Marco Zannotti

The olive oil industry generates substantial by-products, notably olive pomace and stones, which present environmental challenges yet harbour untapped bioactive potential. This study investigated the phenolic profiles, antioxidant capacity, and probiotic growth-promoting and antimicrobial activities of olive pomace (OP), olive pomace extract (OPE), olive stones (OS), and olive stone extract (OSE). Phenolic composition, determined by HPLC-DAD/MS, revealed a richer profile and higher phenolic levels in OPE than in OSE, consistent with antioxidant capacity, which was 56.8% higher in OPE (as Trolox equivalents). Probiotic growth promotion was assessed using Lactiplantibacillus plantarum IMC 509 and Lacticaseibacillus rhamnosus IMC 501^®, monitoring growth curves, short-chain fatty acid (SCFA) production, total phenolic content (TPC), and antioxidant levels in supplemented culture fluids. Antimicrobial activity was examined against opportunistic pathogens such as Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus. All substrates supported probiotic proliferation, and fermenting fluids from L. plantarum IMC 509 increased or sustained SCFA production after 28–30 h. OP and OPE significantly enhanced TPC and antioxidant capacity for both strains, whilst OPE and OSE inhibited the tested pathogens. These findings identify olive oil by-products as promising functional food and nutraceutical ingredients, providing preliminary in vitro evidence whilst offering a route to valorise a problematic waste stream.

Nannochloropsis spp. are versatile microalgae known for their ability to treat wastewater while generating value-added products. In this study, Nannochloropsis oceanica biomass was combined with two organic waste streams, spent coffee grounds (SCG) and brewer’s spent grain (BSG) to produce two fertilizers: a microalgae-based fertilizer with SCG (MSF), and one with BSG (MBF). Both fertilizers were optimized and exhibited reduced salinity, attributable to the use of marine microalgal biomass. The C/N ratio fell within a favorable range, flowability improved compared to the raw materials, and both formulations significantly increased soil water-holding capacity relative to the unfertilised control. MSF showed higher antioxidant activity (1246.53±1.32 mg TE/kg), while MBF had the highest total phenolic content (3325.32±12.30 mg GAE/kg) after SCG (6844.50±162.28 mg GAE/kg); however, total flavonoid content was reduced in both fertilizers compared to the starting raw materials. Phytotoxicity tests using Lepidium sativum, Sinapis alba, and Sorghum saccharatum showed positive effects on seed germination and root elongation. This was also supported by the Munoo-Liisa Vitality Index, which exceeded 80% in all cases, except for the 15% MBF treatment, indicating predominantly biostimulatory effects under the tested conditions. Life cycle assessment indicated that MSF reduced environmental impacts by up to 79% compared to MBF across all categories. Overall, these findings demonstrate that the novel microalgae-based fertilizer formulations possess physicochemical properties that enhance soil health and early plant development and represent a promising circular fertilization strategy that promotes nutrient circularity, waste valorization and agricultural sustainability.

The olive oil industry, a cornerstone of Mediterranean agricultural economies, generates substantial by-products such as olive pomace and stones, posing environmental challenges while harboring untapped bioactive potential. This study investigates antioxidant, prebiotic and antimicrobial activities of such by-products and their hydroalcoholic extracts: olive pomace (OP), olive pomace extract (OPE), olive stones (OS), and olive stone extract (OSE). Phenolic composition, assessed by HPLC-DAD/MS, revealed a richer profile and higher levels of phenolics in OPE than in OSE, in agreement with their antioxidant levels, which resulted 56.8% higher in OPE (as Trolox equivalents). Prebiotic activities were investigated with probiotic strains of Lactiplantibacillus plantarum IMC 509® and Lacticaseibacillus rhamnosus IMC 501®, monitoring the growth curves, short-chain fatty acids (SCFAs) production, total phenol content (TPC), and antioxidant levels in the culture fluids supplemented with OP, OPE, OS, OSE. Antimicrobial activities against common gut pathogens, i.e. Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus, were also explored. All substrates supplied favorable conditions for probiotic proliferation. Fermenting fluids from L. plantarum IMC 509® cultured in presence of OP, OPE, OS, and OSE increased significantly SCFAs production, compared to control sample, after 28 hours of fermentation. Fluids supplemented with OP and OPE significantly increased TPC and antioxidant capacity at the end of fermentation for both probiotic strains. Both OPE and OSE revealed inhibitory effects on the investigated pathogens. These findings position olive by-products as valuable resources for sustainable production of functional foods, nutraceuticals, and pharmaceuticals, offering a compelling solution to environmental concerns while unlocking health benefits.

