The negative consequences of biofilms are widely reported. A defining feature of biofilms is the extracellular matrix, a complex mixture of biomacromolecules, termed EPS, which contributes to reduced ...antimicrobial susceptibility. EPS targeting is a promising, but underexploited, approach to biofilm control allowing disruption of the matrix and thereby increasing the susceptibility to antimicrobials. Nanoparticles (NPs) can play a very important role as ’carriers’ of EPS matrix disruptors, and several approaches have recently been proposed. In this review, we discuss the application of nanoparticles as antibiofilm technologies with a special emphasis on the role of the EPS matrix in the physicochemical regulation of the nanoparticle–biofilm interaction. We highlight the use of nanoparticles as a platform for a new generation of antibiofilm approaches.
Self-adhering bacterial communities embedded in a matrix of hydrated macromolecules, known as biofilms, are prevalent and widespread. The matrix offers protection to the bacteria, reducing the cell susceptibility to antimicrobials.Functional nanoparticles are a promising technology to control or eradicate biofilms, providing the ability to enhance antimicrobial transport to the cell vicinity or alternatively to carry matrix dispersion agents.Critical to the development of novel strategies to control biofilm infections is an in-depth knowledge of the biofilm matrix which is still poorly understood due to its spatial and chemical variability and complexityA fundamental understanding of NP–EPS interactions has the potential to improve our ability to design more effective antibiofilm strategies.
Concentrations of trace elements in drinking water affect its safety and acceptability for use. Potentially toxic element (PTE) contaminations are considered extremely hazardous because of toxicity, ...persistence, and bioaccumulative behaviour. Many areas in the Southern African Development Community are data poor and have poor accessibility. The results of our previous research identified the presence of fossil waters in southern Limpopo National Park. Groundwater and river water are the only sources of drinking water for the villages in the study area. The current study focuses on the understanding of trace element distribution and health perspectives of PTEs (Hg, U, Sr, B, and Mn) in the groundwater and surface water samples (rivers and lakes) collected within the buffer zone of the Limpopo National Park, Southern Mozambique. Two sampling campaigns (October 2016–March 2017) were carried out during the end of the wet season and the end of the dry season to analyse the differences. The results improved our knowledge of the occurrence of trace elements in drinking water in an area where water resources play a fundamental role—because of their scarcity—and where the climate is harsh. ICP-MS results provided information on concentration ranges, highlighting the exceedance of the permissible maximum limit of mercury imposed by the World Health Organization on several groundwater samples. In the buffer zone of Limpopo Park, the highest levels of risk seem to be associated with the presence of Hg and U in drinking water. The use of risk assessment markers such as non-cancer risk value (hazard quotient HQ) revealed the exceedance of HQ values for Hg and U. The HQ values are higher in the wet season than the dry season, and most of the exceedance has been found in groundwater. HQ values are higher in exposed children than exposed adults. The water of Lake Massingir seems to be safer than any other source, but people do not currently use it because of the distance between the lake and their villages. Proactive control and research on alternative solutions for the water needs of the population and on creation of water distribution are recommended. In the current study, drinking water was the only route of exposure that was evaluated. Therefore, it would be appropriate to investigate the concentrations of PTEs in crops, livestock, and any other potential pathways.
The ubiquitous nature of bacterial biofilms combined with the enhanced resistance towards antimicrobials has led to the development of an increasing number of strategies for biofilm eradication. Such ...strategies must take into account the existence of extracellular polymeric substances, which obstruct the diffusion of antibiofilm agents and assists in the maintenance of a well-defended microbial community. Within this context, nanoparticles have been studied for their drug delivery efficacy and easily customised surface. Nevertheless, there usually is a requirement for nanocarriers to be used in association with an antimicrobial agent; the intrinsically antimicrobial nanoparticles are most often made of metals or metal oxides, which is not ideal from ecological and biomedical perspectives. Based on this, the use of polymeric micelles as nanocarriers is appealing as they can be easily prepared using biodegradable organic materials.
