Anti-Bacterial Adhesion on Abiotic and Biotic Surfaces of the Exopolysaccharide from the Marine Bacillus licheniformis B3-15.

The eradication of bacterial biofilm represents a crucial strategy to prevent a clinical problem associated with microbial persistent infection. In this study we evaluated the ability of the exopolysaccharide (EPS) B3-15, produced by the marine Bacillus licheniformis B3-15, to prevent the adhesion and biofilm formation of Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213 on polystyrene and polyvinyl chloride surfaces. The EPS was added at different times (0, 2, 4 and 8 h), corresponding to the initial, reversible and irreversible attachment, and after the biofilm development (24 or 48 h). The EPS (300 µg/mL) impaired the initial phase, preventing bacterial adhesion even when added after 2 h of incubation, but had no effects on mature biofilms. Without exerting any antibiotic activity, the antibiofilm mechanisms of the EPS were related to the modification of the (i) abiotic surface properties, (ii) cell-surface charges and hydrophobicity, and iii) cell-to-cell aggregation. The addition of EPS downregulated the expression of genes (lecA and pslA of P. aeruginosa and clfA of S. aureus) involved in the bacterial adhesion. Moreover, the EPS reduced the adhesion of P. aeruginosa (five logs-scale) and S. aureus (one log) on human nasal epithelial cells. The EPS could represent a promising tool for the prevention of biofilm-related infections.

Antimicrobial and Antibiofilm Photodynamic Action of Photosensitizing Nanoassemblies Based on Sulfobutylether-ß-Cyclodextrin.

Developing new broad-spectrum antimicrobial strategies, as alternatives to antibiotics and being able to efficiently inactivate pathogens without inducing resistance, is one of the main objectives in public health. Antimicrobial photodynamic therapy (aPDT), based on the light-induced production of reactive oxygen species from photosensitizers (PS), is attracting growing interest in the context of infection treatment, also including biofilm destruction. Due to the limited photostability of free PS, delivery systems are increasingly needed in order to decrease PS photodegradation, thus improving the therapeutic efficacy, as well as to reduce collateral effects on unaffected tissues. In this study, we propose a photosensitizing nanosystem based on the cationic porphyrin 5,10,15,20-tetrakis (N-methyl- 4-pyridyl)-21H,23H-porphyrin (TMPyP), complexed with the commerical sulfobutylether-beta-cyclodextrin (CAPTISOL®), at a 1:50 molar ratio (CAPTISOL®/TMPyP)50_1. Nanoassemblies based on (CAPTISOL®/TMPyP)50_1 with photodynamic features exhibited photo-antimicrobial activity against Gram-negative and Gram-positive bacteria. Moreover, results from P. aeruginosa reveal that CAPTISOL® alone inhibits pyocyanin (PYO) production, also affecting bacterial biofilm formation. Finally, we obtained a synergistic effect of inhibition and destruction of P. aeruginosa biofilm by using the combination of CAPTISOL® and TMPyP.

Nutritional conditions of the novel freshwater Coccomyxa AP01 for versatile fatty acids composition.

AIMS: This study was to analyse the biomass production and fatty acids (FAs) profiles in a newly isolated chlorophyte, namely Coccomyxa AP01, under nutritionally balanced (NB) conditions (comparing nitrate and urea as nitrogen sources) and nitrogen or phosphate deprivation. METHODS AND RESULTS: Lipid yields was about 30%-40% of dried biomasses in all examined nutritional conditions. Under NB conditions, lipids were principally constituted by monounsaturated FAs, mainly represented by oleic acid, and saturated and polyunsaturated FAs at similar concentrations. Nutrients deprivation induced remarkable changes in FAs profiles, with the highest amounts of saturated (42%-46%), followed by similar amounts of monounsaturated and polyunsaturated, and the emergence of rare long-chain FAs. Under phosphate deprivation, biomass yield was similar to NB conditions, with the highest yield of saturated (mainly palmitic acid) and of polyunsaturated FAs (33%) (mainly linoleic and linolenic acids). CONCLUSIONS: Balanced or deprived nutritional conditions in Coccomyxa AP01 induced a selective production and composition of FAs. The phosphate-deprivation condition concomitantly provided high biomass yield and the production of high value saturated and polyunsaturated FAs with industrial interest. SIGNIFICANCE AND IMPACT OF THE STUDY: Coccomyxa AP01 could be considered a promising source of different FAs, including also docosapentaenoic acid, for several commercial purposes spanning from biodiesel production, pharmaceutical and cosmetic applications to innovative aquaculture fish feeds.

