Biocidal Effect Research Articles

Temporal Assessment of Biofumigation Using Mustard and Oilseed Rape Tissues on Verticillium dahliae, Soil Microbiome and Yield of Eggplant

Verticillium dahliae is a soil-borne pathogen that is difficult to eliminate, causes a severe reduction in the yield and quality of eggplant, and could be controlled through environmentally friendly biofumigation. However, the mechanisms of its effects on the dynamic changes of soil microbes is not clear. In this study, we examined the efficacy of two Brassica vegetables, mustard (Brassica napiformis, BFN) and oilseed rape (Brassica napus, BFC), as biofumigants to control Verticillium dahliae and observed their effects on the soil microbial community compared with chemical fumigants (CF) and a control (CN) in a greenhouse where eggplant was continuously cultivated for 12 years. Illumina MiSeq sequencing was used to analyse the soil microbiome. Real-time PCR was used to assay in order to estimate the soil abundance of Verticillium dahlia, and the glucosinolate concentration in biofumigants was determined using HPLC. Results showed that the BFN treatment had a significant biocidal effect on V. dahliae in the soil, decreasing its abundance by 64.74% compared to the control (CN). No significant difference was observed between BFC and CN treatments. Yield in the BFN treatment improved due to a lower disease incidence rate and disease index. Biofumigation had significant effects on the community structure and abundance of bacteria and fungi. The bacterial diversity of the BFN treatment was significantly lower than those of the other treatments, and beneficial bacterial community relative abundance, such as Flavobacteria, Pseudomonas and Bacillus, increased after the soil was biofumigated for 15 days. However, the temporal difference in bacterial and fungi structure among the different treatments was reduced with the development of the eggplant growth stage. The Mortierella, Altemaria and Chaetomium genera were significantly abundant across all treatments. Soil enzyme activities were also improved. In summary, biofumigation using mustard was efficient in controlling eggplant Verticillium wilt due to changes in the soil bacterial composition at the early eggplant growth stage; the initial conditions in the soil bacterial community are a key determinant of what is going to happen after Brassica biofumigation, which could be considered a practical addition to integrated pest management for the reduction of soil-borne pathogens.

Biocompatibility and biocidal effects of modified polylactide composites.

Polylactide (PLA) materials treated with antimicrobial fillers represent a suitable alternative to the production of medical devices. Their advantage is that they can prevent the growth of microorganisms and the formation of microbial biofilms on the surface and around composites. The work is focused on the evaluation of biocompatibility and biocide effect of PLA composite films filled with vermiculite and graphene oxide modified with silver (Ag+ and Ag nanoparticles), hexadecylpyridinium (HDP) and hexadecyltrimethylammonium (HDTMA) cations and their degradation leachates monitored at 1-3-6-month intervals. The antimicrobial effect of the leachates was detected by microdilution methods on gram-negative (Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis), gram-positive (Staphylococcus aureus, Streptococcus salivarius) bacteria and yeast (Candida albicans). The biocidal effect of composites on biofilm formation on the surface of composites was monitored by Christensen method and autoaggregation and motility tests. The biocompatibility of the composite and the leachates was assessed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) cytotoxicity assay. The evaluation of the antimicrobial effect of the leachates demonstrated that leachates of PLA composite filled with graphene oxide and Ag+ showed a stronger antimicrobial effect than leachates of PLA composite filled with vermiculite and Ag+ and Ag nanoparticles. The leachates of PLA composites containing vermiculite with HDP and HDTMA cations had a higher antimicrobial effect on G+ bacteria and yeast than G- bacteria. Bacterial growth, biofilm formation, autoaggregation and motility of the tested bacteria were most inhibited by the composite with vermiculite and Ag+ and Ag nanoparticles. Even after a 6-month degradation of this composite, bacterial growth and biofilm formation continued to be strongly inhibited up to 42 and 91%, respectively. The cytotoxic effect was proved only in the leachate of the composite with vermiculite containing HDP after 6 months of its degradation. Tests evaluating the biocompatibility of materials have shown that the vermiculite is the most preferred carrier and can be used in the future to bind other compounds. The study confirmed that PLA composite filled with vermiculite and Ag+ and Ag nanoparticles was the most stable and effective composite with the best biocompatible and biocidal properties.

