Biocidal Effect Research Articles

Design and Development of Fluorinated and Biocide-Free Sol-Gel Based Hybrid Functional Coatings for Anti-Biofouling/Foul-Release Activity.

Biofouling has destructive effects on shipping and leisure vessels, thus producing severe problems for marine and naval sectors due to corrosion with consequent elevated fuel consumption and higher maintenance costs. The development of anti-fouling or fouling release coatings creates deterrent surfaces that prevent the initial settlement of microorganisms. In this regard, new silica-based materials were prepared using two alkoxysilane cross-linkers containing epoxy and amine groups (i.e., 3-Glycidyloxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane, respectively), in combination with two functional fluoro-silane (i.e., 3,3,3-trifluoropropyl-trimethoxysilane and glycidyl-2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluorononylether) featuring well-known hydro repellent and anti-corrosion properties. As a matter of fact, the co-condensation of alkoxysilane featuring epoxide and amine ends, also mixed with two opportune long chain and short chain perfluorosilane precursors, allows getting stable amphiphilic, non-toxic, fouling release coatings. The sol–gel mixtures on coated glass slides were fully characterized by FT-IR spectroscopy, while the morphology was studied by scanning electron microscopy (SEM), and atomic force microscopy (AFM). The fouling release properties were evaluated through tests on treated glass slides in different microbial suspensions in seawater-based mediums and in seawater natural microcosms. The developed fluorinated coatings show suitable antimicrobial activities and low adhesive properties; no biocidal effects were observed for the microorganisms (bacteria).

Analysis of the Microbiome on the Surface of Corroded Titanium Dental Implants in Patients with Periimplantitis and Diode Laser Irradiation as an Aid in the Implant Prosthetic Treatment: An Ex Vivo Study.

The paper presents the optimization of diode laser irradiation of corroded dental implants in order to reduce the number of microorganisms associated peri-implantitis. The research included the identification of microorganisms on the surface of removed dental implants in patients with peri-implantitis and the assessment of the biocidal effectiveness of the diode laser against these microorganisms. Laser desorption/mass spectrometry (MALDI-TOF MS) was used to identify microorganisms and metagens were examined by next generation sequencing (NGS). Irradiation was performed with a diode laser with a wavelength of λ = 810, operating mode: 25 W/15.000 Hz/10 μs, average = 3.84 W with the number of repetitions t = 2 × 15 s and t = 3 × 15 s. The structure and surface roughness of the implants were analysed before and after laser irradiation by optical profilometry and optical microscopy with confocal fixation. In total, 16 species of Gram-positive bacteria and 23 species of Gram-negative bacteria were identified on the surface of the implants. A total of 25 species of anaerobic bacteria and 12 species with corrosive potential were detected. After diode laser irradiation, the reduction in bacteria on the implants ranged from 88.85% to 100%, and the reduction in fungi from 87.75% to 96.77%. The reduction in microorganisms in the abutment was greater than in the endosseous fixture. The applied laser doses did not damage, but only cleaned the surface of the titanium implants. After 8 years of embedding, the removed titanium implant showed greater roughness than the 25-year-old implant, which was not exposed to direct influence of the oral cavity environment. The use of a diode laser in an optimised irradiation dose safely reduces the number of microorganisms identified on corroded dental implants in patients with peri-implantitis.

Distinct responses of Pseudomonas aeruginosa PAO1 exposed to different levels of polystyrene nanoplastics