Applications of CRISPR-Cas9 in Alzheimer's Disease and Related Disorders.

Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease represent some of the most prevalent neurodegenerative disorders afflicting millions of people worldwide. Unfortunately, there is a lack of efficacious treatments to cure or stop the progression of these disorders. While the causes of such a lack of therapies can be attributed to various reasons, the disappointing results of recent clinical trials suggest the need for novel and innovative approaches. Since its discovery, there has been a growing excitement around the potential for CRISPR-Cas9 mediated gene editing to identify novel mechanistic insights into disease pathogenesis and to mediate accurate gene therapy. To this end, the literature is rich with experiments aimed at generating novel models of these disorders and offering proof-of-concept studies in preclinical animal models validating the great potential and versatility of this gene-editing system. In this review, we provide an overview of how the CRISPR-Cas9 systems have been used in these neurodegenerative disorders.

Multipotential Role of Growth Factor Mimetic Peptides for Osteochondral Tissue Engineering.

Articular cartilage is characterized by a poor self-healing capacity due to its aneural and avascular nature. Once injured, it undergoes a series of catabolic processes which lead to its progressive degeneration and the onset of a severe chronic disease called osteoarthritis (OA). In OA, important alterations of the morpho-functional organization occur in the cartilage extracellular matrix, involving all the nearby tissues, including the subchondral bone. Osteochondral engineering, based on a perfect combination of cells, biomaterials and biomolecules, is becoming increasingly successful for the regeneration of injured cartilage and underlying subchondral bone tissue. To this end, recently, several peptides have been explored as active molecules and enrichment motifs for the functionalization of biomaterials due to their ability to be easily chemically synthesized, as well as their tunable physico-chemical features, low immunogenicity issues and functional group modeling properties. In addition, they have shown a good aptitude to penetrate into the tissue due to their small size and stability at room temperature. In particular, growth-factor-derived peptides can play multiple functions in bone and cartilage repair, exhibiting chondrogenic/osteogenic differentiation properties. Among the most studied peptides, great attention has been paid to transforming growth factor-ß and bone morphogenetic protein mimetic peptides, cell-penetrating peptides, cell-binding peptides, self-assembling peptides and extracellular matrix-derived peptides. Moreover, recently, phage display technology is emerging as a powerful selection technique for obtaining functional peptides on a large scale and at a low cost. In particular, these peptides have demonstrated advantages such as high biocompatibility; the ability to be immobilized directly on chondro- and osteoinductive nanomaterials; and improving the cell attachment, differentiation, development and regeneration of osteochondral tissue. In this context, the aim of the present review was to go through the recent literature underlining the importance of studying novel functional motifs related to growth factor mimetic peptides that could be a useful tool in osteochondral repair strategies. Moreover, the review summarizes the current knowledge of the use of phage display peptides in osteochondral tissue regeneration.

Role of Phage Capsid in the Resistance to UV-C Radiations.

The conformational variation of the viral capsid structure plays an essential role both for the environmental resistance and acid nuclear release during cellular infection. The aim of this study was to evaluate how capsid rearrangement in engineered phages of M13 protects viral DNA and peptide bonds from damage induced by UV-C radiation. From in silico 3D modelling analysis, two M13 engineered phage clones, namely P9b and 12III1, were chosen for (i) chemical features of amino acids sequences, (ii) rearrangements in the secondary structure of their pVIII proteins and (iii) in turn the interactions involved in phage capsid. Then, their resistance to UV-C radiation and hydrogen peroxide (H2O2) was compared to M13 wild-type vector (pC89) without peptide insert. Results showed that both the phage clones acquired an advantage against direct radiation damage, due to a reorganization of interactions in the capsid for an increase of H-bond and steric interactions. However, only P9b had an increase in resistance against H2O2. These results could help to understand the molecular mechanisms involved in the stability of new virus variants, also providing quick and necessary information to develop effective protocols in the virus inactivation for human activities, such as safety foods and animal-derived materials.