Chemical Composition and Evaluation of Insecticidal Activity of Seseli bocconei Essential Oils against Stored Products Pests.

In this study, the chemical composition of the essential oils (EOs) obtained from different aerial parts (flowers, leaves, and stems) of Seseli bocconei Guss., a wild species endemic of Sicily, was investigated. Furthermore, the EOs' biocidal effects towards two pests of stored products, Sitophilus oryzae and Callosobruchus maculates, were evaluated. This activity was evaluated in Petri dish bioassays to establish the survival rate of adults treated with the EOs comparing them with solvent and a commonly used insecticide (pyrethrum). The data obtained from the toxicity bioassay evidenced that stems' EOs and leaves' EOs have a contact/fumigation effect towards the two insect species tested, while the EOs from the flowers did not exhibit a different mortality than the solvent. The EOs from the stem and leaves of S. bocconei, tested at 10 mg/petri dish, determined a LT50 of 53.38 and 42.97 h, respectively, on S. oryzae adults, and of 45.23 and 42.97 h, respectively, on C. maculatus adults. The promising bioactivity of S. bocconei leaves' EOs and stems' EOs toward S. oryzae and C. maculatus is encouraging in the perspective to test these oils and their main constituents for further experiments in the laboratory and field.

Don’t be scared to touch! Effectiveness of a new disinfection technology based on Ag ions & Zeolite

Abstract Background Disinfection of contact surfaces has become common practice since the two-year Covid-19 pandemic. The transmission of microbial agents has long been the focus of public health and hygiene awareness campaigns. Indeed, the development of new disinfection technologies and approaches is attracting considerable interest in the scientific community. Mixed plastic powders with antimicrobial properties and silver ions that compromise the metabolism of microorganisms could reduce the contamination of the contact surfaces. We aimed to evaluate an inorganic antimicrobial agent (IAA) based on Ag ions and zeolite mixed in a resin. Methods This experimental study was carried out at the University of Siena, Italy. Different objects were produced in two versions: i) with an IAA mixed in plastic resin; ii) with a standard plastic mixture. To the eye, the two versions were indistinguishable and were randomly contaminated with the hands of several operators. After the hand contamination, T0, we sampled the objects using RODAC plates at T1 (1h) and T2 (6h), incubating at 36 °C for 48 hours. Comparisons of the biocidal effect were made at T1 and T2. Statistical analysis was carried out with Stata. Results The mean level of contamination of the objects made with standard plastic were, respectively 50 CFU (SD 36.5) at T1 and 20 CFU (SD 13.6) at T2. In comparison, the objects made with IAA resin showed a mean level of contamination of 10 CFU (SD 5.9) at T1 and 6 CFU (SD3.6) at T2. The objects made with IAA resin have shown a mean percentage reduction of contamination of 79.5% at T1 and 78.3% at T2. Conclusions IAA resin reduced contamination on objects that came into contact with hands. Antimicrobial plastic blends, are a valuable aid in counteracting the spread of infection related to contact with surfaces and fomites. The public health system could support and raise awareness for using these innovative materials for everyday applications and in healthcare facilities. Key messages • Inorganic antimicrobial agent based on Ag ions and Zeolite mixed in a resin are efficient in reducing the contamination on different items in a real-life context. • Public health system have to support and sensitize to production with inorganic materials with proven antimicrobial properties.

