Mycoremediation in Soil

The chapter reviews the most important researches on the use of micro- and macrofungi in the bioremediation of contaminated soils. In particular, the main classes of soil pollutants in Europe (heavy metals, mineral oils, polycyclic aromatic hydrocarbons (PAHs), monoaromatic hydrocarbons, phenols and chlorinated hydrocarbons (CHCs)), together with the emerging contaminants (i.e. endocrine-disrupting chemicals (EDCs) and pharmaceutical-personal care products (PPCPs)) are considered. A description of the fungal species (saprotrophic and biotrophic basidiomycetes) and biodegradative extracellular (laccases and class II peroxidases) and intracellular (cytochrome P450 monooxygenases and glutathione transferases) enzyme classes is reported. Moreover, the chemical-physical parameters that influence the biodegradation process are examined, and the biostimulation and bioaugmentation strategies are described. A specific attention is paid to the microcosm studies, at the laboratory scale, which are an essential approach to evaluate the feasibility of a biodegradation process

Biodegradation of Natural Rubber: Microcosm Study

In the present work, natural rubber (NR) biodegradation, by means of a microbial consortium, naturally selected in a tyre dump soil, has been evaluated. To this purpose, prepared soil microcosms were incubated for 236 days, at room temperature, and natural light/dark cycles. The effect of primary C-source and fresh soil addition, soil aeration, and humidity maintenance, has been monitored by means of microbiological and respirometric analysis, dry weight loss determinations, and SEM micrographs. During the incubation, in biodegradation microcosms (BD), containing NR samples, the produced CO2 was significantly higher than that of biotic controls (BC). Furthermore, after 236 days, a NR dry weight loss of 15.6%, in BD microcosms, was registered, about four-fold higher than that registered in BC control (3.7%). Obtained results confirmed that the naturally selected microbial consortium was able to use NR as the only C source and to biodegrade it. The positive effect of soil mixing evidenced that the biodegradation process was mainly carried out by aerobic biomass, especially filamentous fungi, as confirmed by microbial counts and SEM observations. Results obtained in the microcosm study provided useful information in terms of soil aeration and nutrient amendment in view of a future biodegradation process scale-up

Application of Scenedesmus obliquus in the Treatment of a Real Wastewater

In the present study, the microalga Scenedesmus obliquus CCAP 276/38 has been applied in the treatment of a real wastewater (RWW) derived from an anaerobic digestion process of corn silage and livestock wastewater. The liquid phase of the digestate showed a low viscosity value and a high content of ammonia up to 3 g/L. In a preliminary phase, the experimental tests were carried out in Erlenmeyer flasks in order to identify the optimal RWW concentration and, in particular, its influence on biomass growth and productivity. The tests were carried out at 20°C at an artificial dark/light cycles of 12 hours. Three different concentrations were tested: 1, 2 and 3% of RWW in water, in the presence of sodium bicarbonate (NaHCO3, 50 mM) as inorganic carbon source. The obtained results showed that S. obliquus was able to grow in all the tested RWW concentrations even if a higher growth rate and biomass production were observed in the cultures containing 1% RWW. In order to test the influence of N/P ratio on microalgal growth, two different salts, KNO3 (0,2 g/L) and K2HPO4 (0,02 g/L), were added to the medium containing 1% RWW (N/P = 84.4), to correct the N/P value. The biomass growth rate increased in the medium with the lower N/P value (N/P = 27.9). The microalgal production process was scaled-up in a stirred tank photobioreactor (working volume 5 L), in the same temperature and illumination conditions using a medium with the composition optimized in flask tests. The culture was carried out for 124 hours, fed-batch addition of RWW (1%) was done during the fermentation in order to replace the carbon source. The results (growth rate, biomass dry weight and productivity) were compared with those obtained in presence of a synthetic medium with sodium bicarbonate 50 mM as carbon source. The work clearly demonstrated the capability of S. obliquus CCAP 276/38to grow in alkaline wastewater and the possibility to employ this species in the treatment of effluents containing high ammonia concentratio

Application of Essential Oils to Control the Biodeteriogenic Microorganisms in Archives and Libraries

Microbial contamination control in indoor environments, such as libraries and archives, represents a challenge. Essential oils (EOs), well-known for their antimicrobial properties, have been applied in pharmaceutical and food industry from many years. In the present study, Thymus vulgaris and Origanum vulgare EO antimicrobial efficacy on paper-born microorganisms, Staphylococcus epidermidis, Rhodotorula mucilaginosa and Alternaria alternata, was investigated to protect water-damaged paper documents and to control indoor air quality for operator’s health safety. T. vulgaris EO was the most effective: Minimum Inhibitory Concentration (MIC) values obtained for S. epidermidis and R. mucilaginosa, with a broth macro-dilution method, were 7.5 microgram/mL and 5.63 microgram/mL, respectively. T. vulgaris EO (0.75% v/v), nebulized immediately after the inoculation on agar plates or paper sheets, showed a high inhibition effect against the three biodeteriogenic microorganisms, also when lyophilized on paper sheets; in this last case, the EO has a higher efficacy when applied immediately after the freeze drying. Regarding the EO effect against A. alternata, the inhibition percentage of the mycelial growth, MGI, (81.4%), observed for nonsporulated mycelium, was higher than that for the sporulated one (51.4%). Finally, T. vulgaris EO (0.75% v/v) was effectively applied on a real contaminated book cover by means of EO impregnated contact sheets. Obtained results demonstrated that tested EOs were able to delay or completely inhibit paper-born microorganism growth for both flood-independent or -dependent contamination