Antimicrobial Effect and Cytotoxic Evaluation of Mg-Doped Hydroxyapatite Functionalized with Au-Nano Rods.

Hydroxyapatite (HA) is the main inorganic mineral that constitutes bone matrix and represents the most used biomaterial for bone regeneration. Over the years, it has been demonstrated that HA exhibits good biocompatibility, osteoconductivity, and osteoinductivity both in vitro and in vivo, and can be prepared by synthetic and natural sources via easy fabrication strategies. However, its low antibacterial property and its fragile nature restricts its usage for bone graft applications. In this study we functionalized a MgHA scaffold with gold nanorods (AuNRs) and evaluated its antibacterial effect against S. aureus and E. coli in both suspension and adhesion and its cytotoxicity over time (1 to 24 days). Results show that the AuNRs nano-functionalization improves the antibacterial activity with 100% bacterial reduction after 24 h. The toxicity study, however, indicates a 4.38-fold cell number decrease at 24 days. Although further optimization on nano-functionalization process are needed for cytotoxicity, these data indicated that Au-NRs nano-functionalization is a very promising method for improving the antibacterial properties of HA.

Analysis of Pseudo-Lyapunov Exponents of Solar Convection Using State-of-the-Art Observations.

The solar photosphere and the outer layer of the Sun's interior are characterized by convective motions, which display a chaotic and turbulent character. In this work, we evaluated the pseudo-Lyapunov exponents of the overshooting convective motions observed on the Sun's surface by using a method employed in the literature to estimate those exponents, as well as another technique deduced from their definition. We analyzed observations taken with state-of-the-art instruments at ground- and space-based telescopes, and we particularly benefited from the spectro-polarimetric data acquired with the Interferometric Bidimensional Spectrometer, the Crisp Imaging SpectroPolarimeter, and the Helioseismic and Magnetic Imager. Following previous studies in the literature, we computed maps of four quantities which were representative of the physical properties of solar plasma in each observation, and estimated the pseudo-Lyapunov exponents from the residuals between the values of the quantities computed at any point in the map and the mean of values over the whole map. In contrast to previous results reported in the literature, we found that the computed exponents hold negative values, which are typical of a dissipative regime, for all the quantities derived from our observations. The values of the estimated exponents increase with the spatial resolution of the data and are almost unaffected by small concentrations of magnetic field. Finally, we showed that similar results were also achieved by estimating the exponents from residuals between the values at each point in maps derived from observations taken at different times. The latter estimation technique better accounts for the definition of these exponents than the method employed in previous studies.

Glutamine-induced filamentous cells of Pseudomonas mediterranea CFBP-5447T as producers of PHAs.

Polyhydroxyalkanoates (PHAs) are considerable biopolymers that have gained an increasing biotechnological interest in different applications, although their industrial production presents several limitations. Filamentous bacterial cells could represent a possible strategy to increase PHA yield, since more abundant PHA inclusions can be stored in elongated than in rod-shaped cells. At first, we determined the optimal batch culture conditions to induce filamentation in Pseudomonas mediterranea CFBP-5447T, using glutamine, glycerol, glucose, and sodium octanoate, as the sole carbon source, at low- (100 rpm) or high- (250 rpm) shaking speeds. Successively, a fermentative process was set up using glutamine in a co-metabolic strategy with glycerol, and the PHAs production was compared in rod-shaped and filamentous cells. High glutamine concentrations (from 28 to 56 mM) were able to induce alone filamentation, whereas at lower glutamine concentrations (5-10 mM), the shaking speeds became critical to allow or not filamentous phenotype. PHA granule production was higher in filamentous than in rod-shaped cells, when glycerol (46.6 mM) was added to glutamine (5 mM) in co-metabolism, and fermentation was performed at a low-shaking speed. After extraction and precipitation, PHA yield was about two times higher in filamentous than that rod-shaped cells. Our results provide new insights into filament-inducing conditions and indicate a potential use of filamentous P. mediterranea CFBP-5447T cells to increase PHA yield. These findings could have great advantages in PHAs recovering during downstream processes, since the harvesting of elongated cells is much less time-consuming and energy expensive than required with rod-shaped cells.

