Agar Plate Methods for Assessing the Antibacterial Activity of Thyme and Oregano Essential Oils against S. epidermidis and E. coli

The resistance to antimicrobials (AMR), especially antibiotics, represents a serious problem and, at the same time, a challenge. In the last decade, a growing interest in the use of essential oils (EOs) as antimicrobial substances was observed. Commercial thyme and oregano EOs are reported to be the main responsible of the oil antimicrobial efficacy against both Gram-positive and Gramnegative pathogenic bacteria. The aim of the present work was to study the efficacy of EOs against Staphylococcus epidermidis and Escherichia coli in long-time treatments. In a preliminary microdilution test, a MIC value was obtained for thyme EO against S. epidermidis and E. coli. After that, disk diffusion and disk volatilization tests were set up to study the influence of main cultural parameters on EO activity in liquid or vapor phase. Both bacteria were inhibited by thyme and oregano EOs when applied pure (100% v/v) or diluted (75% and 50% v/v): a higher inhibition was observed in a disk diffusion test in which the antimicrobial effect was due to both liquid and vapor phase components. Finally, a comparison with literature data was carried out even if it was not so easy because standard methods are usually modified and adapted to specific case study. For this reason, the results have to be interpreted in relation to the analytical method applied

Antibacterial β-Glucan/Zinc Oxide Nanocomposite Films for Wound Healing

Advanced antimicrobial biomaterials for wound healing applications are an active field of research for their potential in addressing severe and infected wounds and overcoming the threat of antimicrobial resistance. Beta-glucans have been used in the preparation of these materials for their bioactive properties, but very little progress has been made so far in producing biomedical devices entirely made of beta-glucans and in their integration with effective antimicrobial agents. In this work, a simple and eco-friendly method is used to produce flexible beta-glucan/nanostructured zinc oxide films, using glucans derived from the yeast Saccharomyces cerevisiae. The properties of the films are characterized through scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, infrared and UV–visible spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and water absorption tests. Finally, the antibacterial properties of the nanostructured zinc oxide and of the composite films are assessed against Staphylococcus epidermidis and Escherichia coli, showing a marked effectiveness against the former. Overall, this study demonstrates how a novel bionanocomposite can be obtained towards the development of advanced wound healing devices

On the effect of freeze-drying on paper-borne microorganisms

Today there is an ever-increasing interest in recovering flooded archival materials. Freeze-drying stands out as a valuable method as the water is frozen and the ice is then removed through sublimation. The present work is focused on the effect of freeze-drying on flooded paper contaminated with biodeteriogenic microorganisms (i.e. a bacterium Staphylococcus epidermidis, a yeast Rhodotorula mucilaginosa and a filamentous fungus Alternaria alternata). The effect of freezing and drying on microorganism survival and growth has been separately evaluated. In particular, different operative conditions for freezing (in a domestic freezer at about -20°C, at -40°C with a freezing rate of -1°C/min) and drying (200 μbar at 0°C and 20°C) have been tested. All the tested strains were able to survive after freezing and drying phases, nevertheless a different behaviour was observed: the growth of S. epidermidis was the same as that of the control, R. mucilaginosa showed a slight growth and carotenoid production increase, while A. alternata was inhibited, in particular after the freezing at -40°C, followed by a low temperature drying rate step

Mycotoxins: Are They Perceived as a Serious Threat for the Human Health?

Mycotoxins contamination and the associated risks are well known from the scientific community as it is possible to desume from the huge amount of the related scientific publications. Although the threat for human and animal health is really high and the worldwide diffusion of the contamination is for the most part uncontrollable, the public opinion is not really conscious of the problem and sometimes ignores it. In the present paper, a brief description of different aspects related to mycotoxins contamination is reported as regard toxicology and risks for the health, recent European and global regulations, and laboratory methods for mycotoxins determination

Natural rubber biodegradation by Alternaria alternata and Penicillium chrysogenum isolates

In the present work, the biodegradation of natural rubber by means of three filamentous fungi, two Alternaria alternata strains (ANR and BNR) and Penicillium chrysogenum, is reported. The biodegradation process has been optimized in Erlenmeyer flasks and then scaled-up in Fernbach flasks. The biodegradation was performed in stationary liquid cultures with biomass immobilized on ceramic Berl saddles. In the presence of NR as the only carbon source, the maximum value of enzyme activity (0.242 IU/L) was reached at 41 days of incubation and at the end of incubation time, 65 days, a 2% weight loss of NR was detected. In Fernbach flasks, the maximum peroxidase activity value was doubled (0.500 IU/L) and reached earlier, after 6 days. In the same incubation time, a better biodegradation performance (4.3%) was obtained. Moreover, the application of a double biodegradation step allowed to obtain higher biodegradation percentage, 6.8%. Among the different tested microorganisms, A. alternata BNR showed the best biodegradation potentiality in terms of enzyme production and NR degradation. On the basis of the results obtained in liquid cultures, A. alternata BNR is currently applied in a lab-scale microcosm study which has to be considered the preliminary step of an in-field biodegradation process

Il recupero delle pectine da bucce di fave di cacao

Le bucce delle fave di cacao, uno scarto tipico della produzione del cioccolato, possono essere valorizzate come fonte per la produzione di pectine, additivi gelificanti di largo impiego. Nel presente lavoro vengono presentati i risultati relativi allo sviluppo e all’ottimizzazione, su scala di laboratorio, dell’estrazione delle pectine da questi scarti. Lo studio del processo è avvenuto sulla base di quello tradizionalmente utilizzato per le produzioni industriali. Dallo studio è emerso che la migliore resa è ottenuta con una estrazione effettuata a pH 2,5 a 95°C per 1 ora; le pectine così prodotte sono caratterizzate da un basso grado di metilesterificazione e di acetilazione. I buoni risultati ottenuti costituiscono la base per un ulteriore approfondimento volto a rendere competitivo il processo in termini di resa, economia e qualità del prodotto finale

Characterization of confectionary products containing chocolate and hazelnuts

The analysis of numerous conched chocolate samples and roasted hazelnuts has allowed to point out the fundamental aromatic constituents and to undertake a chemical interpretation of the final product taste. It has been experienced that the concentrations of these constituents, also those unpleasant, in the raw materials can be controlled by means of the thermal operations condition