Background: Plastic is one of the most widely used materials worldwide in various fields, including packaging and agriculture. Its large quantities require proper disposal and for this reason more and more attention is paid to the issue of degrading plastic. Thanks to the production of non-specific enzymes, fungi are able to attack complex and recalcitrant xenobiotics such as plastics. In recent years, several spectroscopic methods were used to study the plastic degradation ability of different fungal species. Among these, Fourier transform infrared (FT-IR) and FT-Raman spectroscopy techniques are the most used. Surface-enhanced Raman scattering (SERS) spectroscopy is a powerful technique which uses metal nanoparticles (NPs) to enhance the Raman signal of molecules adsorbed on the NPs surface. In this work, the isolation of different fungi from field-collected plastic debris and the ability of these isolates to growth and colonizing the low-density polyethylene (LDPE) were explored by using scanning electron microscope (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and SERS spectroscopies. Results: Forty-seven fungal isolates belonging to 10 genera were obtained; among them only 11 were able to grow and colonize the LDPE film. However, after 90 days trial, only one isolate of Cladosporium cladosporioides (Clc/1) was able to carry out the initial degradation of the LDPE film. In particular, based on SEM observations, small cavities and depressed areas of circular shape were visible in the treated samples. Additionally, ATR-FTIR, normal Raman and SERS analyses supported the structural changes observed via SEM. Notably, ATR-FTIR and normal Raman spectra showed a significant decrease in the relative intensity of the methylene group bands. Similarly, the SERS spectra of LDPE after the fungal attack, confirmed the decrease of methylene groups bands and the appearance of other bands referring to LDPE polyphenolic admixtures. Conclusions: These results suggest that Cladosporium cladosporioides Clc/1 is able to carry out an initial degradation of LDPE. Moreover, combining ATR-FTIR, Raman and SERS spectroscopies with SEM observations, the early stages of LDPE degradation can be explored without any sample pretreatment. Graphical

Cyanobacteria phycobiliproteins (PBPs) are already exploited in the food industries and for biotechnological applications but not in the agricultural field. Different concentrations (0.6 – 4.8 mg/mL) of Anabaena minutissima PBPs were applied to tomato seed to study their priming effect against the soil-borne fungal pathogen Rhizoctonia solani and in promoting plant growth. PBPs increased seedling emergence and vigour, showed activity against root rot disease (67%), and enhanced plant dry weight, length, and height. Generally, no dose effect has been observed except for dry weight (55% at 4.8 mg/mL). Seed treatment primed seeds and seedlings by leading to the activation of defence responses raising phenol (26% in hypocotyls) and flavonoid (26 and 45% in hypocotyls and epicotyls, respectively) contents and chitinase (4-fold at 2.4 and 4.8 mg/mL in hypocotyls) and β-1,3-D-glucanase (up to about 2-fold at all doses in epicotyls) activities. Micro-Attenuated Total Reflection Fourier Transform Infrared revealed changes in functional groups of primed seeds, hypocotyls and exudates released into the agar because of treatment. Protein extract from PBP-primed seedlings inhibited mycelial growth (67% for epicotyl proteins) and caused morphological alterations in hyphae. This research emphasizes the potential priming role of PBPs applied by seed treatment against soil-borne pathogens.

Using renewable biomass in agriculture, particularly microalgae as a biostimulant, offers economic and environmental sustainability benefits by reducing costs, improving nutrient cycling, and enhancing water use efficiency. Microalgae contain bioactive compounds that boost crop tolerance to environmental stresses, including salinity. Saline soils, characterized by elevated sodium chloride (NaCl) levels, negatively impact many crops, resulting in low productivity and high remediation costs. Therefore, this study evaluates the biostimulant properties of a microalgae-based commercial preparation (MR) on lettuce (Lactuca sativa L.) plants grown hydroponically and exposed to saline stress. The extract was chemically characterized through elemental analysis, lipid composition (gas chromatography with flame ionization detector—GC-FID), the determination of functional groups (Fourier Transformed Infrared—FT-IR), structure (¹H,¹³C Nuclear Magnetic Resonance—NMR), with their hormone-like activity also assessed. Lettuce plants were treated with or without the microalgae blend, in combination with 0, 50 mM, or 100 mM NaCl. The contents of nutrients, soluble proteins, chlorophylls, and phenols, as well as the lipid peroxidation, antioxidants and root traits of lettuce plants, were estimated. The microalgae applied to salt-stressed plants resulted in a significant increase in biomass, protein, and chlorophyll contents. Additionally, significant effects on the secondary metabolism and mitigation of salinity stress were observed in terms of increased phenol content and the activity of antioxidant enzymes, as well as decreased lipid peroxidation. The potassium (K⁺) content was increased significantly in plants treated with 100 mM NaCl after addition of microalgae, while the content of sodium (Na⁺) was concurrently reduced. In conclusion, our results demonstrate that using microalgae can be a potent approach for improving the cultivation of Lactuca sativa L. under saline stress conditions.

