Browsing by Author "Cappitelli, Francesca"

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Development of a laboratory model of a phototroph-heterotroph mixed-species biofilm at the stone/air interface
(2015-11) Villa, Federica; Pitts, Betsey; Lauchnor, Ellen G.; Cappitelli, Francesca; Stewart, Philip S.
Recent scientific investigations have shed light on the ecological importance and physiological complexity of subaerial biofilms (SABs) inhabiting lithic surfaces. In the field of sustainable cultural heritage (CH) preservation, mechanistic approaches aimed at investigation of the spatiotemporal patterns of interactions between the biofilm, the stone, and the atmosphere are of outstanding importance. However, these interactions have proven difficult to explore with field experiments due to the inaccessibility of samples, the complexity of the ecosystem under investigation and the temporal resolution of the experiments. To overcome these limitations, we aimed at developing a unifying methodology to reproduce a fast-growing, phototroph-heterotroph mixed species biofilm at the stone/air interface. Our experiments underscore the ability of the dual-species SAB model to capture functional traits characteristic of biofilms inhabiting lithic substrate such as: (i) microcolonies of aggregated bacteria; (ii) network like structure following surface topography; (iii) cooperation between phototrophs and heterotrophs and cross feeding processes; (iv) ability to change the chemical parameters that characterize the microhabitats; (v) survival under desiccation and (vi) biocide tolerance. With its advantages in control, replication, range of different experimental scenarios and matches with the real ecosystem, the developed model system is a powerful tool to advance our mechanistic understanding of the stone-biofilm-atmosphere interplay in different environments.
Efficacy of zosteric acid sodium salt on the yeast biofilm model Candida albicans
(2011-05) Villa, Federica; Stewart, Philip S.; Giussani, Barbara; Roncoroni, S.; Albanese, Domenico; Giordano, C.; Tunesi, M.; Cappitelli, Francesca
Candida albicans is the most notorious and the most widely studied yeast biofilm former. Design of experiments (DoE) showed that 10 mg/L zosteric acid sodium salt reduced C. albicans adhesion and the subsequent biofilm formation by at least 70%, on both hydrophilic and hydrophobic surfaces of 96-well plates. Indeed, biofilm imaging revealed the dramatic impact of zosteric acid sodium salt on biofilm thickness and morphology, due to the inability of the cells to form filamentous structures while remaining metabolically active. In the same way, 10 mg/L zosteric acid sodium salt inhibited C. albicans biofilm formation when added after the adhesion phase. Contrary to zosteric acid sodium salt, methyl zosterate did not affect yeast biofilm. In addition, zosteric acid sodium salt enhanced sensitivity to chlorhexidine, chlorine, hydrogen peroxide, and cis-2-decenoic acid, with a reduction of 0.5 to 8 log units. Preliminary in vitro studies using suitable primary cell based models revealed that zosteric acid sodium salt did not compromise the cellular activity, adhesion, proliferation or morphology of either the murine fibroblast line L929 or the human osteosarcoma line MG-63. Thus the use of zosteric acid sodium salt could provide a suitable, innovative, preventive, and integrative approach to preventing yeast biofilm formation.
Hindering biofilm formation with zosteric acid
(2010-07) Villa, Federica; Albanese, Domenico; Giussani, Barbara; Stewart, Philip S.; Daffonchio, Daniele; Cappitelli, Francesca
The antifoulant, zosteric acid, was synthesized using a non-patented process. Zosteric acid at 500 mg l-1 caused a reduction of bacterial (Escherichia coli, Bacillus cereus) and fungal (Aspergillus niger, Penicillium citrinum) coverage by 90% and 57%, respectively. Calculated models allowed its antifouling activity to be predicted at different concentrations. Zosteric acid counteracted the effects of some colonization-promoting factors. Bacterial and fungal wettability was not affected, but the agent increased bacterial motility by 40%. A capillary accumulation test showed that zosteric acid did not act as a chemoeffector for E. coli, but stimulated a chemotactic response. Along with enhanced swimming migration of E. coli in the presence of zosteric acid, staining showed an increased production of flagella. Reverse transcriptase-PCR revealed an increased transcriptional level of the fliC gene and isolation and quantification of flagellar proteins demonstrated a higher flagellin amount. Biofilm experiments confirmed that zosteric acid caused a significant decrease in biomass (-92%) and thickness (-54%).
