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.

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.

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.

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.

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.

A multivariate analysis of Multiple Myeloma subtype plasma cells.

Trusted methods for identifying different Multiple Myeloma (MM) cells and their biological diversity due to their immunophenotypic variety are often little detailed and difficult to find in literature. In this work, we show that micro-Raman spectroscopy can be used to highlight if there is a certain degree of distinction or correlation between the MM subtype plasmacells in relation to the cluster of differentiation (CD45+/CD38+/CD138-) and (CD45-/CD38+/CD138+). After taking samples from the bone marrow of patients with Multiple Myeloma, the PCs were sorted by flow cytometry, selecting the most common CD of the disease, i.e. CD 45, CD38 and CD138. Some spectral differences are observed comparing the Raman spectra of the two set of samples investigated. To better define in which spectral regions there are greater differences and, therefore, to which biological contributions the changes refers, we also explored the principal component analysis (PCA) of the collected Raman data. The spectral variations between the different sorted cells have been highlighted by plotting loading vectors PC1 and PC2, which shows a net differentiation between the two set of cells. Ultimately, the differences shown by PCA have been associated with the spectral variations observed and explained in terms of changes of proteins and lipid contributions. Thus, the differentiation of Multiple Myeloma subtype plasma cells by confocal micro-Raman spectroscopy can be proposed as a diagnostic tool in the speeding up of cell identification, assessing the intracellular biochemical changes that take place in cancer cells.

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.