Poly(carboxylic acid)-Cyclodextrin/Anionic Porphyrin Finished Fabrics as Photosensitizer Releasers for Antimicrobial Photodynamic Therapy.

In the development of new antibacterial therapeutic approaches to fight multidrug-resistant bacteria, antimicrobial photodynamic therapy (aPDT) represents a well-known alternative to treat local infections caused by different microorganisms. Here we present a polypropylene (PP) fabric finished with citrate-hydroxypropyl-ßCD polymer (PP-CD) entrapping the tetra-anionic 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (TPPS) as photosensitizer-eluting scaffold (PP-CD/TPPS) for aPDT. The concept is based on host-guest complexation of porphyrin in the cavities of CDs immobilized on the PP fibers, followed by its sustained and controlled delivery in release medium and simultaneous photoinactivation of microorganisms. Morphology of fabric was characterized by optical (OM) and scanning electron microscopies (SEM). Optical properties were investigated by UV-vis absorption, steady- and time-resolved fluorescence emission spectroscopy. X-ray photoelectron spectroscopy (XPS) and FT-IR revealed the surface chemical composition and the distribution map of the molecular components on the fabric, respectively. Direct 1O2 determination allowed to assess the potential photodynamic activity of the fabric. Release kinetics of TPPS in physiological conditions pointed out the role of the CD cavity to control the TPPS elution. Photoantimicrobial activity of the porphyrin-loaded textile was investigated against both Gram-positive Staphylococcus aureus ATCC 29213 (S. aureus) and Gram-negative Pseudomonas aeruginosa ATCC 27853 (P. aeruginosa). Optical microscopy coupled with UV-vis extinction and fluorescence spectra aim to ascertain the uptake of TPPS to S. aureus bacterial cells. Finally, PP-CD/TPPS fabric-treated S. aureus cells were photokilled of 99.98%. Moreover, low adhesion of S. aureus cells on textile was established. Conversely, no photodamage of fabric-treated P. aeruginosa cells was observed, together with their satisfying adhesion.

A water-soluble pillar[5]arene as a new carrier for an old drug.

The remarkable affinity of deca-carboxylatopillar[5]arene WP5 towards the aminoglycoside antibiotic, amikacin, in aqueous media is reported; in vitro studies on Gram-positive bacteria (Staphylococcus aureus) show that drug entrapment inside WP5 also takes place in the presence of the microrganisms, thus pointing to WP5 as an appealing carrier for amikacin targeted delivery.

Matrix-assisted laser desorption/ionization time-of-flight vs. fast-atom bombardment and electrospray ionization mass spectrometry in the structural characterization of bacterial poly(3-hydroxyalkanoates).

RATIONALE: Bacterial poly(3-hydroxyalkanoates) (PHAs) are an emergent class of plastic materials available from renewable resources. Their properties are strictly correlated with the comonomeric composition and sequence, which may be determined by various mass spectrometry approaches. In this paper we compare fast-atom bombardment (FAB) and electrospray ionization (ESI) to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) of partially pyrolyzed samples. METHODS: We determined the compositions and sequences of the medium-chain-length PHAs (mcl-PHAs) prepared by bacterial fermentation of Pseudomonas aeruginosa ATCC 27853 cultured in media containing fatty acids with 8, 12, 14, 18, and 20 carbon atoms as carbon sources by means of MALDI-TOFMS of pyrolyzates, and compared the results with those obtained by FAB- and ESI-MS in previous studies. MALDI matrices used were 9-aminoacridine (9-AA) and indoleacrylic acid (IAA). RESULTS: MALDI-TOFMS was carried out in negative ion mode when using 9-AA as a matrix, giving a semi-quantitative estimation of the 3-hydroxyacids constituting the PHAs, and in positive mode when using IAA, allowing us, through statistical analysis of the relative intensity of the oligomers generated by pyrolysis, to establish that the polymers obtained are true random copolyesters and not a mixture of homopolymers or copolymers. CONCLUSIONS: MALDI-TOFMS in 9-AA and IAA of partial pyrolyzates of mcl-PHAs represents a powerful method for the structural analysis of these materials. In comparison with FAB and ESI, MALDI provided an extended mass range with better sensitivity at higher mass and a faster method of analysis.

