keyword(s):  
Carbon Black ◽  
Pressure Sensors ◽  
Cellulose Fibre ◽  
Nonwoven Material ◽  
Regenerated Cellulose ◽  
Textile Processing ◽  
Cellulose Fibres ◽  
Decisive Importance ◽  
Flexible Pressure Sensors ◽  
Regenerated Cellulose Fibres

The design of flexible sensors which can be incorporated in textile structures is of decisive importance for the future development of wearables. In addition to their technical functionality, the materials chosen to construct the sensor should be nontoxic, affordable, and compatible with future recycling. Conductive fibres were produced by incorporation of carbon black into regenerated cellulose fibres. By incorporation of 23 wt.% and 27 wt.% carbon black, the surface resistance of the fibres reduced from 1.3 × 1010 Ω·cm for standard viscose fibres to 2.7 × 103 and 475 Ω·cm, respectively. Fibre tenacity reduced to 30–50% of a standard viscose; however, it was sufficient to allow processing of the material in standard textile operations. A fibre blend of the conductive viscose fibres with polyester fibres was used to produce a needle-punched nonwoven material with piezo-electric properties, which was used as a pressure sensor in the very low pressure range of 400–1000 Pa. The durability of the sensor was demonstrated in repetitive load/relaxation cycles. As a regenerated cellulose fibre, the carbon-black-incorporated cellulose fibre is compatible with standard textile processing operations and, thus, will be of high interest as a functional element in future wearables.

scholarly journals The Role of a P1-Type ATPase from Pseudomonas fluorescens SBW25 in Copper Homeostasis and Plant Colonization

2007 ◽  
Vol 20 (5) ◽  
pp. 581-588 ◽  
Author(s):  
Xue-Xian Zhang ◽  
Paul B. Rainey
Keyword(s):  
Pseudomonas Fluorescens ◽  
Mutant Strain ◽  
Copper Ions ◽  
Biological Significance ◽  
Copper Homeostasis ◽  
Plant Colonization ◽  
Wild Type ◽  
Pseudomonas Fluorescens Sbw25 ◽  
Plant Surfaces

The genome of the plant-colonizing bacterium Pseudomonas fluorescens SBW25 possesses a putative copper-transporting P1-type ATPase (CueA) that is induced on the plant surfaces. Using a chromosomally-integrated cueA-'lacZ fusion, we show that transcription of cueA can be induced (in vitro) by ions of copper, silver, gold, and mercury. To investigate the biological significance of cueA, a nonpolar cueA deletion mutant (SBW25ΔcueA) was constructed. This mutant strain displayed a twofold reduction in its tolerance to copper compared with the wild-type strain; however, no change was observed in the sensitivity of the mutant strain to silver, gold, or mercury ions. To obtain insight into the ecological significance of cueA, the competitive ability of SBW25ΔcueA was determined relative to wild-type SBW25 in three environments (none contained added copper): minimal M9 medium, the root of sugar beet (Beta vulgaris), and the root of pea (Pisum sativum). Results showed that the fitness of SBW25ΔcueA was not different from the wild type in laboratory medium but was compromised in the two plant environments. Taken together, these data demonstrate a functional role for CueA in copper homeostasis and reveal an ecologically significant contribution to bacterial fitness in the plant rhizosphere. They also suggest that copper ions accumulate on plant surfaces.

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