Large amounts of discarded plastics in the environment can be aged into microplastics and nanoplastics, which are not easily removed, posing potential nonnegligible risks to the ecosystem and human health. Although previous studies have revealed that nanoplastics have detrimental impacts on microorganisms, the potential molecular mechanisms of nanoplastic particles' effect on microbial growth and metabolism are still lacking. Here, multiple responses of Pseudomonas aeruginosa PAO1 (PAO1) to different levels of polystyrene nanoplastics (PS NPs) exposure were investigated by physiological experiments, live/dead staining, redox status, and genome-wide RNA sequencing. The results showed that PS NPs had dual effects on PAO1, and different concentrations of PS NPs demonstrated different effects on the growth and metabolism of PAO1. All levels of PS NPs had no obvious biocidal effect on PAO1. The production and consumption of ROS were in dynamic equilibrium and could be regulated genetically to ensure that the ROS level was in the biotolerable range. 20 and 50 mg/L of PS NPs severely inhibited the nitrate reduction, while 0.1 mg/L of PS NPs promoted the denitrification and TCA cycle. Meanwhile, 20 and 50 mg/L of PS NPs resulted in intense down-regulation of genes involved in denitrification. In contrast, the expression of genes involved in respiration is promoted with generated energy to withstand stress from high-level PS NPs, coinciding with the physiological results. In addition, our results showed that PS NPs concentrations of 20 and 50 mg/L exposure substantially up-regulated the expression of genes encoding for flagellar biosynthesis and biofilm formation to tackle the stress. Our findings would provide new insights into the interactions between environmental bacteria and PS NPs at the transcriptional level, thereby enhancing our understanding of the potential risks of PS NPs to microbial ecosystems and public health.

Prevalence of the fimbrial operon mrkABCD, mrkA expression, biofilm formation and effect of biocides on biofilm formation in carbapenemase-producing Klebsiella pneumoniae isolates belonging or not belonging to high-risk clones

The role of mrkA adhesin expression, biofilm production, biofilm viability and biocides in the biofilm of carbapenemase-producing Klebsiella pneumoniae isolates was investigated. Seventeen isolates representing different sequence types and carbapenemases were investigated. mrkA expression was determined by real-time reverse transcription polymerase chain reaction. Biofilm production (25°C and 37°C, with and without humidity) was determined by the crystal violet assay. The effect of isopropanol, povidone-iodine, sodium hypochlorite, chlorhexidine digluconate, benzalkonium chloride, ethanol and triclosan on biofilm was determined. The effect of povidone-iodine on biofilm biomass and thickness was also determined by confocal laser scanning microscopy. mrkA expression ranged from 28.2 to 1.3 [high or intermediate level; 64% of high-risk (HR) clones] and from 21.5 to 1.3 (50% of non-HR clones). At 25°C, biofilm formation was observed in 41% of isolates (absence of humidity) and 35% of isolates (presence of humidity), whereas at 37°C, biofilm formation was observed in 76% of isolates with and without humidity. At 25°C, biofilm producers were more frequently observed in HR clones (45% with humidity and 55% without humidity) than non-HR clones (17% with and without humidity). Biofilm viability from day 21 was higher at 25°C than 37°C. The greatest decrease in biofilm formation was observed with povidone-iodine (29% decrease), which also decreased biofilm thickness. Biofilm formation in carbapenemase-producing K. pneumoniae is related to mrkA expression. Biofilm formation is affected by temperature (37°C>25°C), whereas humidity has little effect. Biofilm viability is affected by temperature (25°C>37°C). At 25°C, HR clones are more frequently biofilm producers than non-HR clones. Povidone-iodine can decrease biofilm production and biofilm thickness.

Preparation of CO2 -Based Cationic Polycarbonate/Polyacrylonitrile Nanofibers with an Optimal Fibrous Microstructure for Antibacterial Applications.

Utilizing CO2 as one of the monomer resources, poly(vinylcyclohexene carbonates) (PVCHCs) are used as the precursor for preparing cationic PVCHCs (CPVCHCs) via thiol-ene click functionalization. Through the functionalization, CPVCHC-43 with a tertiary amine density of 43% relative to the backbone is able to display a significantly antibacterial ability against Staphylococcus aureus (S. aureus). Blending CPVCHC-43 with polyacrylonitrile (PAN), CPVCHC/PAN nanofiber meshes (NFMs) have been successfully prepared by electrospinning. More importantly, two crucial fibrous structural factors including CPVCHC/PAN weight ratio and fiber diameter have been systematically investigated for the effects on the antibacterial performance of the NFMs. Sequentially, a quaternization treatment has been employed on the NFMs with an optimal fibrous structure to enhance the antibacterial ability. The resulting quaternized NFMs have demonstrated the great biocidal effects against Gram-positive and Gram-negative bacteria. Moreover, the excellent biocompatibility of the quaternized NFMs have also been thoroughly evaluated and verified.