A novel technology for disinfecting surfaces infested with Candida auris: the UVC chip

Abstract Background The fungal pathogen Candida Auris is increasingly associated with multidrug-resistant infections that are highly expensive for the Health Care System. The spreading of this pathogen can occur, among others, through contact with infected surfaces or medical instruments. This study evaluated the efficacy of a novel UVC chip, novel alternative to UVC LEDs and lamps, in inactivating Candida auris strain. Methods This experimental study was carried out between July and September 2020 at the University of Siena. Candida auris (ATCC 12372) at two known concentrations (1.5X107 and 1.5x106 CFU/ml) at a fixed distance (7,5 cm) from the chip (5.1mW radiant power) was tested, in triplicates, with three exposure times (5, 10 and 15 minutes). Potato Dextrose Agar (PDA) plates without the plate lid and containing Candida auris were exposed to UVC light. Subsequently, the plates were incubated at 36 °C for 48 h. Log reduction between treated and positive control (not exposed to UVC light) samples was calculated. Results At 15 minutes, we had the highest inactivation result, mean 4.43 log10, starting from a 1.5x106 CFU/mL concentration. At a higher concentration, 1.5X107 CFU/mL, the reduction had a mean of 3.51 log10. Conclusions The results of the experiments showed a significant microbial reduction in relation to the exposure time. The highest level of reduction was reached after 15 minutes of exposure. UVC chip had a relevant biocidal effect on Candida auris and may represent a valuable tool in the prevention of infections caused by this pathogen, which is becoming increasingly prevalent and persistent globally. Key messages • The use of UVC Chip decreases surface contamination. • New technology against healthcare-associated infections.

Synthetic polyurethane nanofibrous membrane with sustained rechargeability for integrated air cleaning

Health problems caused by airborne particulate matter (PM) and bacteria have placed a severe burden on public health. At present, most personal protective equipment focused on PM filtration but ignored the threat from pathogens like bacteria in the air. Moreover, the disposable protective items such as masks used in large quantities have caused great pollution issues. Hence, in this study, a fresh polyurethane nanofibrous membrane (named as PU/PIU-Cl) was synthesized with imidazolidinyl urea groups as block components for enhanced biocidal effect which not only has extremely high filtration efficiency (up to 99.92%) against particulate pollutants, but also excellent intrinsic antibacterial ability (>99%) and safety, indicating its remarkable performance for integrated air pollution control. Furthermore, the antibacterial ability of the membrane can be facilely regenerated by re-chlorination, and the active chlorine content of PU/PIU-Cl membrane through halogenation hardly decreased after five cycles. Therefore, the PU/PIU-Cl nanofibrous membrane can not only be used as protective equipment, such as masks with sterilization function, but also can effectively alleviate the pollution problem of disposable protective products. • Imidazolidinyl urea groups are employed as block components of polyurethane. • PU/PIU-Cl exhibits intrinsic antibacterial function and high filtration efficiency. • PU/PIU-Cl is low cytotoxic, low cost and reusable, and shows great potential in PPE.

Anti-proliferative and biocidal effect of watermelon (Citrullus lanatus) seed extract and its nanoformulation

• A facile and green synthesis of nanoparticles of Watermelon seeds is proposed. • No chemical precursors or surfactants were used. • The nanoparticles exhibited profound antibacterial and antiproliferative activity. • It is a potential novel nutraceutical with a prospective role in cancer therapy. Watermelon ( Citrullus lanatus ) seeds are endowed with phytonutrients that ascribe to their potent antioxidant status. The present study proposes a facile and novel green synthesis of nanoparticles of the seed extract. The synthesized nanoparticles showed a mean average size of 215 nm with a single significant peak and a polydispersity index (PDI) of 0.11.The electron micrographs showed spherical nanoparticles dispersed without agglomeration The biocidal and the antiproliferative effect on cancer cell lines (HCT-116, HepG-2, HeLa) of the nanoparticles (WMnano) was more pronounced as compared to the bulk seed extract (WMS).

Rhamnolipids and fengycins, very promising amphiphilic antifungal compounds from bacteria secretomes, act on Sclerotiniaceae fungi through different mechanisms.