Generation of a helper phage for the fluorescent detection of peptide-target interactions by dual-display phages.

Phage display is a molecular biology technique that allows the presentation of foreign peptides on the surface of bacteriophages. It is widely utilized for applications such as the discovery of biomarkers, the development of therapeutic antibodies, and the investigation of protein-protein interactions. When employing phages in diagnostic and therapeutic monitoring assays, it is essential to couple them with a detection system capable of revealing and quantifying the interaction between the peptide displayed on the phage capsid and the target of interest. This process is often technically challenging and costly. Here, we generated a fluorescent helper phage vector displaying sfGFP in-frame to the pIII of the capsid proteins. Further, we developed an exchangeable dual-display phage system by combining our newly developed fluorescent helper phage vector with a phagemid vector harboring the engineered pVIII with a peptide-probe. By doing so, the sfGFP and a peptide-probe are displayed on the same phage particle. Notably, our dual-display approach is highly flexible as it allows for easy exchange of the displayed peptide-probe on the pVIII to gain the desired selectivity, while maintaining the sfGFP gene, which allows easy visualization and quantification of the interaction peptide-probe. We anticipate that this system will reduce time and costs compared to the current phage-based detection systems.

Lichenysin-like Polypeptide Production by Bacillus licheniformis B3-15 and Its Antiadhesive and Antibiofilm Properties.

We report the ability of the crude biosurfactant (BS B3-15), produced by the marine, thermotolerant Bacillus licheniformis B3-15, to hinder the adhesion and biofilm formation of Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213 to polystyrene and human cells. First, we attempted to increase the BS yield, optimizing the culture conditions, and evaluated the surface-active properties of cell-free supernatants. Under phosphate deprivation (0.06 mM) and 5% saccharose, the yield of BS (1.5 g/L) increased by 37%, which could be explained by the earlier (12 h) increase in lchAA expression compared to the non-optimized condition (48 h). Without exerting any anti-bacterial activity, BS (300 µg/mL) prevented the adhesion of P. aeruginosa and S. aureus to polystyrene (47% and 36%, respectively) and disrupted the preformed biofilms, being more efficient against S. aureus (47%) than P. aeruginosa (26%). When added to human cells, the BS reduced the adhesion of P. aeruginosa and S. aureus (10× and 100,000× CFU/mL, respectively) without altering the epithelial cells' viability. As it is not cytotoxic, BS B3-15 could be useful to prevent or remove bacterial biofilms in several medical and non-medical applications.

Structural and antibacterial studies of novel ZnO and ZnxMn(1-x)O nanostructured titanium scaffolds for biomedical applications.

In the biomedical field, the demand for the development of broad-spectrum biomaterials able to inhibit bacterial growth is constantly increasing. Chronic infections represent the most serious and devastating complication related to the use of biomaterials. This is particularly relevant in the orthopaedic field, where infections can lead to implant loosening, arthrodesis, amputations and sometimes death. Antibiotics are the conventional approach for implanted-associated infections, but they have the limitation of increasing antibiotic resistance, a critical worldwide healthcare issue. In this context, the development of anti-infective biomaterials and infection-resistant surfaces can be considered the more effective strategy to prevent the implant colonisation and biofilm formation by bacteria, so reducing the occurrence of implant-associated infections. In the last years, inorganic nanostructures have become extremely appealing for chemical modifications or coatings of Ti surfaces, since they do not generate antibiotic resistance issues and are featured by superior stability, durability, and full compatibility with the sterilization process. In this work, we present a simple, rapid, and cheap chemical nanofunctionalization of titanium (Ti) scaffolds with colloidal ZnO and Mn-doped ZnO nanoparticles (NPs), prepared by a sol-gel method, exhibiting antibacterial activity. ZnO NPs and ZnxMn(1-x)O NPs formation with a size around 10-20nm and band gap values of 3.42 eV and 3.38 eV, respectively, have been displayed by characterization studies. UV-Vis, fluorescence, and Raman investigation suggested that Mn ions acting as dopants in the ZnO lattice. Ti scaffolds have been functionalized through dip coating, obtaining ZnO@Ti and ZnxMn(1-x)O@Ti biomaterials characterized by a continuous nanostructured film. ZnO@Ti and ZnxMn(1-x)O@Ti displayed an enhanced antibacterial activity against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa) bacterial strains, compared to NPs in solution with better performance of ZnxMn(1-x)O@Ti respect to ZnO@Ti. Notably, it has been observed that ZnxMn(1-x)O@Ti scaffolds reach a complete eradication for S. aureus and 90 % of reduction for P. aeruginosa. This can be attributed to Zn2+ and Mn2+ metal ions release (as observed by ICP MS experiments) that is also maintained over time (72 h). To the best of our knowledge, this is the first study reported in the literature describing ZnO and Mn-doped ZnO NPs nanofunctionalized Ti scaffolds with improved antibacterial performance, paving the way for the realization of new hybrid implantable devices through a low-cost process, compatible with the biotechnological industrial chain method.