Squalene and squalane are widely used cosmetic ingredients valued for their emollient properties and excellent skin compatibility, yet sustainable sourcing remains a challenge. This study presents an integrated and eco-friendly strategy for valorizing wine lees as a renewable source of squalene and converting it into stable, high-performance squalane. Squalene was efficiently recovered from yeast-rich winery waste through optimized ultrasound-assisted extraction, followed by chromatographic purification. Green catalytic hydrogenation using palladium supported on natural clay minerals enabled the selective conversion of squalene into squalane under mild conditions. The functional evaluation via in vitro transport studies across an artificial membrane, using quercetin as a poorly permeable model antioxidant, demonstrated enhanced permeation compared with conventional vehicles, while accelerated aging experiments further confirmed the superior oxidative stability of squalane relative to native squalene. Overall, this work provides a proof of concept for upcycling winery by-products into multifunctional cosmetic ingredients that combine sustainability, stability, and functional performance, supporting circular economy principles and the growing demand for ethically sourced raw materials in the cosmetic industry.

Antarctic microorganisms have developed extraordinary strategies for adaptation. They have also demonstrated the ability to produce various biopolymers in response to environmental stress. The demand for biopolymers is constantly increasing and is expected to grow further. Among emerging biomaterials, bacterial cellulose (BC) is generating significant interest due to its unique characteristics that distinguish it from plant-based cellulose. BC exhibits higher purity, water-holding capacity, and tensile strength compared to its plant-based counterpart. Furthermore, BC can be obtained through environmentally friendly protocols. Several bacterial strains have already been identified as cellulose producers, including Komagataeibacter xylinus. In this study, a marine bacterial strain named Pseudomonas sp. ef1, isolated from a consortium associated with the Antarctic ciliate Euplotes focardii, was tested for cellulose production. We found that this Antarctic Pseudomonas can produce BC in conditions that appear unique to this bacterial strain. Furthermore, the final BC product is structurally different from that obtained from the well-known BC producer Komagataeibacter xylinus. Additionally, a putative cellulose synthase was identified from the Pseudomonas sp. ef1 genome, exhibiting unique characteristics that may account for the unique BC production capability of this Antarctic marine Pseudomonas. The versatility of BC opens numerous applications, including in papermaking, food, pharmaceutical, and biomedical sectors.

Due to the rising atmospheric carbon dioxide levels driven by human activity, extensive scientific efforts have been dedicated to developing methods aimed at reducing its concentration in the atmosphere. A novel approach involves using hydrates as a long-lasting reservoir of CO₂ sequestration. This review provides an initial overview of hydrate characteristics, their formation mechanisms, and the experimental techniques commonly employed for their characterization, including X-ray, Raman spectroscopy, cryoSEM, DSC, and molecular dynamic simulation. One of the main challenges in CO₂ sequestration via hydrates is the requirement of high pressures and low temperatures to stabilize CO₂ molecules within the hydrate crystalline cavities. However, deviations from classical temperature-pressure phase diagrams observed in natural and engineered environments can be explained by considering that hydrate stability and formation are primarily governed by chemical potentials, not just temperature and pressure. Activity, which reflects concentration and non-ideal interactions, greatly influences chemical potentials, emphasizing the importance of solution composition, salinity, and additives. In this context the role of promoters and inhibitors in facilitating or hindering hydrate formation is discussed. Furthermore, the review presents an overview of the impact of marine sediments and naturally occurring compounds on CO₂ hydrate formation, along with the sampling methodologies used in sediments to determine the composition of these natural compounds. Special attention is given to the effect and chemical characterization of dissolved organic matter (DOM) in marine aquatic environments. The focus is placed on the key roles of various natural occurring molecules, such as amino acids, protein derivatives, and humic substances, along with the analytical techniques employed for their chemical characterization, highlighting their central importance in the CO₂ gas hydrates formation.