Insight on bacteria communities in outdoor bronze and marble artefacts in a changing environment

Epilithic bacteria play a fundamental role in the conservation of cultural heritage (CH) materials. On stones, bacterial communities cause both degradation and bioprotection actions. Bronze biocorrosion in non-burial conditions is rarely studied. Only few studies have examined the relationship between bacteria communities and the chemical composition of patinas (surface degradation layers). A better comprehension of bacterial communities growing on our CH is fundamental not only to understand the related decay mechanisms but also to foresee possible shifts in their composition due to climate change. The present study aims at (1) characterizing bacterial communities on bronze and marble statues; (2) evaluating the differences in bacterial communities' composition and abundance occurring between different patina types on different statues; and (3) providing indications about a representative bacterial community which can be used in laboratory tests to better understand their influence on artefact decay. Chemical and biological characterization of different patinas were carried out by sampling bronze and marble statues in Bologna and Ravenna (Italy), using EDS/Raman spectroscopy and MinION-based 16SrRNA sequencing.Significant statistical differences were found in bacterial composition between marble and bronze statues, and among marble patinas in different statues and in the same statue. Marble surfaces showed high microbial diversity and were characterized mainly by Cyanobacteria, Proteobacteria and Deinococcus-Thermus. Bronze patinas showed low taxa diversity and were dominated by copper-resistant Proteobacteria. The copper biocidal effect is evident in greenish marble areas affected by the leaching of copper salts, where the bacterial community is absent. Here, Ca and Cu oxalates are present because of the biological reaction of living organisms to Cu ions, leading to metabolic product secretions, such as oxalic acid. Therefore, a better knowledge on the interaction between bacteria communities and patinas has been achieved.

A Promising Antifungal and Antiamoebic Effect of Silver Nanorings, a Novel Type of AgNP.

Silver nanoparticles (AgNPs) play an important role in the medical field due to their potent antimicrobial activity. This, together with the constant emergence of resistance to antimicrobial drugs, means AgNPs are often investigated as an alternative to solve this problem. In this article, we analyzed the antifungal and antiamoebic effects of a recently described type of AgNP, silver nanorings (AgNRs), and compared them with other types of AgNPs. Tests of the activity of AgNPs against various fungal and amoebic species were carried out. In all cases, AgNPs showed a high biocidal effect, although with fungi this depended on the species involved. Antifungal activity was detected by the conditioning of culture media or water but this effect was not dependent on the release of Ag ions. On the other hand, the proliferation of Acanthamoeba castellanii trophozoites was reduced by silver nanorings (AgNRs) and silver nanowires (AgNWs), with AgNWs being capable of totally inhibiting the germination of A. castellanii cysts. AgNRs constitute a new type of AgNP with an antifungal and antiacanthamoebic activity. These results open the door to new and effective antimicrobial therapies as an alternative to the use of antifungals or antiamoebic drugs, thus avoiding the constant appearance of resistance and the difficulty of eradicating infections.

Pseudomonas fluorescens Cells' Recovery after Exposure to BAC and DBNPA Biocides.