Rhamnolipids (RLs) and fengycins (FGs) are amphiphilic lipid compounds from bacteria secretomes proposed to replace synthetic pesticides for crop protection. They both display plant defense triggering properties and direct antimicrobial activities. In particular, they have well reported antifungal effects against phytopathogenic fungi. RLs and FGs are considered to act through a direct interaction with membrane lipids and a destabilization of microorganism plasma membrane, thereby limiting the risk of resistance emergence. The main objective of this work was to gain insights in the antimycelial mode of action of these metabolites to promote them as environment and human health friendly biocontrol solutions. Their biocidal effects were studied on two Sclerotiniaceae fungi responsible for diseases in numerous plant species worldwide. We show here that different strains of Botrytis cinerea and Sclerotinia sclerotiorum have opposite sensitivities to RLs and FGs on plate experiments. Overall, B. cinerea is more sensitive to FGs while S. sclerotiorum is more sensitive to RLs. Electron microscopy observations demonstrated that RLs induce mycelial destructuring by asperities emergence and hyphal fusions whereas FGs promote swelling and formation of vesicle-like structures due to vacuole fusions and autophagy. Permeability studies, phosphatidylserine externalization and reactive oxygen species production assessments showed a programmed cell death triggering by RLs at medium concentrations (until 50 μg mL−1) and necrosis characteristics at higher concentration. Programmed cell death was always observed on hyphae treated with FGs. Quantifications of mycelial ergosterol content indicated that a higher ergosterol rate in S. sclerotiorum correlates with increasing sensitivity to RLs. Oppositely, a lower ergosterol rate in B. cinerea correlates with increasing sensitivity to FGs, which was confirmed by ergosterol biosynthesis inhibition with tebuconazole. This gain of knowledge will help to better understand the mode of action of RLs and FGs to fight specific plant fungal diseases.

Microbial protocols for spacecraft: 2. Biocidal effects of Delrin and nylon in sealed compartments may enhance bioburden reductions in planetary spacecraft

AbstractInterplanetary spacecraft are assembled with thousands of parts composed of many diverse materials. Little is known on whether any of the spacecraft materials are biocidal to the typical microbiomes that develop on spacecraft during pre-launch processing. During ongoing experiments to examine the interactive effects of solar UV irradiation, solar heating, ionizing radiation, and vacuum, we observed that bacterial spores of three Bacillus spp. were killed when incubated within small vacuum chambers for 5 days – without exposure to the aforementioned factors. Eight potential spacecraft materials were tested within the vacuum chambers for biocidal activities against spores of B. atrophaeus ATCC 9372, B. pumilus SAFR-032 and B. subtilis 168. All three species were fully inactivated (i.e., no survivors detected) by machined parts manufactured from Delrin®; a thermoplastic polyacetal polymer. Although not tested here, it is known that Delrin can off-gas formaldehyde, and thus, we hypothesize that this volatile organic compound (VOC) was responsible for the biocidal activity of the material. Knowledge of the biocidal nature of routinely used spacecraft materials might offer diverse methods to inactivate deeply embedded or shielded microbiota within spacecraft via the release of biocidal VOCs.

Combining Topography and Chemistry to Produce Antibiofouling Surfaces: A Review.

Despite decades of research on the reduction of surface fouling from biomolecules or micro-organisms, the ultimate antibiofouling surface remains undiscovered. The recent covid-19 pandemic strengthened the crucial need for such treatments. Among the numerous approaches that are able to provide surfaces with antibiofouling properties, chemical, biological, and topographical strategies have been implemented for instance in the marine, medical, or food industries. However, many of these methods have a biocidal effect and, with antibioresistance and biocide resistance a growing threat on humanity, strategies based on reducing adsorption of biomolecules and micro-organism are necessary for long-term solutions. Bioinspired strategies, combining both surface chemistry and topography, are currently at the heart of the best innovative and sustainable solutions. The synergistic effect of micro/nanostructuration, together with engineered chemical or biological functionalization is believed to contribute to the development of antibiofouling surfaces. This review aims to present approaches combining hydrophobic or hydrophilic chemistries with a specific topography to avoid biofouling in various industrial environments and healthcare facilities.