In the present work, micelles comprised of poly(lactic-co-glycolic acid) and dextran are prepared and then functionalised with curcumin. The effect of the functionalisation in the micelle's physical properties was elucidated, and the antibacterial and antibiofilm activities were assessed for the prepared polymeric nanoparticles against Pseudomonas spp. cells and biofilms. It was found that the nanoparticles have good penetration into the biofilms, which resulted in enhanced antibacterial activity of the conjugated micelles when compared to free curcumin. Furthermore, the curcumin-functionalised micelles were efficient at disrupting mature biofilms and demonstrated antibacterial activity towards biofilm-embedded cells.
Curcumin-functionalised poly(lactic-co-glycolic acid)-dextran micelles are novel nanostructures with an intrinsic antibacterial activity tested against two Pseudomonas spp. strains that have the potential to be further exploited to deliver a secondary bioactive molecule within its core.
Autocrine self-signalling via secreted peptides and cognate receptors regulates cell development in eukaryotes and is conserved from protozoans to mammals
. In contrast, secreted peptides from higher ...fungi have been traditionally associated with paracrine non-self-signalling during sexual reproduction
. For example, cells of the model fungus Saccharomyces cerevisiae fall into two distinct mating types (MAT), which produce either a- or α-pheromone and the cognate receptors Ste2 or Ste3, respectively
. Inappropriate autocrine pheromone signalling (APS) during mating is prevented by downregulation of the self-pheromone receptor
and by a-type cell-specific cleavage of α-pheromone through the protease Bar1 (refs.
). While APS can be artificially induced by manipulation of the pheromone secrete-and-sense circuit
, its natural occurrence in ascomycete fungi has not been described. Here, we show that Fusarium oxysporum-a devastating plant pathogen that lacks a known sexual cycle
-co-expresses both pheromone-receptor pairs, resulting in autocrine regulation of developmental programmes other than mating. We found that unisexual populations of MAT1-1 cells (α-type idiomorphs
) secrete and sense both a- and α-pheromone, and that their perception requires the cognate receptors and conserved elements of the cell wall integrity mitogen-activated protein kinase cascade. We further show that F. oxysporum uses APS to regulate spore germination in a cell-density-dependent manner, whereby the α-Ste2 interaction leads to repression of conidial germination while the a-Ste3 interaction relieves repression. Our results reveal the existence of a regulatory function for peptide pheromones in the quorum-sensing-mediated control of fungal development.
Biofilms are microbial communities embedded in an extracellular polymeric matrix and display an enhanced tolerance to the action of antimicrobials. The emergence of novel functionalised nanoparticles ...is considered a promising avenue for the development of biofilm-specific antimicrobial technologies. However, there is a gap in the understanding of interactions between nanoparticles and the biofilm matrix. Particularly, questions are raised on how nanoparticle charge and surface groups play a role in aggregation when in contact with biofilm components. Herein we present the synthesis of four types of silica nanoparticles and undertake an analysis of their interactions with Pseudomonas fluorescens biofilm matrix. The effect of the biofilm matrix components on the charge and aggregation of the nanoparticles was assessed. Additionally, the study focused on the role of matrix proteins, with the in-depth characterisation of the protein corona of each nanoparticle by Liquid Chromatography with Tandem Mass Spectrometry experiments. The protein corona composition is dependent on the nanoparticle type; non-functionalised nanoparticles show less protein selectivity, whereas carboxylate-functionalised nanoparticles prefer proteins with a higher isoelectric point. These outcomes provide insights into the field of biofilm-nanoparticle interactions that can be valuable for the design of new nano-based targeting systems in future anti-biofilm applications.