A proper assessment of the effects of biocides on bacterial cells is key to the prevention of antimicrobial resistance and the implementation of suitable biocidal programmes. It is particularly relevant regarding the ability of dead-labelled cells to recover their functional processes once the biocide is removed. In the present work, we studied how Pseudomonas fluorescens cells previously exposed to different concentrations of BAC (benzalkonium chloride) and DBNPA (2,2-Dibromo-3-nitrilopropionamide) behave upon the restoration of optimum growth conditions. The following indicators were evaluated: culturability, membrane integrity, metabolic activity (resazurin), cellular energy (ATP), and cell structure and morphology (transmission electron microscopy (TEM)). The results demonstrated that cells previously labelled as ‘dead’ recovered to a greater extent in all indicators. Only cells previously exposed to BAC at 160 mg/L (concentration above the MBC) showed significant reductions on all the evaluated indicators. However, the obtained values were much higher than the ‘death’ thresholds found for the autoclaved cells. This suggests that cells exposed to this concentration take more time to rebuild their functional processes. The recovery of DBNPA-treated cells did not seem to be related to the biocide concentration. Finally, a reflection on what kind of cells were able to recover (remaining cells below the detection limit and/or dormant cells) is also presented.

An Engineered Nanocomposite Copper Coating with Enhanced Antibacterial Efficacy

AbstractContaminated surfaces are a major source of nosocomial infection. To reduce microbial bioburden and surface‐based transmission of infectious disease, the use of antibacterial and self‐sanitizing surfaces, such as copper (Cu), is being explored in clinical settings. Cu has long been known to have antimicrobial activity. However, Gram‐positive microorganisms, a class that includes pathogens commonly responsible for hospital‐acquired infection such as Staphylococcus aureus and Clostridioides difficile, are more resilient to its biocidal effect. Inspired by inherently bactericidal nanostructured surfaces found in nature, an improved Cu coating is developed, engineered to contain nanoscale surface features and thus increase its antibacterial activity against a broader range of organisms. In addition, a new method is established for facilitating the rapid and continuous release of biocidal metal ions from the coating, through incorporation of an antibacterial metal salt (ZnCl2) with a lower reduction potential than Cu. Electrophoretic deposition (EPD) is used to fabricate these coatings, which serves as a low‐cost and scalable route for modifying existing conductive surfaces with complex shape. By tuning both the surface morphology and chemistry, a nanocomposite Cu coating is created that decreases the microbial bioburden of Gram‐positive S. aureus by 94% compared to unmodified Cu.

Impact of magnesium addition in zinc oxide matrix for enhanced structural, optical, antimicrobial and anticancer properties

In the present work, low cost, high efficiency and multifunctional inorganic biocidal (antibacterial and anticancer) materials such as ZnO, MgO and MgZnO nanocomposites (NCs) have been developed with a facile precipitation process. XRD studies confirmed that the prepared NCs exhibit hexagonal, face-centered cubic and hexagonal structures respectively. Transmission electron microscopy (TEM) images revealed spherical shaped ZnO, MgO and MgZnO NCs. The elemental (Zn, Mg and O) compositions of the prepared NMs were identified using EDAX spectra. The photoluminescence (PL) spectra of the prepared NMs revealed oxygen vacancies at 487 nm, 500 nm and 524 nm respectively. They correspond to the active free radicals (OH, O2 and H2O2) production and these results were responsible for their biocidal activities. Furthermore, the biocidal effects of the MgZnO NCs were studied on the human breast cancer cell line and microbes. The cell viability studies proved that MgZnO NCs possess higher anticancer properties than ZnO and MgO NMs. Overall results displayed that the MgZnO NCs exposed better biocidal effects than ZnO and MgO NMs which can be used for biomedical and industrial applications to improve human health conditions.

The Use of the Diode Laser against the Microbiome on Composites Closing the Screw Access Hall (Sah) in the Reconstruction of Dental Implants: Ex Vivo Studies.