Green Synthesis of Hexagonal Silver Nanoparticles Using a Novel Microalgae Coelastrella aeroterrestrica Strain BA_Chlo4 and Resulting Anticancer, Antibacterial, and Antioxidant Activities.

Microalgae-mediated synthesis of nanoparticles (NPs) is an emerging nanobiotechnology that utilizes the biomolecular corona of microalgae as reducing and capping agents for NP fabrication. This study screened a novel microalgal strain for its potential to synthesize silver (Ag)-NPs and then assayed the biological activities of the NPs. Coelastrella aeroterrestrica strain BA_Chlo4 was isolated, purified, and morphologically and molecularly identified. Chemical composition of the algal extract was determined by GC-MS analysis. Ag-NPs were biosynthesized by C. aeroterrestrica BA_Chlo4 (C@Ag-NPs) and characterized using various techniques. Antiproliferative activity and the biocidal effect of C@Ag-NPs, C. aeroterrestrica algal extract, and chemically synthesized Ag-NPs (Ch@Ag-NPs) were explored, and the scavenging activity of C@Ag-NPs against free radicals was investigated. C@Ag-NPs were hexagonal, with a nanosize diameter of 14.5 ± 0.5 nm and a maximum wavelength at 404.5 nm. FTIR and GC-MS analysis demonstrated that proteins and polysaccharide acted as capping and reducing agents for C@Ag-NPs. X-ray diffraction, energy diffraction X-ray, and mapping confirmed the crystallinity and natural structure of C@Ag-NPs. The hydrodynamic diameter and charge of C@Ag-NPs was 28.5 nm and −33 mV, respectively. C@Ag-NPs showed significant anticancer activity towards malignant cells, with low toxicity against non-cancerous cells. In addition, C@Ag-NPs exhibited greater antioxidant activity and inhibitory effects against Gram-positive and -negative bacteria compared with the other tested treatments. These findings demonstrate, for first time, the potential of a novel strain of C. aeroterrestrica to synthesize Ag-NPs and the potent antioxidant, anticancer, and biocidal activities of these NPs.

A novel phenolic derivative inhibits AHL-dependent quorum sensing signaling in Pseudomonas aeruginosa.

Increasing antibiotic resistance and the decline in the pharmaceutical industry’s investments have amplified the need for novel treatments for multidrug-resistant bacteria. Quorum sensing (QS) inhibitors reduce pathogens’ virulence without selective pressure on bacteria and provide an alternative to conventional antibiotic-based therapies. P. aeruginosa uses complex QS signaling to control virulence and biofilm formation. We aimed to identify inhibitors of P. aeruginosa QS acting on acyl-homoserine lactones (AHL)-mediated circuits. Bioluminescence and qRT-PCR assays were employed to screen a library of 81 small phenolic derivatives to reduce AHL-dependent signaling. We identified GM-50 as the most active compound inhibiting the expression of AHL-regulated genes but devoid of cytotoxic activity in human epithelial cells and biocidal effects on bacteria. GM-50 reduces virulence factors such as rhamnolipids, pyocyanin, elastase secretion, and swarming motility in P. aeruginosa PAO1 laboratory strain. By molecular docking, we provide evidence that GM-50 highly interacts with RhlR. GM-50 significantly improved aztreonam-mediated biofilm disruption. Moreover, GM-50 prevents adhesion of PAO1 and inflammatory damage in the human A549 cell line and protects Galleria mellonella from PAO1-mediated killing. GM-50 significantly reduces virulence factors in 20 P. aeruginosa clinical isolates from patients with respiratory tract infections. In conclusion, GM-50 inhibits AHL-signaling, reduces virulence factors, enhances the anti-biofilm activity of aztreonam, and protects G. mellonella larvae from damage induced by P. aeruginosa. Since GM-50 is active on clinical strains, it represents a starting point for identifying and developing new phenolic derivatives acting as QS-inhibitors in P. aeruginosa infections.