A Novel Serum-Based Diagnosis of Alzheimer's Disease Using an Advanced Phage-Based Biochip.

55 million people worldwide suffer from Alzheimer's disease (AD). A definitive diagnosis of AD is made postmortem after a neuropathological examination of the brain. There is an urgent need for an innovative, noninvasive methodology that allows for an early and reliable diagnosis. Several engineered phages that recognized Aß-autoantibodies present in the sera of AD patients are previously identified. Here, novel phages are tested for their ability to accurately discriminate AD sera using immunophage-polymerase chain reaction in a miniatured biochip. It is found that five of the six phages analyzed discriminate between healthy controls and AD patients. Further, by combining the response of two phages, non-AD and severe AD cases are identified with 100% accuracy and mild-to-moderate cases with 90% accuracy. While the number of cases used here are relatively small and can be confirmed in larger cohorts, this first-of-a-kind system represents an innovative methodology with the potential of having a major impact in the AD field: from a clinical perspective, it can aid physicians in making an accurate AD diagnosis; from a research perspective, it can be used as a surrogate for AD clinical trials.

Metal-Based Nanoparticles: Antibacterial Mechanisms and Biomedical Application.

The growing increase in antibiotic-resistant bacteria has led to the search for new antibacterial agents capable of overcoming the resistance problem. In recent years, nanoparticles (NPs) have been increasingly used to target bacteria as an alternative to antibiotics. The most promising nanomaterials for biomedical applications are metal and metal oxide NPs, due to their intrinsic antibacterial activity. Although NPs show interesting antibacterial properties, the mechanisms underlying their action are still poorly understood, limiting their use in clinical applications. In this review, an overview of the mechanisms underlying the antibacterial activity of metal and metal oxide NPs will be provided, relating their efficacy to: (i) bacterial strain; (ii) higher microbial organizations (biofilm); (iii) and physico-chemical properties of NPs. In addition, bacterial resistance strategies will be also discussed to better evaluate the feasibility of the different treatments adopted in the clinical safety fields. Finally, a wide analysis on recent biomedical applications of metal and metal oxide NPs with antibacterial activity will be provided.

Evaluation of Betacoronavirus OC43 and SARS-CoV-2 Elimination by Zefero Air Sanitizer Device in a Novel Laboratory Recirculation System.

Indoor air sanitizers contrast airborne diseases and particularly severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/Coronavirus disease 2019 (COVID-19). The commercial air sanitizer Zefero (Cf7 S.r.l., San Giovanni La Punta, Italy) works alternatively using a set of integrated disinfecting technologies (namely Photocatalysis/UV mode) or by generating ozone (Ozone mode). Here we evaluated the virucidal efficacy of Zefero setup modes against human Betacoronavirus OC43 and SARS-CoV-2. For this purpose, we designed a laboratory test system in which each virus, as aerosol, was treated with Photocatalysis/UV or Ozone mode and returned into a recirculation plexiglass chamber. Aerosol samples were collected after different times of exposure, corresponding to different volumes of air treated. The viral RNA concentration was determined by qRT-PCR. In Photocatalysis/UV mode, viral RNA of OC43 or SARS-CoV-2 was not detected after 120 or 90 min treatment, respectively, whereas in Ozone mode, viruses were eliminated after 30 or 45 min, respectively. Our results indicated that the integrated technologies used in the air sanitizer Zefero are effective in eliminating both viruses. As a reliable experimental system, the recirculation chamber developed in this study represents a suitable apparatus for effectively comparing the disinfection capacity of different air sanitizers.