Grape production generates substantial agricultural waste, particularly grape pomace, a by-product rich in bioactive compounds. Moreover, its reuse is strongly recommended to prevent environmental issues from improper disposal. This study explores the feasibility of using exhausted grape pomace, alone and in combination with anaerobic digestate, as substrates for Pleurotus mushroom cultivation. Grape pomace is rich in fiber, lipids, sugars, proteins, and phenolic compounds, which makes it a promising substrate for this purpose. Elemental analyses of this substrate revealed high carbon (46%) and nitrogen (2.5%) contents, along with greater levels of macro and microelements (P, Ca, Mg, Fe) compared to conventional substrates. Fourier Transformed Infrared (FTIR) spectroscopy identified aliphatic groups from seed fatty acids and polysaccharide bands, typical of the seedless part of grape pomace. Fatty acid evaluation confirmed the presence of partial glycerides with linoleic acid content exceeding 62%, while phenolic composition analysis highlighted a predominance of bound phenols. These chemical characteristics significantly increased mushroom production, with statistically significant increases in fresh weights observed upon the addition of grape pomace, resulting in variations exceeding 130% in some instances. The mixture with digestate exhibited the most promising results, probably due to improved pH values. FTIR and Surface Enhanced Raman Scattering (SERS) spectra of mushrooms grown on different matrices were similar, but with some differences likely related to substrate composition. In addition, SERS analysis identified ergothioneine, a significant fungal amino acid, which was not detectable in the FTIR spectra. This study highlights grape pomace as an effective and sustainable substrate for mushroom cultivation, offering a viable alternative to conventional growth mediums. The high yield and consistent quality of mushrooms grown on grape pomace, particularly when mixed with anaerobic digestate, demonstrate its potential for commercial mushroom production. The findings support the broader goals of sustainable agriculture by promoting the recycling of agricultural by-products, minimizing waste, and adding economic value. This innovative approach to utilizing grape pomace contributes to improved environmental management and opens new opportunities for enhancing the efficiency and sustainability of mushroom cultivation practices.

In the last decades, the number of studies about the valorization of agricultural by-products has strongly increased due to the growing focus on the circular economy. In this context, mushroom cultivation is raising attention for its nutritional properties and adaptability to different growing conditions. The goal of this project is, therefore, to create a link between two production chains, valorizing the solid anaerobic digestate fraction from the biogas plant as a potential substrate for Pleurotus ostreatus full-scale cultivation. A preliminary in vitro trial shows that the mycelia can colonize at the same rate in both the conventional substrate, which was wheat straw added with sunflower cake and the experimental ones supplemented with corn digestate. The most important and innovative part of the work was full-scale cultivation. Quantitative analyses demonstrate that P. ostreatus is capable of growing on the conventional substrate as well as on the substrate containing 15% of digestate without reducing the mushroom harvest. Even better, digestate seems to stimulate a precocious and more homogeneous production. Chemical and spectroscopic analyses on the fruiting bodies confirm the results; in fact, mushrooms show a comparable structural composition, highlighted with FTIR and SERS spectroscopic evaluations. Moreover, the nutrient content did not change due to the addition of digestate. These promising results demonstrate that anaerobic digestate can become a resource for P. ostreatus cultivation without production losses and maintaining the same qualitative characteristics.

Surface-enhanced Raman scattering (SERS) spectroscopy is a straightforward analytical technique capable of providing detailed information about metabolites in biological samples. The objective of this study was to perform a SERS analysis of ergothioneine (EGT), an amino acid synthesized by microbes and fungi, across a range of pH values (acidic to alkaline) and concentrations (2 × 10⁻⁵ M to 2 × 10⁻⁷ M), to understand the dynamic interactions between EGT and silver (Ag) nanoparticles. Furthermore, SERS was applied in situ on mushroom fruiting bodies to detect the presence of EGT. The SERS spectra revealed that the interaction of EGT with Ag nanoparticles underwent significant alterations at varying pH levels, primarily due to isomerization. These changes were associated with modifications in the aromaticity and ionization of the imidazole ring, driven by both metal adsorption and alkaline conditions. Our results indicated the formation of distinct tautomeric forms of the imidazole group, namely the thione and thiol forms, in aqueous solution and on the Ag surface, respectively. Furthermore, the EGT spectra at different concentrations suggested that ionization occurred at lower concentrations. Notably, the SERS spectra of the mushroom fruiting bodies were dominated by prominent bands attributable to EGT, as corroborated by the comparison with the EGT fungal extract and EGT standard. These findings underscore the utility of SERS spectroscopy as a rapid and effective tool for obtaining comprehensive molecular fingerprints, even directly from complex biological matrices such as mushroom fruiting bodies.