Antarctic microorganisms have developed extraordinary strategies for adaptation. They have also demonstrated the ability to produce various biopolymers in response to environmental stress. The demand for biopolymers is constantly increasing and is expected to grow further. Among the emerging biomaterials, bacterial cellulose (BC) is generating significant interest due to its unique characteristics that distinguish it from plant-based cellulose. BC exhibits higher purity, water-holding capacity, and tensile strength compared to its plant-based counterpart. Furthermore, BC can be obtained through environmentally friendly protocols. Several bacterial strains have already been identified as cellulose producers, including Komagataeibacter xylinus. In this study, a marine bacterial strain named Pseudomonas sp. ef1, isolated from a consortium associated with the Antarctic ciliate Euplotes focardii was tested for cellulose production. We found that this Antarctic Pseudomonas can produce BC in conditions that appear unique to this bacterial strain. Furthermore, the final BC product is structurally different from that obtained from the well-known BC producer Komagataeibacter xylinus. Additionally, a putative cellulose synthase was identified from the Pseudomonas sp. ef1 genome, exhibiting unique characteristics that may account for the unique BC production capability of this Antarctic marine Pseudomonas. The versatility of BC opens numerous applications, including in papermaking, food, pharmaceutical, and biomedical sectors.

Three types of solid waste are produced during beer fermentation: spent grain, hot trub, and residual yeast. While the first is used as livestock feed, the seconds has not yet found any real reapplication in the field of circular economy. The aim of this work is to study and characterize these two brewing wastes, i.e., hot trub and residual yeast, to evaluate their potential reuse in the agricultural field. Samples from top-fermented and bottom-fermented beers were chemically investigated. Initially, the safety was assessed via multi-detection analysis of 57 mycotoxins, and all samples were deemed safe. Subsequently, the chemical and elemental composition was examined via ICP-MS and microanalysis, along with phenolic compounds and antioxidant activity via HPLC and spectrophotometric determinations, to achieve a thorough characterization of these waste samples. The C/N ratio of residual yeast from top-fermented beer and hot trub of the bottom-fermented one were near the optimal one (10:1). This research marks an initial step towards repurposing brewery waste materials as fertilizers. The subsequent steps will involve the formulation and field trials.

Acmella oleracea (L.) R.K. Jansen, also called jambù, is a medicinal and aromatic plant native to the Brazilian Amazon rainforest and phytochemically characterized by N-alkylamides with spilanthol as the main active compound. Jambù recently attracted the interest of many companies because of its wide range of pharmaceutical, nutraceutical, and cosmetic applications. In this context, it is desirable to identify eco-friendly cultivation methods that not only minimize the environmental footprint but also support the biosynthesis of the plant’s valuable bioactive compounds. The zero-discharge approach of aquaponics makes this growing system an eco-friendly and sustainable production strategy for crops. Thus, a greenhouse experiment was conducted on two jambù cultivars, i.e., cv ‘purple’ and cv ‘yellow’, grown in aquaponic and hydroponic systems. The objective was to compare their contents of N-alkylamides, their numbers of capitula, which are the main source of these bioactives, and their volatile profiles. The results highlighted differences between the two cultivars and among plants harvested at different periods. Interestingly, aquaponics yielded plants with a high N-alkylamide content, which was comparable to that obtained with hydroponics. Overall, this study highlighted the feasibility of adopting aquaponics to grow A. oleracea, paving the way for circular economy-based and sustainable agricultural practices.