Antimicrobial Nano-Zinc Oxide Biocomposites for Wound Healing Applications: A Review

Chronic wounds are a major concern for global health, affecting millions of individuals worldwide. As their occurrence is correlated with age and age-related comorbidities, their incidence in the population is set to increase in the forthcoming years. This burden is further worsened by the rise of antimicrobial resistance (AMR), which causes wound infections that are increasingly hard to treat with current antibiotics. Antimicrobial bionanocomposites are an emerging class of materials that combine the biocompatibility and tissue-mimicking properties of biomacromolecules with the antimicrobial activity of metal or metal oxide nanoparticles. Among these nanostructured agents, zinc oxide (ZnO) is one of the most promising for its microbicidal effects and its anti-inflammatory properties, and as a source of essential zinc ions. This review analyses the most recent developments in the field of nano-ZnO–bionanocomposite (nZnO-BNC) materials—mainly in the form of films, but also hydrogel or electrospun bandages—from the different preparation techniques to their properties and antibacterial and wound-healing performances. The effect of nanostructured ZnO on the mechanical, water and gas barrier, swelling, optical, thermal, water affinity, and drug-release properties are examined and linked to the preparation methods. Antimicrobial assays over a wide range of bacterial strains are extensively surveyed, and wound-healing studies are finally considered to provide a comprehensive assessment framework. While early results are promising, a systematic and standardised testing procedure for the comparison of antibacterial properties is still lacking, partly because of a not-yet fully understood antimicrobial mechanism. This work, therefore, allowed, on one hand, the determination of the best strategies for the design, engineering, and application of n-ZnO-BNC, and, on the other hand, the identification of the current challenges and opportunities for future research

Whey Proteins–Zinc Oxide Bionanocomposite as Antibacterial Films

The use of toxic crosslinking agents and reagents in the fabrication of hydrogels is a frequent issue which is particularly concerning for biomedical or food packaging applications. In this study, novel antibacterial bionanocomposite films were obtained through a simple solvent casting technique without using any crosslinking substance. Films were made from a flexible and transparent whey protein matrix containing zinc oxide nanoparticles synthesised via a wet chemical precipitation route. The physicochemical and functional properties of the ZnO nanoparticles and of the composite films were characterised, and their antibacterial activity was tested against S. epidermidis and E. coli. The synthesised ZnO nanoparticles had an average size of about 30 nm and a specific surface area of 49.5 m(2)/g. The swelling ratio of the bionanocomposite films increased at basic pH, which is an appealing feature in relation to the absorption of chronic wound exudate. A n-ZnO concentration-dependent antibacterial effect was observed for composite films. In particular, marked antibacterial activity was observed against S. epidermidis. Overall, these findings suggest that this novel material can be a promising and sustainable alternative in the design of advanced solutions for wound dressing or food packaging

Repurposing Tempeh Fermentation: a Promising Protein Source Using Food Residues and Edible Filamentous Fungi

Brewers' spent grains (BSG) are the main by-product of the brewery industry, accounting for more than 80 % of total produced by-products. Although this matrix is primarily composed of hemicellulose, cellulose, protein and lignin, the current end-of-life scenario for BSG is as livestock feed. In the present study, a valorisation approach for BSG that uses an edible fungus (Rhizopus oligosporus) in solid state fermentations (SSF) is proposed. First, a microbiological characterization is performed, to shed light on the indigenous microorganisms that are present in the BSG matrix. Then, an appropriate technology approach is used for the SSF that can be conducted both at laboratory and household levels. In the SSF experiments, different temperature (30-35 °C), mass of BSG substrate, inoculum ratio (10 and 15 % v/m) and drilling patters for the aeration of the systems are investigated. The fermentation products were characterized by preparing homogenized samples; it was registered an increase in protein content (5-64%), a slight acidification (ΔpH=0.1-1.2), a decrease of °Brix and the loss of organic matter (and water). The formation of the tempeh cakes was variable, and the differences are analyzed in terms of the operational parameters of each studied batch

Measurements of Protein Content in Aqueous and Alkaline Extracts from Brewer's Spent Grains (bsg): Insights Into the Extraction Kinetics and Energy Consumption

The brewers’ spent grain (BSG) is a rich biomass matrix containing several compounds of interest that require urgent and suitable valorisation strategies, due to its high production volume in the brewing industry. Among the most widespread approaches is the preparation of extracts, targeting particular compounds or soluble and/or insoluble fractions, after operating pre-treatment processes. In the present study, extraction experiments are carried out with fresh untreated BSG, under very gentle extraction conditions (room temperature and moderate agitation, in the 0-5 h interval), and using different solvents: deionized water, 0.1 M NaOH and 0.5 M NaOH in a 1:5 m/v solid-to-solvent ratio. The extraction dynamics were followed by monitoring the dry matter (DM) content obtained in the extracts after a centrifugation step. The protein content is estimated in each case by means of two different methods: direct measurements of absorbance at 280 nm (using bovine serum albumin, BSA, and commercial whey protein isolate as standards) as well as using the Bradford colorimetric method and BSA standard; the consistency of these measurements is contrasted against the DM values. The apparent extraction kinetics were studied, using a saturation model; the coefficients and their range of uncertainty were obtained. Extraction efficiencies in the range 14.24%-53.60% gDM ext/gDM BSG are achieved, which correspond to extraction yields of 38.88-150.09 gDM ext/kg fresh BSG. In addition, the energy footprint of the process is estimated at laboratory scale