Subaerial biofilms on outdoor stone monuments: changing the perspective towards an ecological framework
(2016-04) Villa, Federica; Stewart, Philip S.; Klapper, Isaac; Jacob, J. M.; Cappitelli, Francesca
Despite the appreciation of the role played by outdoor stone heritage in societal well-being and sustainable urban development, research efforts have not been completely successful in tackling the complex issues related to its conservation. One of the main problems is that we are continuously underestimating the role and behavior of microorganisms in the form of biofilm (subaerial biofilms, SABs) in the management of stone artifacts. To this end, we discuss the necessity of approaching the topic from an ecological perspective through an overview of the characteristics of SABs that mediate different ecological interactions. Furthermore, we explore the application of functional-traits ecology to unravel the mechanisms by which SABs might respond to a changing environment. Finally, we guide and prioritize further research in order to inform policymakers and to develop management strategies for protection prior toâ€”or followingâ€”active conservation treatment.
Zosteric acid and salicylic acid bound to a low density polyethylene surface successfully control bacterial biofilm formation
(2018-04) Catto, C.; James, Garth A.; Villa, Federica; Villa, S.; Cappitelli, Francesca
The active moieties of the anti-biofilm natural compounds zosteric (ZA) and salicylic (SA) acids have been covalently immobilized on a low density polyethylene (LDPE) surface. The grafting procedure provided new non-toxic eco-friendly materials (LDPE-CA and LDPE-SA) with anti-biofilm properties superior to the conventional biocide-based approaches and with features suitable for applications in challenging fields where the use of antimicrobial agents is limited. Microbiological investigation proved that LDPE-CA and LDPE-SA: (1) reduced Escherichia coli biofilm biomass by up to 61% with a mechanism that did not affect bacterial viability; (2) significantly affected biofilm morphology, decreasing biofilm thickness, roughness, substratum coverage, cell and matrix polysaccharide bio-volumes by >80% and increasing the surface to bio-volume ratio; (3) made the biofilm more susceptible to ampicillin and ethanol. Since no molecules were leached from the surface, they remained constantly effective and below the lethal level; therefore, the risk of inducing resistance was minimized.
α-Chymotrypsin Immobilized on a Low-Density Polyethylene Surface Successfully Weakens Escherichia coli Biofilm Formation
(2018-12) Catto, Cristina; Secundo, Francesco; James, Garth A.; Villa, Federica; Cappitelli, Francesca
The protease α-chymotrypsin (α-CT) was covalently immobilized on a low-density polyethylene (LDPE) surface, providing a new non-leaching material (LDPE-α-CT) able to preserve surfaces from biofilm growth over a long working timescale. The immobilized enzyme showed a transesterification activity of 1.24 nmol/h, confirming that the immobilization protocol did not negatively affect α-CT activity. Plate count viability assays, as well as confocal laser scanner microscopy (CLSM) analysis, showed that LDPE-α-CT significantly impacts Escherichia coli biofilm formation by (i) reducing the number of adhered cells (−70.7 ± 5.0%); (ii) significantly affecting biofilm thickness (−81.8 ± 16.7%), roughness (−13.8 ± 2.8%), substratum coverage (−63.1 ± 1.8%), and surface to bio-volume ratio (+7.1 ± 0.2-fold); and (iii) decreasing the matrix polysaccharide bio-volume (80.2 ± 23.2%). Additionally, CLSM images showed a destabilized biofilm with many cells dispersing from it. Notably, biofilm stained for live and dead cells confirmed that the reduction in the biomass was achieved by a mechanism that did not affect bacterial viability, reducing the chances for the evolution of resistant strains.