Alberto José López-Jiménez

Mushroom production generates large amounts of by-products, particularly stipes, which can represent up to half of the fruiting body biomass. Due to their similar composition to mushroom caps, these residues represent a promising substrate for the development of value-added foods. In this study, oyster mushroom stipes were used as a substrate for solid-state fermentation (SSF) with a Neurospora crassa strain isolated in Albacete to produce a novel meat analogue inspired by the oncom . Fermentation generated a cohesive matrix bound by hyphae that adopted the shape of the mold and exhibited a meat-like color, although with a softer texture. Nutritional analysis revealed a product with relatively low protein content but a complete amino acid profile, enriched in dietary fiber and containing unsaturated fatty acids. These results demonstrate that SSF with N. crassa provides a strategy to upcycle oyster mushroom by-products into fiber-rich meat analogues with potential applications in sustainable food systems.

Summary: Carotenoids and apocarotenoids are widespread specialized metabolites, yet animals, including sponges, lack the ability to synthesize carotenoids de novo and must obtain them from dietary or microbial sources. The roles of carotenoid cleavage dioxygenases (CCDs) in marine animals remain largely unexplored. A CCD from the marine sponge Suberites domuncula (SdCDO) was evaluated for retinoid formation using a synthetic biology approach involving heterologous expression in Escherichia coli and tomato ( Solanum lycopersicum ), combined with metabolic, ultrastructural, and transcriptomic analyses. Unexpectedly, SdCDO did not produce retinoids. Instead, it cleaved lycopene and β‐carotene to generate crocetin dialdehyde, the direct precursor of crocins. In tomato fruits, SdCDO expression triggered crocin accumulation, particularly in locular tissues, while reducing lycopene, lutein, and β‐carotene levels. It also promoted the accumulation of upstream carotenoid intermediates, such as phytoene, phytofluene, and ζ‐carotene. These metabolic changes resulted in orange fruit pigmentation and enhanced antioxidant capacity, along with altered chromoplast ultrastructure and broad downregulation of endogenous carotenoid biosynthetic genes. Overall, these findings reveal unexpected enzymatic plasticity in a sponge‐derived CCD and demonstrate its ability to redirect plant carotenoid metabolism toward crocin biosynthesis. This work highlights the functional diversity of CCDs across kingdoms and their potential for synthetic biology and crop biofortification.

Fungal infections cause severe crop losses (15–60%) despite the use of antifungal agents, a problem exacerbated by climate change, population growth, and resistance. Regulatory restrictions on compounds like tebuconazole highlight the need for sustainable alternatives. This study evaluates the antifungal efficacy of chitosan nanoparticles loaded with Sideritis serrata extract (NPCH-SID) as an eco-friendly solution. The extract was obtained by freeze-drying and ethanol extraction, while NPCH-SID was synthesized via ionic gelation, achieving optimal size and encapsulation efficiency. In vitro assays revealed broad antifungal activity, with up to 156,140-fold improvement against Aspergillus brasiliensis compared to the free extract. Phytotoxicity tests on wheat seeds showed ~95% germination and enhanced root and shoot growth, confirming the safety and growth-promoting effect of this method. These findings position NPCH-SID as a promising tool for sustainable agriculture. Future work will assess its performance against additional pathogens under greenhouse and field conditions.

Crocin biosynthesis involves a complex network of enzymes with biosynthetic and modifier enzymes, and the manipulation of these pathways holds promise for improving human health through the broad exploitation of these bioactive metabolites. Crocins play a significant role in human nutrition and health, as they exhibit antioxidant and anti-inflammatory activity. Plants that naturally accumulate high levels of crocins are scarce, and the production of crocins is highly limited by the characteristics of the crops and their yield. The CCD2 enzyme, initially identified in saffron, is responsible for converting zeaxanthin into crocetin, which is further modified to crocins by aldehyde dehydrogenases and glucosyltransferase enzymes. Crops like tomato fruits, which naturally contain high levels of carotenoids, offer valuable genetic resources for expanding synthetic biology tools. In an effort to explore CCD2 enzymes with improved activity, two CCD2 alleles from saffron and Crocosmia were introduced into tomato, together with a UGT gene. Furthermore, in order to increase the zeaxanthin pool in the fruit, an RNA interference construct was introduced to limit the conversion of zeaxanthin to violaxanthin. The expression of saffron CCD2, CsCCDD2L, led to the creation of transgenic tomatoes with significantly high crocins levels, reaching concentrations of 4.7 mg/g dry weight. The Crocosmia allele, CroCCD2, also resulted in high crocins levels, reaching a concentration of 2.1 mg/g dry weight. These findings underscore the importance of enzyme variants in synthetic biology, as they enable the development of crops rich in beneficial apocarotenoids.