Physicochemical Characterization and Antibacterial Properties of Carbon Dots from Two Mediterranean Olive Solid Waste Cultivars.

Carbon nanomaterials have shown great potential in several fields, including biosensing, bioimaging, drug delivery, energy, catalysis, diagnostics, and nanomedicine. Recently, a new class of carbon nanomaterials, carbon dots (CDs), have attracted much attention due to their easy and inexpensive synthesis from a wide range of precursors and fascinating physical, chemical, and biological properties. In this work we have developed CDs derived from olive solid wastes of two Mediterranean regions, Puglia (CDs_P) and Calabria (CDs_C) and evaluated them in terms of their physicochemical properties and antibacterial activity against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). Results show the nanosystems have a quasi-spherical shape of 12-18 nm in size for CDs_P and 15-20 nm in size for CDs_C. UV-Vis characterization indicates a broad absorption band with two main peaks at about 270 nm and 300 nm, respectively, attributed to the π-π* and n-π* transitions of the CDs, respectively. Both samples show photoluminescence (PL) spectra excitation-dependent with a maximum at λem = 420 nm (λexc = 300 nm) for CDs_P and a red-shifted at λem = 445 nm (λexc = 300 nm) for CDs_C. Band gaps values of ≈ 1.48 eV for CDs_P and ≈ 1.53 eV for CDs_C are in agreement with semiconductor behaviour. ζ potential measures show very negative values for CDs_C compared to CDs_P (three times higher, -38 mV vs. -18 mV at pH = 7). The evaluation of the antibacterial properties highlights that both CDs have higher antibacterial activity towards Gram-positive than to Gram-negative bacteria. In addition, CDs_C exhibit bactericidal behaviour at concentrations of 360, 240, and 120 µg/mL, while lesser activity was found for CDs_P (bacterial cell reduction of only 30% at the highest concentration of 360 µg/mL). This finding was correlated to the higher surface charge of CDs_C compared to CDs_P. Further investigations are in progress to confirm this hypothesis and to gain insight on the antibacterial mechanism of both cultivars.

Viable but nonculturable state of foodborne pathogens in grapefruit juice: a study of laboratory.

Several foodborne human pathogens, when exposed to harsh conditions, enter viable but nonculturable (VBNC) state; however, still open is the question whether VBNC pathogens could be a risk for public health, because, potentially, they can resuscitate. Moreover, cultural methods for food safety control were not able to detect VBNC forms of foodborne bacteria. Particularly, it has not been established whether food chemophysical characteristics can induce VBNC state in contaminating pathogen bacterial populations, especially in food, such as salads and fresh fruit juices, not subjected to any decontamination treatment. In this preliminary study, we intentionally contaminated grapefruit juice to determine whether pathogen bacteria could enter VNBC state. In fact, grapefruit juice contains natural antimicrobial compounds, has an average pH of about 3 and low content in carbohydrates. Such characteristics make grapefruit juice a harsh environment for microbial survival. For this purpose, Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium ATCC 14028, Listeria monocytogenes ATCC 7644, and Shigella flexneri ATCC 12022, at two different inoculum sizes, have been used. Viability by the LIVE/DEAD BacLight Bacterial Viability kit and culturability by plate counts assay were monitored, whereas "resuscitation" of nonculturable populations was attempted by inoculation in nutrient-rich media. The data showed that L. monocytogenes lost both culturability and viability and did not resuscitate within 24 h independently on inoculum size, whereas E. coli O157:H7 was able to resuscitate after 24 h but did not after 48 h. Salmonella Typhimurium and S. flexneri, depending on inoculum size, lost culturability but maintained viability and were able to resuscitate; moreover, S. flexneri was still able to form colonies after 48 h at high inoculum size. In conclusion, entry into VBNC state differs on the species, depending, in turn, on inoculum size and time of incubation.