Thirteen soil samples were collected in April 2009 in Malagrotta's landfill, near Rome, to evaluate the geochemical factors that control the distribution pattern of trace elements and to define their ...natural and/or anthropogenic sources. Although the As and Pb mean values are lower than the natural background values for the sampled soil and the mean values of the other trace metal contents were lower than the natural abundance in the lithosphere and in the soil values, the geoaccumulation index (Igeo) suggests that the Malagrotta area is polluted by some of the studied metals. Moreover, a statistical analysis suggests that Cu, Zn, Cd, Sb, Pb, Cr, Ni and As constitute anthropogenic components, whereas the remaining elements (Tl, Rb and V) appear to be associated with parent rocks. It is demonstrated that the background may change from an area within a region and between regions. It's important that regulators recognise that the background depends on location and scale.
•We analysed trace metals in soils sampled in landfill.•We used the metal EF, Igeo and the statistical analysis to characterised the soil.•The Malagrotta area is moderately polluted for some of the studied metals.•The results show that soil controls the elements enrichment.
Purpose
Grass pea is a legume species with recognized resistance to several diseases and thus important for the improvement of related major legume crops. It is infected by the soil-borne fungus
...Fusarium oxysporum
f. sp.
pisi
(
Fop
), known as causal agent of pea fusarium wilt. We aim to identify, among grass pea, new sources of resistance against
Fop
and characterize the detected resistance mechanisms.
Methods
A grass pea worldwide collection of accessions was characterized under controlled conditions for response to
Fop
race 2. Fungal colonization dynamics and potential resistance mechanisms were studied through confocal laser scanning microscopy (CLSM) using
Fop
race 2 expressing green fluorescent protein (GFP).
Results
A quantitative nature of resistance to
Fop
, ranging from highly to partially resistant and susceptible accessions was detected, with resistance being the most frequent phenotype. Diverse colonization patterns were observed, suggesting the existence of different resistance mechanisms. In the highly resistant accessions, absence of fungal colonization in the vascular tissue was detected, while fungal progression was arrested at the level of roots both in highly resistant and partially resistant accessions.
Conclusions
The resistant accessions identified here can be exploited in grass pea breeding for fusarium wilt resistance, and due to the phylogenetic relatedness to pea, potentially contribute to pea improvement.
Wound healing is a complicated process, and the effective management of wounds is a major challenge. Natural herbal remedies have now become fundamental for the management of skin disorders and the ...treatment of skin infections due to the side effects of modern medicine and lower price for herbal products. The aim of the present study is to summarize the most recent in vitro, in vivo, and clinical studies on major herbal preparations, their phytochemical constituents, and new formulations for wound management. Research reveals that several herbal medicaments have marked activity in the management of wounds and that this activity is ascribed to flavonoids, alkaloids, saponins, and phenolic compounds. These phytochemicals can act at different stages of the process by means of various mechanisms, including anti-inflammatory, antimicrobial, antioxidant, collagen synthesis stimulating, cell proliferation, and angiogenic effects. The application of natural compounds using nanotechnology systems may provide significant improvement in the efficacy of wound treatments. Increasing the clinical use of these therapies would require safety assessment in clinical trials.
Water resources management is one of the most important challenges worldwide because water represents a vital resource for sustaining life and the environment. With the aim of sustainable groundwater ...management, the identification of aquifer recharge areas is a useful tool for water resources protection. In a well-developed karst aquifer, environmental isotopes provide support for identifying aquifer recharge areas, residence time and interconnections between aquifer systems. This study deals with the use of environmental isotopes to identify the main recharge area of a karst aquifer in the Upper Valley of Aniene River (Central Italy). The analysis of 18O/16O and 2H/H values and their spatial distribution make it possible to trace back groundwater recharge areas based on average isotope elevations. The Inverse Hydrogeological Balance Method was used to validate spring recharge elevations obtained by the use of stable isotopes. Areas impacted by direct and rapid rainfall recharge into the study area were delineated, showing groundwater flowpaths from the boundaries to the core of the aquifer. The results of this study demonstrate the contribution that spatial and temporal isotope changes can provide to the identification of groundwater flowpaths in a karst basin, taking into account the hydrogeological setting.
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