Inhibition of Borrelia Burgdorferi-Induced TLR2-NFκB Canonical Signaling by Gallic Acid through Targeting the CD14+ Adaptor Protein and p65 Molecule.

The cases of Lyme disease caused by Borrelia burgdorferi infection have been increasing throughout Northern America and Europe. This pathogen, if not treated in a timely manner with antibiotics, can cause persisting and debilitating health outcomes. In the search for novel agents against B. burgdorferi, we investigated a phenolic compound—gallic acid—for its anti-Borrelia and anti-inflammatory effects. Our results showed its biocidal effect starting from 100 μg/mL against active spirochetes, persisters/round-shaped bodies, and biofilm like aggregates of B. burgdorferi sensu stricto. Activation of macrophages by live B. burgdorferi also resulted in a robust NFκB-dependent proinflammatory responses seen in increased production of cytokines. Using human CD14+ macrophages in vitro, we showed that CD14+ adaptor and phosphorylated p65 molecule are impeded at nonbiocidal and noncytotoxic concentrations of gallic acid, resulting in the inhibition of both expression and secretion of cytokines IL1β, IL6, and TNFα. Our findings demonstrate efficacy of gallic acid against B. burgdorferi and provide potential mechanistic insight into its TLR2/CD14+-NFκB mediated mode of action. Further studies on the potential of gallic acid as a safe and effective compound against Borrelia-caused infection are warranted.

Antimicrobial activity of traditional and newly synthetized surface-active agents as a basis for the creation of new disinfectants

Aim. The main goal of the study was to investigate the antibacterial and fungicidal properties of the traditional and newly synthesized surfactants of different classes, compare the analysis of their antimicrobial activity and find out the prospects for further use for the creation of disinfectants. Methods. The biocidal activity of the studied cationic, anionic and nonionic surfactants was determined in relation to representatives of the species Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, as well as fungi Candida albicans. The detection of antibacterial and fungicidal effect and determination of minimum inhibitory concentrations (MIC) was carried out by cultivation of the test cultures of microorganisms in Nutrient Broth (NB, Himedia, India) for 24–48 hours at 37 °С in the presence of different concentrations of experimental surfactants (1000–0.1 ppm). The number of cells that remained viable after exposure to surfactants was determined by optical density in McFarland units, which were then converted to the number of cells in 1 ml using the standard McFarland scale. Results. The newly synthesized guanidine-containing oligomer at concentrations of 1000 and 100 ppm inhibited the growth of all test cultures without exception by 100 %. The biocidal effect on the representatives of various taxonomic groups of microorganisms differed in its effectiveness for various anionic surfactants (trilon B, surfactant 2 and surfactant 3) even at the highest concentration of 1000 ppm. In particular, only trilon B completely inhibited the growth of all test cultures. However, at the concentrations indicated above, the examined cationic (surfactant 1 and triethanolamine) and nonionic (OP-10 and triton X-100) exhibited a rather low antimicrobial activity. Conclusions. The results obtained indicate that the guanidine-containing oligomer exhibited the highest antimicrobial activity among the investigated surfactants. Therefore, it can be considered a promising surfactant for further use in the creation of broad-spectrum antimicrobial agents. Enhancement of the biocidal effect of newly created disinfectants can be implemented by introducing the studied anionic and nonionic detergents, and glutaraldehyde can be used to stabilize them or enhance their antimicrobial activity. Instead, the application of cationic surfactants used in the work is impractical.

Performance of Iron(II)-Sulphate-Treated Norway Spruce and Siberian Larch in Laboratory and Outdoor Tests