Agaricus bisporus (white button mushroom), Pleurotus ostreatus (oyster mushroom), and Lentinula edodes (shiitake mushroom) are the most cultivated mushrooms in the Spanish region of Castilla-La Mancha. The increasing production of these mushrooms has created opportunities for sustainable utilization of their by-products such as undersized mushrooms, stalks, and stems. This study evaluated the antioxidant, prebiotic, and antimicrobial properties of aqueous, ethanolic and alkaline extracts derived from these by-products. Aqueous extracts from oyster mushroom, rich in glucose-polysaccharides (59.4±0.4% mushroom dw), promoted the growth and lactic acid production of the probiotic bacteria Lactocaseibacillus casei and Lactoplantibacillus plantarum . Shiitake extracts demonstrated antimicrobial activity against Pseudomonas aeruginosa , Escherichia coli and Salmonella enterica (Minimal inhibitory concentrations: 15, 7.5 and 7.5 mg/mL, respectively), and stimulated the growth of lactic acid bacteria at low concentrations (1.875 mg/mL) but inhibiting them at higher concentrations. Extracts from white button mushrooms exhibited the strongest antioxidant activity, particularly ethanolic extracts rich in phenolic compounds (0.015 mg Gallic acid/mg extract). These results highlight the potential of extracts of mushroom by-products as organic sources of antioxidants, antimicrobials, and prebiotics, creating new avenues for food product development. Reusing these by-products could encourage sustainability and assist the mushroom sector in implementing zero-waste and circular economy methods.

Plant exosomes exhibit high stability and easy absorption, and have emerged as promising bioactive tools due to their potential health benefits and biomedical applications. Saffron tepals contain abundant metabolites with potential therapeutic properties and were used for exosome extraction by ultracentrifugation and gradient purification. The exosomes showed an average particle size of 151.5 ± 79.6 nm and exhibited a spherical morphology. Five well-conserved miRNAs—miR157, miR166, miR168, miR396, and miR398—were identified in the exosomes, which are involved in the coordination of growth and physiological plant responses with endogenous and environmental abiotic and biotic signals, and their potential targets in mammals are upregulated in specific cancer types and associated with inflammation. Proteome analysis revealed an enrichment of proteasome proteins, ribosomal proteins, and proteins involved in the cytoskeleton, transport across the membrane (ABC transporters), and vesicle trafficking (RAB GTPases, TM9SF and Coatomer subunits). Metabolite analyses showed mainly anthocyanins. The exosomes have selective stimulatory activity on macrophages, increasing the expression of surface molecules (CD80 and CD86), and cytokines (IL-1β, IL-6, and TNF-α), but not the levels of IL-10. Overall, these results indicated that saffron flowers are an effective and abundant source of exosomes as new nanomedicines for human health.

Agaricus bisporus (white button mushroom), Pleurotus ostreatus (oyster mushroom), and Lentinula edodes (shiitake mushroom) are the most cultivated mushrooms in the Spanish region of Castilla‐La Mancha. The increasing production of these mushrooms has created opportunities for sustainable utilization of their by‐products such as undersized mushrooms, stalks, and stems. This study evaluated the antioxidant, prebiotic, and antimicrobial properties of aqueous, ethanolic, and alkaline extracts derived from these by‐products. Aqueous extracts from oyster mushroom, rich in glucose‐polysaccharides (59.4 ± 0.4% mushroom dw), promoted the growth and lactic acid production of the probiotic bacteria Lactocaseibacillus casei and Lactoplantibacillus plantarum . Shiitake extracts demonstrated antimicrobial activity against Pseudomonas aeruginosa , Escherichia coli, and Salmonella enterica (minimal inhibitory concentrations: 15, 7.5, and 7.5 mg/mL, respectively) and stimulated the growth of lactic acid bacteria at low concentrations (1.875 mg/mL) but inhibiting them at higher concentrations. Extracts from white button mushrooms exhibited the strongest antioxidant activity, particularly ethanolic extracts rich in phenolic compounds (0.015 mg gallic acid/mg extract). These results highlight the potential of extracts of mushroom by‐products as organic sources of antioxidants, antimicrobials, and prebiotics, creating new avenues for food product development. Reusing these by‐products could encourage sustainability and assist the mushroom sector in implementing zero‐waste and circular economy methods.

Current crop management worldwide is shifting toward the use of environmentally friendly products. With this objective, we developed a new phytosanitary product with biostimulant properties based on the encapsulation of garlic extract at a lower dose (<0.1%) in chitosan nanoparticles as a seed nano-priming agent. In the present study, the morphology of the nanoparticles, their stability under prolonged storage conditions, and their efficacy as a biostimulant are evaluated on cereals in rainfed crops, and the activities were correlated with a transcriptomic analysis. The nanoparticles showed a spherical shape and had a maximum size close to 200 nm with satisfactory stability at 4 °C, reducing the probability of aggregation processes in the nanoparticles. The biostimulant properties of the nano-priming agent were evaluated in a field experiment with wheat, barley, and oat seeds at 30 and 90 days, showing that plants treated with nanoparticles showed significant differences with higher values in root development, leaf length, and total plant weight. Finally, through a RNA-SEQ analysis of the treated wheat seeds, we have confirmed that the nano-treatment showed a higher increases in regard to development, metabolism, and plant response genes compared with untreated seeds.

Saffron (Crocus sativus L.), a historically significant crop valued for its nutraceutical properties, has been poorly explored from a phytosanitary perspective. This study conducted a thorough examination of viruses affecting saffron samples from Spanish cultivars, using high-throughput sequencing alongside a systematic survey of transcriptomic datasets from Crocus sativus at the Sequence Read Archive. Our analysis unveiled a broad diversity and abundance, identifying 17 viruses across the 45 analyzed libraries, some of which were highly prevalent. This includes known saffron-infecting viruses and previously unreported ones. In addition, we discovered novel viruses from the Alphaflexiviridae, Betaflexiviridae, Potyviridae, Solemoviridae, and Geminiviridae families, with some present in libraries from various locations. These findings indicate that the saffron-associated virome is more complex than previously reported, emphasizing the potential of phytosanitary analysis to enhance saffron productivity.