Increased intraspecies diversity in Escherichia coli biofilms promotes cellular growth at the expense of matrix production

Intraspecies diversity in biofilm communities is associated with enhanced survival and growth of the individual biofilm populations. Studies on the subject are scarce, namely, when more than three strains are present. Hence, in this study, the influence of intraspecies diversity in biofilm populations composed of up to six different Escherichia coli strains isolated from urine was evaluated in conditions mimicking the ones observed in urinary tract infections and catheter-associated urinary tract infections. In general, with the increasing number of strains in a biofilm, an increase in cell cultivability and a decrease in matrix production were observed. For instance, single-strain biofilms produced an average of 73.1 µg·cm-2 of extracellular polymeric substances (EPS), while six strains biofilms produced 19.9 µg·cm-2. Hence, it appears that increased genotypic diversity in a biofilm leads E. coli to direct energy towards the production of its offspring, in detriment of the production of public goods (i.e., matrix components). Apart from ecological implications, these results can be explored as another strategy to reduce the biofilm burden, as a decrease in EPS matrix production may render these intraspecies biofilms more sensitive to antimicrobial agents.This work was financially supported by Base Funding—UIDB/00511/2020 of the Laboratory for Process Engineering, Environment, Biotechnology and Energy—LEPABE—funded by national funds through the FCT/MCTES (PIDDAC); Project POCI-01-0145-FEDER-030431 (CLASInVivo) and project POCI-01-0145-FEDER-029841 (POLY-PREVENTT), funded by FEDER funds through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI) and by national funds (PIDDAC) through FCT/MCTES; Strategic funding of UIDB/04469/2020 of the Centre of Biological Engineering–CEB–funded by national funds through the FCT; Project BeMundus Brazil Europe/Erasmus Mundus scholarship granted by BM13DF0014

The use of biomimetic surfaces to reduce single- and dual-species biofilms of Escherichia coli and Pseudomonas putida

The ability of bacteria to adhere to and form biofilms on food contact surfaces poses serious challenges, as these may lead to the cross-contamination of food products. Biomimetic topographic surface modifications have been explored to enhance the antifouling performance of materials. In this study, the topography of two plant leaves, Brassica oleracea var. botrytis (cauliflower, CF) and Brassica oleracea capitate (white cabbage, WC), was replicated through wax moulding, and their antibiofilm potential was tested against single- and dual-species biofilms of Escherichia coli and Pseudomonas putida. Biomimetic surfaces exhibited higher roughness values (SaWC = 4.0 ± 1.0 μm and SaCF = 3.3 ± 1.0 μm) than the flat control (SaF = 0.6 ± 0.2 μm), whilst the CF surface demonstrated a lower interfacial free energy (ΔGiwi) than the WC surface (−100.08 mJ m−2 and −71.98 mJ m−2, respectively). The CF and WC surfaces had similar antibiofilm effects against single-species biofilms, achieving cell reductions of approximately 50% and 60% for E. coli and P. putida, respectively, compared to the control. Additionally, the biomimetic surfaces led to reductions of up to 60% in biovolume, 45% in thickness, and 60% in the surface coverage of single-species biofilms. For dual-species biofilms, only the E. coli strain growing on the WC surface exhibited a significant decrease in the cell count. However, confocal microscopy analysis revealed a 60% reduction in the total biovolume and surface coverage of mixed biofilms developed on both biomimetic surfaces. Furthermore, dual-species biofilms were mainly composed of P. putida, which reduced E. coli growth. Altogether, these results demonstrate that the surface properties of CF and WC biomimetic surfaces have the potential for reducing biofilm formation

Effect of surface conditioning with cellular extracts on Escherichia coli adhesion and initial biofilm formation

Bacterial adhesion and subsequent biofilm formation start with surface conditioning by molecules originating from the surrounding medium and from cell lysis. Different cell extracts e.g. total cell extract (TCE), cytoplasm with cellular debris (CCDE) and periplasmic extract (PE) were tested in agitated 96-well microtiter plates and in a flow cell. Crystal violet assay demonstrated that a polystyrene substratum conditioned with TCE or CCDE decreased initial biofilm formation, however cell adhesion generally increased when PE was used. These results were dependent on conditioning film concentration. Using a parallel plate flow chamber, the use of optimal conditioning film concentrations resulted in all the different cellular extracts reducing biofilm formation. Multifractal analysis was used to generate quantitative data on the number of cell clusters. Surface conditioning with cellular components affected the amount and clustering of bacteria on polystyrene surfaces and their propensity to induce biofilm formation. To the best of our knowledge, this is the first study addressing the effect of cellular surface conditioning of cellular compartments on E. coli adhesion and initial biofilm formation. This work leads to a greater understanding of the factors that influence biofilm formation under flow conditions which are prevalent in food industry

Celebrating the centenary in polymer science: Drawing inspiration from nature to develop anti-fouling coatings: the development of biomimetic polymer surfaces and their effect on bacterial fouling

The development of self-cleaning biomimetic surfaces has the potential to be of great benefit to human health, in addition to reducing the economic burden on industries worldwide. Consequently, this study developed a biomimetic wax surface using a moulding technique which emulated the topography of the self-cleaning Gladiolus hybridus (Gladioli) leaf. A comparison of topographies was performed for unmodified wax surfaces (control), biomimetic wax surfaces, and Gladioli leaves using optical profilometry and scanning electron microscopy. The results demonstrated that the biomimetic wax surface and Gladioli leaf had extremely similar surface roughness parameters, but the water contact angle of the Gladioli leaf was significantly higher than the replicated biomimetic surface. The self-cleaning properties of the biomimetic and control surfaces were compared by measuring their propensity to repel Escherichia coli and Listeria monocytogenes attachment, adhesion, and retention in mono- and co-culture conditions. When the bacterial assays were carried out in monoculture, the biomimetic surfaces retained fewer bacteria than the control surfaces. However, when using co-cultures of the bacterial species, only following the retention assays were the bacterial numbers reduced on the biomimetic surfaces. The results demonstrate that such surfaces may be effective in reducing biofouling if used in the appropriate medical, marine, and industrial scenarios. This study provides valuable insight into the antifouling physical and chemical control mechanisms found in plants, which are particularly appealing for engineering purposes

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Choosing when to clean and how to clean biofilms in heat exchangers

This is the author accepted manuscript of the article. The article is currently unpublished.Biofouling in heat exchangers can managed by regular cleaning. A mathematical framework for the optimisation problem involved in selecting the best cleaning schedules for such units is presented which considers (i) an induction period associated with conditioning and colonisation, which introduces complexity to the fouling kinetics, and (ii) the existence of several outcomes from cleaning, depending on the choice of cleaning method. The problem is to decide how, when and which exchanger to clean. A mixed integer non-linear programming approach, based on the use of a logistic function to model fouling resistance-time dynamics, is shown to give tractable results. The methodology is illustrated with a case study involving a small network of three heat exchangers. An optimized solution based on a cost/performance analysis shows that the cleaning intervals and cleaning methods differ between each exchanger.Financial support for Thomas Pogiatzis from the Onassis Foundation and the Cambridge European Trust is gratefully acknowledge