Patients undergoing implant treatment are at risk of peri-implant bone loss, which is most often caused by the adverse effects of microorganisms, but there are few proven procedures for their reduction. The aim of the research was to identify the microorganisms inhabiting the composites used to close the screw access hole (SAH), compare them numerically with those present on the surface of crowns and teeth, and optimize the doses of the diode laser, which will reduce microorganisms and will not deteriorate the roughness of polished composites. Patients were swabbed from the surface of SAH composites, from porcelain and zirconium restorations, and from teeth, and then the number of microorganisms was determined by using a culture technique. Microorganisms were identified by MALDI–TOF MS and NGS sequencing. The effectiveness of diode laser irradiation was achieved by using four variants of exposure. After polishing and laser irradiation, the surface roughness of the composites was studied by using optical profilometry. On the surface of SAH, 106 to 108 microorganisms were identified at 0.4 cm2, including many pathogenic species. Among the materials used for the reconstruction of dental implants, the greatest microbiological contamination was found on the composites used to close the SAH. The diode laser with a wavelength of 810 nm with an average power of 3.84 W, during 60 s and 2 × 30 s, has a biocidal effect and does not significantly change the surface roughness of composites. The best reduction of microorganisms was achieved on a composite polished with a polishing rubber and then with a Sof-Lex™ Pre-Polishing Spiral beige (3M ESPE, Ave. St. Paul., MN, USA). Studies have shown that using the optimal laser dose can help treat periimplantitis. These studies provide important information on the possibility of the effective elimination of microorganisms by using a diode laser in the treatment of peri-implant bone loss.

Essential Oils and Their Formulations for the Control of Curculionidae Pests

Pesticides are widely used in producing food to control pests. However, it has been determined that synthetic pesticides present severe toxicity (residual), while they also result in environmental contamination and development of high-level resistance in some insect species. Due to this, some of these susbtances have been banned or restricted in many countries, which has reduced the number of agrochemicals that can be used for pest control, particularly in the case of crops exported to green markets such as Europe and Asia. Under this scenario, essential oils (EOs) are being increasingly studied as bioinsecticides because they are renewable, natural, biodegradable, non-persistent in the environment and safe to non-target organism and humans. It has been determined that EOs have repellent, ovicidal, larvicidal, and insecticidal effects against different types of pests, but they also have some drawbacks due to their high volatility and low aqueous solubility. This mini-review focusses on EOs used as bioinsecticides for the control of Curculionidae and on current stabilization techniques, such as nanoencapsulation, to prolog the biocidal effect of EOs against these pests.

Biocide vs. Eco-Friendly Antifoulants: Role of the Antioxidative Defence and Settlement in Mytilus galloprovincialis

Antifoulant paints were developed to prevent and reduce biofouling on surfaces immersed in seawater. The widespread use of these substances over the years has led to a significant increase of their presence in the marine environment. These compounds were identified as environmental and human threats. As a result of an international ban, research in the last decade has focused on developing a new generation of benign antifoulant paints. This review outlines the detrimental effects associated with biocide versus eco-friendly antifoulants, highlighting what are effective antifoulants and why there is a need to monitor them. We examine the effects of biocide and eco-friendly antifoulants on the antioxidative defence mechanism and settlement in a higher sessile organism, specifically the Mediterranean mussel, Mytilus galloprovincialis. These antifoulants can indirectly assess the potential of these two parameters in order to outline implementation of sustainable antifoulants.

Microbial Protocols for Spacecraft: 1. Effects of Surface Texture, Low Pressure, and UV Irradiation on Recovery of Microorganisms from Surfaces.

Modeling risks for the forward contamination of planetary surfaces from endemic bioburdens on landed spacecraft requires precise data on the biocidal effects of space factors on microbial survival. Numerous studies have been published over the preceding 60 years on the survival of diverse microorganisms exposed to solar heating, solar ultraviolet (UV) irradiation, vacuum, ionizing radiation, desiccation, and many other planetary surface conditions. These data were generated with diverse protocols that can impair the interpretations of the results due to dynamic experimental errors inherent in all lab protocols. The current study (1) presents data on how metal surfaces can affect spore adhesion, (2) proposes doping and extraction protocols that can achieve very high recovery rates (close to 100%) from aluminum coupons with four Bacillus spp., (3) establishes a timeline in which dried spores on aluminum coupons should be used to minimize aging effects of spore monolayers, (4) confirms that vacuum alone does not dislodge spores dried on aluminum coupons, and (5) establishes that multiple UV irradiation sources yield similar results if properly cross-calibrated. The protocols are given to advance discussions in the planetary protection community on how to standardize lab protocols to align results from diverse labs into a coherent interpretation of how space conditions will degrade microbial survival over time.

