Seed-Borne Probiotic Yeasts Foster Plant Growth and Elicit Health Protection in Black Gram (Vigna mungo L.)

Microbial community assembly and chemical dynamics of raw brewers' spent grain during inoculated and spontaneous solid-state fermentation

Solid-state fermentation (SSF) carried out by microbial bioinoculants is an environmentally friendly technology for the sustainable recovery and valorization of agri-food wastes. Particularly, mesophilic SSF processes allows the production of bio-organic fertilizers enriched with beneficial soil microorganisms. However, the establishment of microbial consortia and the interaction with native waste microbiota still require thoughtful investigations. Here, raw brewers' spent grain (BSG), the main waste from the brewing industry, was subjected to two mesophilic SSF processes (maximum temperature of 35 °C) carried out by a multi-kingdom microbial bioinoculant and the BSG spontaneous microbiota. After 90 days, both SSF processes led to stable organic soil amendments, as indicated by the C:N ratio (10.00 ± 1.4), pH (6.66 ± 0.09), and DOC (8.45 ± 1.2 mg/g) values. Additionally, the fermented BSG showed a high nitrogen content (42.2 ± 3.4 mg/Kg) and biostimulating activities towardLepidium sativumseeds. The monitoring of microbial communities by high-throughput sequencing of 16S and ITS rRNA indicated that BSG samples were enriched in microbial genera with interesting agronomic applications (i.e.,Devosia, Paenibacillum, Trichoderma, Mucor, etc.). Microbial cross-kingdom network analyses suggested that the microbial assembly of BSG was significantly influenced by the bioinoculant, despite the inoculated microbial genera being able to persist in BSG samples only the first week of SSF. This suggests that the study of microbial interactions between exogenous microbial inoculants and waste resident microbiota is required to optimize SSF processes aimed at the recovery and valorization of unprocessed wastes.

The Biosynthesis, Accumulation of Phenolic Compounds and Antioxidant Response in Lactuca sativa L. Plants Inoculated with a Biofertilizer Based on Soil Yeast and Iron Nanoparticles

Lettuce is a vegetable that contributes vitamins, minerals, fibre, phenolic compounds and antioxidants to the human diet. In the search for improving production conditions and crop health, the use of microorganisms with plant growth-promoting capabilities, such as soil yeasts (PGPY), in conjunction with nanotechnology could offer sustainable development of agroecosystems. This study evaluated the synthesis of health-promoting bioactive compounds in lettuce under the application of soil yeast and an iron nanoparticle (NP-Fe2O3) encapsulated in alginate beads. Two yeast strains, Candida guillermondii and Rhodotorula mucilaginosa, and a consortium of both yeasts were used in the presence and absence of Fe2O3-NPs. Phenolic compounds were identified and quantified via HPLC-ESI-Q-ToF and antioxidant activity. Ten phenolic compounds were identified, highlighting the chicoric acid isomer and two quercetin glycosides with high concentrations of up to 100 µg g-1 in treatments with C. guillermondii. Treatments with R. mucilaginosa and NPs-Fe2O3 presented an increase in antioxidant activity, mainly in TEAC, CUPRAC and DPPH activities in leaves, with significant differences between treatments. Therefore, the use of encapsulated soil yeasts is a viable alternative for application in vegetables to improve the biosynthesis and accumulation of phenolic compounds in lettuce and other crops.

Biochemical and Biotechnological Insights into Fungus-Plant Interactions for Enhanced Sustainable Agricultural and Industrial Processes

The literature is full of studies reporting environmental and health issues related to using traditional pesticides in food production and storage. Fortunately, alternatives have arisen in the last few decades, showing that organic agriculture is possible and economically feasible. And in this scenario, fungi may be helpful. In the natural environment, when associated with plants, these microorganisms offer plant-growth-promoting molecules, facilitate plant nutrient uptake, and antagonize phytopathogens. It is true that fungi can also be phytopathogenic, but even they can benefit agriculture in some way-since pathogenicity is species-specific, these fungi are shown to be useful against weeds (as bioherbicides). Finally, plant-associated yeasts and molds are natural biofactories, and the metabolites they produce while dwelling in leaves, flowers, roots, or the rhizosphere have the potential to be employed in different industrial activities. By addressing all these subjects, this manuscript comprehensively reviews the biotechnological uses of plant-associated fungi and, in addition, aims to sensitize academics, researchers, and investors to new alternatives for healthier and more environmentally friendly production processes.

Efficacy of biological agents and fillers seed coating in improving drought stress in anise

Many plants, including anise, have tiny, non-uniform seeds with low and light nutrient reserves. The seeds also show a weak establishment, especially under stressful conditions where their accurate planting in the soil and optimal yield are tough. This study sought to improve anise seeds' physical and physiological characteristics under drought stress. To this end, two factorial experiments under laboratory and greenhouse conditions were performed in a completely randomized design with 4 and 3 replications, respectively. Five levels of seed inoculation (inoculation with T36 and T43 of Trichoderma harzianum, and CHA0 and B52 of Pseudomonas fluorescent, and non-inoculation which means that control seeds were not treated with microbial inoculant), three levels of coating (K10P20, K10P10V5, and non-coating), and three levels of drought stress (0, -3, and -6 bars) were considered as the factorial experiment [vermiculite (V), kaolin (K), and perlite (P) numbers refer to the amount of material used in grams]. The laboratory experiment revealed that the combined treatments of bio-agents with coating increased the physical and germination characteristics of anise seeds compared to the control treatment. The greenhouse experiment showed that drought stress reduced the initial growth indices. Still, the combination treatments of biological agents and coating (fillers) could alleviate the destructive effects of drought stress to some extent and improve these indices. The best treatment was provided by T36 and K10P20 in both experiments, which significantly increased morphological indices.