Wood in outdoor applications is exposed to various environmental factors that cause weathering. Weathering is important, primarily from an aesthetic standpoint and predominantly in wooden claddings. However, not all parts of claddings are equally exposed to weathering. Sections exposed to UV radiation and moisture discolour faster than less exposed sections, such as wood under roof overhangs. Architects and owners seek a uniform appearance in buildings. To achieve fast and uniform greying, a surface treatment with iron(II) sulphate can be used. Such a treatment results in an appearance that is similar to that resulting from natural greying. However, iron compounds do not exert a biocidal effect; therefore, it is desirable to upgrade iron(II) sulphate aqueous solution with boric acid and quarterly ammonium compounds. To this end, spruce and larch samples were treated with varying concentrations of iron(II) sulphate and biocides. After treatment, the inherent durability, water performance and resistance dose (DRd) were determined according to the Meyer-Veltrup model. The samples were also exposed outdoor conditions. During exposure, colour changes and iron leaching were monitored. The results show that the addition of biocides does not affect the rate of colour change and the final colour, which is similar to natural greying after 36 weeks of outdoor exposure. The addition of biocides exerted a positive effect on the durability of treated wood, despite the low retention of preservative solutions. The water behaviour of the treated wood had little effect on the resistance dose, with a more considerable influence on inherent durability. The addition of biocides can increase the resistance dose up to 2.4 (Fe5B0.2Q0.2). On all spruce and larch samples treated with iron(II) sulphate and exposed to outdoor conditions, the colour change in the first week was roughly comparable to the final state. However, 40% of the iron had leached from the surface after only one week of exposure.

Variability in Biological Activities of Satureja montana Subsp. montana and Subsp. variegata Based on Different Extraction Methods.

Winter savory (Satureja montana L.) is a well-known spice and medicinal plant with a wide range of activities and applications. Two subspecies of S. montana, subsp. montana and subsp. variegata, were used for the preparation of seven different extracts: steam distillation (essential oil (EO) and hydrolate (HY)), subcritical water (SWE), ultrasound-assisted (UAE-MeOH and UAE-H2O), and microwave-assisted (MAE-MeOH and MAE-H2O) extraction. The obtained EOs, HYs, and extracts were used for an in vitro evaluation of the antioxidant activity (DPPH, ABTS, reducing power, and superoxide anion methods) and in vitro antimicrobial activity against Bacillus cereus, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Salmonella Typhimurium, Saccharomyces cerevisiae, and Candida albicans. The antimicrobial screening was conducted using disk-diffusion assessment, minimal inhibitory concentration, time–kill kinetics modeling, and pharmacodynamic study of the biocide effect. The total phenolic content (TPC) was highest in EO, followed by SWE, MAE, and UAE, and the lowest was in HY. The highest antimicrobial activity shows EO and SWE for both varieties, while different UAE and MAE extracts have not exhibited antimicrobial activity. The natural antimicrobials in the S. montana extract samples obtained by green extraction methods, indicated the possibility of ecologically and economically better solutions for future in vivo application of the selected plant subspecies.

Combined Biocidal Effect of Gaseous Ozone and Citric Acid on Acinetobacter baumannii Biofilm Formed on Ceramic Tiles and Polystyrene as a Novel Approach for Infection Prevention and Control

Acinetobacter baumannii is a prominent emerging pathogen responsible for a variety of hospital-acquired infections. It can contaminate inanimate surfaces and survive in harsh environmental conditions for prolonged periods of time in the form of biofilm. Biofilm is difficult to remove with only one method of disinfection, so combined disinfection methods and biocidal active substances are needed for biofilm eradication. Additionally, having in mind ecological demands, legislators are more prone using fewer toxic substances for disinfection that produce less solid waste and hazardous disinfection byproducts. Gaseous ozone and citric acid are natural biocidal compounds, and the purpose of this study was to determine their combined biocidal effects on A. baumannii biofilm formed on ceramics and polystyrene. Twenty-four-hour A. baumannii biofilm formed on ceramic tiles and polystyrene was exposed to different combinations of disinfection protocols with 25 ppm of gaseous ozone for 1 h exposure time and 15% citric acid for 10 min exposure. The total number of bacteria was counted afterwards and expressed as CFU/cm2. The determined disinfection protocols of A. baumannii biofilm with combined citric acid and gaseous ozone caused reduction of 2.8 to 5.89 log10 CFU (99.99% inhibition rate) of total viable bacteria for each method, with the citric acid–ozone–citric acid disinfection protocol being most successful in eradication of viable bacteria on both ceramics and polystyrene. In conclusion, gaseous ozone and citric acid showed good combined biocidal effects on A. baumannii biofilm and successfully reduced early A. baumannii biofilm from ceramic and polystyrene surfaces. The given combination of active substances can be a good option for eco-friendly disinfection of hospital inanimate surfaces from A. baumannii biofilm contamination with prior mechanical cleaning.