Effects of atrazine and diuron on life parameters, antioxidant response, and multixenobiotic resistance in non-targeted marine zooplankton

Atrazine and diuron are among the most widely used antifoulant biocides in the world. Due to their persistence in the environment, they can induce adverse effects on non-targeted organisms. In this study, we investigated the chronic in vivo toxicity of atrazine and diuron with further assessments on oxidative stress responses (e.g., oxidative stress, antioxidant) and multixenobiotic resistance (MXR) function in the rotifer Brachionus koreanus, a non-targeted microzooplanktonic grazer at the primary level of the marine food chain. Although similar oxidative response was shown by both biocides, diuron induced stronger retardation on reproduction and population growth rates of B. koreanus while moderate effects were observed by atrazine. This higher toxicity of diuron was shown to be associated with its stronger inhibition of MXR conferred by P-glycoprotein and multidrug resistance proteins which play as a first line of defense by transporting various toxicants out of a cell. Our study provides new insight into non-targeted effects of biocides on marine zooplankton and mechanisms beyond their different degrees of toxicity.

Plant essential oils suspended into hydrogel: Development of an easy-to-use protocol for the restoration of stone cultural heritage

The development of phototrophic biofilms deteriorating stone cultural heritage is a well-known phenomenon that causes not only discoloration but also micro-decohesion of substrates. Recently, essential oils (EOs) have resulted as successful natural biocides to be used for the restoration of cultural heritage as an alternative to chemicals. In a first experiment EOs of Lavandula angustifolia Mill. and Thymus vulgaris L. at 5% concentration were tested against cyanobacterial biofilms. Moreover, to develop a suitable protocol for in situ application, diverse concentrations (0.5% - 0.25% - 0.1%) of T. vulgaris EO were encapsulated within an alginate hydrogel and applied for different times on cyanobacterial biofilms. Chemical profiles of the two EOs were investigated via GC-MS, to identify the main plant compounds underlying the biocidal effects. Results showed that T. vulgaris EO, rich in thymol, had the greatest inhibitory effect of photosynthetic efficiency compared to essential oil of L. angustifolia, especially if suspended into hydrogel. The development of such innovative protocol allowed the concentration of the tested essential oil to be 0.1% (v/v), maintaining antimicrobial efficacy against cyanobacteria and reducing the volatility of the terpene components. This innovative method will facilitate the application also on vertical surfaces and the removal of the biofilm.

Impact of <i>Candida spp.</i> metabolites on human skin fibroblasts

Micromycetes spp. have been increasingly involved in the etiology of infectious diseases guiding to consider them not as important as bacterial and viral pathogens. Nowadays, a lot of severe forms of candidiasis are caused by C. auris, C. albicans, whereas C. glabrata and C. krusei are of similar importance. Members of these species were selected to investigate related metabolite action on human skin fibroblasts. Candida spp. being continuously found on the epithelium and mucosal membranes resulting in to sustained interaction between microbiota and human cells. Potential to produce metabolites containing pathogenicity factors is one of the crucial events for transition to invasive candidiasis, wherein human epithelial cells build up the front line of defense barrier preventing Candida spp. invasion into deeper host tissues. The study was aimed at assessing data on metabolite effects derived from epidemiologically relevant Candida spp. on primary human skin fibroblast culture in vitro. In particular, there were analyzed Candida spp. metabolites acting on fibroblast monolayer integrity and viability in cell suspension. It was found that Candida spp. metabolites might directly cause fibroblast death so that biocidal activity was exhibited as a strain-specific feature. A direct biocidity against dermal cells was more typical for strains C. glabrata и C. krusei, less pronounced for C. albicans and very weak for C. auris. In addition, a mechanism for secretory product-related biocidal activity derived from various Candida spp. on dermal fibroblasts in vitro revealed that it resulted in fibroblasts death 1 hour after exposure that peaked at 3 hrs. Cell death was equally proceeded via apoptosis and necrosis. Of note, biocidal effect of fungal metabolites showed no correlation with Candida-related potential to cleave intercellular junctions. It was found that C. auris metabolites showing weak biocidity against some fibroblasts simultaneously resulted in more marked disruption of cell monolayer compared to other Candida spp. Perhaps, it is just a feature of C. auris that might account for its higher invasiveness potential allowing to destroy tight human tissues more effectively compared to other Candida spp.

Short Communication: Efficacy of Two Commercial Disinfectants on Paenibacillus larvae Spores.

Paenibacillus larvae is a spore-forming bacterium causing American foulbrood (AFB) in honey bee larvae. The remains of a diseased larva contains billions of extremely resilient P. larvae spores viable for decades. Burning clinically symptomatic colonies is widely considered the only workable strategy to prevent further spread of the disease, and the management practices used for decontamination requires high concentrations of chemicals or special equipment. The aim of this study was to test and compare the biocidal effect of two commercially available disinfectants, “Disinfection for beekeeping” and Virkon S on P. larvae. The two products were applied to P. larvae spores in suspension as well as inoculated on two common beehive materials, wood and Styrofoam. “Disinfection for beekeeping” had a 100 % biocidal effect on P. larvae spores in suspension compared to 87.0–88.6% for Virkon S which, however, had a significantly better effect on P. larvae on Styrofoam. The two disinfectants had similar effect on infected wood material.

Highly Efficient Industrial Dye Degradation, Bactericidal Properties, and In Silico Molecular Docking Analysis of Ag/Cellulose-Doped CuO Nanostructures.

In this research, CuO nanostructures doped with Ag and cellulose nanocrystals (CNC) were synthesized using a facile coprecipitation technique. In this work, we doped Ag into fixed quantities of CNC and CuO to improve the photocatalytic, catalytic, and antibacterial activity. It was noted that catalytic activity increased upon doping, which was attributed to the formation of nanorods and a pH effect, while the reverse trend was observed in photocatalytic activity. The addition of Ag and CNC dopants into CuO improved the bactericidal efficacy for S. aureus and E. coli. In addition, to obtain insight into the possible mechanism behind their biocidal effects, molecular docking studies were conducted against specific enzyme targets: namely, dihydrofolate reductase from E. coli and DNA gyrase from S. aureus. This study suggested that codoped CuO could be highly efficient in the cleaning of polluted water and antibacterial applications.

Low Temperature Plasma Strategies for Xylella fastidiosa Inactivation

The quarantine bacterium Xylella fastidiosa was first detected in Salento (Apulia, Italy) in 2013 and caused severe symptoms in olives, leading to plant death. The disease, named Olive Quick Decline Syndrome (OQDS), is caused by the strain “De Donno” ST53 of the subspecies pauca of this bacterium (XfDD), which is spread by the insect Philaenus spumarius. The epidemic poses a serious threat to the agricultural economy and the landscape, as X. fastidiosa infects several plant species and there is yet no recognized solution. Research on OQDS is focused on finding strategies to control its spread or mitigate its symptoms. As a perspective solution, we investigated the efficacy of the low-temperature plasma and plasma-activated water to kill bacterial cells. Experiments were conducted in vitro to test the biocidal effect of the direct application of a Surface Dielectric Barrier Discharge (SDBD) plasma on bacteria cells and Plasma Activated Water (PAW). PAW activity was tested as a possible biocidal agent that can move freely in the xylem network paving the way to test the strategy on infected plants. The results showed a high decontamination rate even for cells of XfDD embedded in biofilms grown on solid media and complete inactivation in liquid culture medium.