Https://gsconlinepress.com/journals/gscbps/ArchiveIssue-2022-Vol20-Issue2

This laboratory study was conducted to evaluate the biocidal effect of Crataeva religiosa (Capparidaceae) on eggs and adults of Caryedon serratus. An aqueous formulation obtained by maceration at 50 degrees was used in three concentrations 0.2kg/L, 0.1kg/L, 0.06kg/L. The results reveal that the extracts of C. religiosa showed a rather remarkable ovicidal activity which varies from 41.66% in C1 and C2 to 38.88% in C3. A very important nymphal activity of 88.88% was also noted with the highest dose. The monitoring of surviving eggs showed a lengthening or a shortening of the different development durations and an imbalance of the sex ratio in favor of females. The adulticidal activity showed mortality spread over time of all doses. The extracts of C. religiosa showed a fairly high adulticidal activity of 53.33% in C1, 40% in C2 and 46.66% in C3. A reduction in the fecundity of females treated with all doses was also noted and a balance in the sex ratio of survivors from treated adults.

Biocidal effect of Crataeva religiosa extracts against Caryedon serratus (Olivier, 1789) pest of peanut stocks and seeds in Senegal

Biocidal effect of Crataeva religiosa extracts against Caryedon serratus (Olivier, 1789) pest of peanut stocks and seeds in Senegal

Sporicidal Action of Pulsed Radiation of Hot Plasma.

In the study, we used a Pilimin IR-10 spark discharge generator as a source of pulsed radiation of hot plasma; a corona discharge generator - as a source of cold plasma; a DKB-9 low-pressure mercury lamp - as a source of continuous radiation of UV band, wavelength of 253.7 nm. The samples were processed in Petri dishes, 40 mm in diameter, their volume being 4 and 10 cm3. The study used an L-tyrosine solution in distilled water (the concentration: 160 mg/L), a suspension of bacteria and spores of micromycetes (its concentration being ~106 cells per 1 ml). Tyrosine conversion products were identified spectrophotometrically before and after treatment. The biocidal and sporicidal effects were assessed by counting CFU (colony-forming units) after seeding incubation at 27-37°C. The oxidation of tyrosine by HO2• radicals was found to be impossible. Under 2 the action of nitrogen compounds, nitration proceeds with 3-nitrotyrosine formation. The nitration reaction is slow, taking about 100 h. A possible nitration mechanism is through the formation of the nitronium ion NO2+ in an acidic medium.The biocidal effect of hot plasma radiation turned out to be weaker than that of UV radiation of a DKB-9 lamp. This is due to the difference in their emission spectrum. The sporicidal effect of hot plasma radiation was more pronounced: a 10-fold decrease in the number of CFU was observed at radiation doses of 200-280 J. Under the action of UV radiation, at the same doses, the decrease in the number of CFU was from 3 to ~30%. The sporicidal effect of hot plasma radiation is due to the decay of a long-living …ONOOH/ONOO-… complex with the formation of a nitric oxide and a nitronium ion in an acidic medium. The study showed the viability of spores under the action of pulsed radiation of hot plasma to decrease. While the light radiation of a UV lamp, under studied conditions, slightly penetrates the protective coating of a spore. The sporicidal effect of hot plasma radiation is due to the decay of a long-living …ONOOH/ONOO-… complex with the formation of a nitric oxide and a nitronium ion in an acidic medium. Nitration plays a decisive role in the sporicidal action of the hot plasma radiation of a spark discharge. The principle of the sporicidal effect of gas-discharge plasma radiation can be used to develop disinfecting devices.