Microalgae are photoautotrophic microorganisms capable of producing compounds with potential bioenergetic applications as an alternative energy source due to the imminent exhaustion of fossil fuels, their impact on the environment, and the constant population increase. The mass cultivation of these microorganisms requires high concentrations of nutrients, which is not profitable if analytical grade culture media are used. A viable alternative is the use of agro-industrial wastewater, due to the metabolic flexibility of these microorganisms and their ability to take advantage of the nutrients present in these substrates. For the reasons mentioned above, the effect of the cultivation in wastewater from cheese processing on the growth parameters and biomass composition of Scenedesmus sp. was evaluated, and its nutrient removal capacity determined. A high lipid concentration was obtained in the cultures with the dairy effluent (507.81 ± 19.09 mg g⁻¹) compared to the standard culture medium, while the growth parameters remained similar to the control medium. Scenedesmus sp. achieved high percentages of nutrient assimilation of the wastewater used (88.41% and 97.07% for nitrogen and phosphorus, respectively). With the results obtained, the feasibility of cultivating microalgae in agro-industrial wastewater as an alternative culture medium that induces the accumulation of compounds with potential bioenergetic applications was verified.

The unique perspective that microalgae biomass presents for bioenergy production is currently being strongly considered. This type of biomass production involves large amounts of nutrients, due to nitrogen and phosphorous fertilizers, which impose production limitations. A viable alternative to fertilizers is wastewater, rich in essential nutrients (carbon, nitrogen, phosphorus, potassium). Therefore, Arthrospira platensis was cultivated in 150 mL photobioreactors with 70% (v/v) with the wastewater from a dairy industry, under a regime of light:dark cycles (12 h:12 h), with an irradiance of 140 μmol m−2 s−1 photon. The discontinuous cultures were inoculated with an average concentration of chlorophyll-a of 13.19 ± 0.19 mg L−1. High biomass productivity was achieved in the cultures with wastewater from the dairy industry (1.1 ± 0.02 g L−1 d−1). This biomass was subjected to thermal and physical treatments, to be used in co-digestion with cattle manure. Co-digestion was carried out in a mesophilic regime (35 °C) with a C: N ratio of 19:1, reaching a high methane yield of 482.54 ± 8.27 mL of CH4 g−1 volatile solids (VS), compared with control (cattle manure). The results demonstrate the effectiveness of the use of cyanobacterial biomass grown in wastewater to obtain bioenergy.

Transforming traditional linear production into sustainable circular processes is crucial, and integrating microalgae biomass production with wastewater recycling is a promising approach. This study addresses key challenges using dairy industry effluents as a nutrient-rich medium, achieving high biomass productivity and protein content with Scenedesmus sp. grown in an 80% wastewater-based medium. Impressive nutrient removal efficiencies were recorded for TN (79.24%) and PO₄^-3 (77.14%). The proposed culture medium achieved maximum productivity of 0.22 ± 0.05 g L⁻¹ day⁻¹ and a high protein concentration of 384.38 ± 34.06 mg g⁻¹, demonstrating the medium’s efficiency in promoting substantial biomass and nutritional quality. The application of Scenedesmus sp. biomass in treatment T₁ (extract) and T₂ (culture) in Phaseolus vulgaris significantly improved soil quality, increasing the concentration of organic matter (SOM), nitrates, phosphates, and microbial activity. Additionally, T₁ promoted the vegetative and reproductive development of P. vulgaris, as reflected in a germination index of 305.81%, an average height of 49.52 cm, higher leaf density, a greater number of floral buds, and enhanced floral development. These results demonstrate the bio-stimulatory potential of biomass and its role in practical bioremediation, highlighting the environmental and agricultural benefits of this innovative approach.

Anaerobic digestion is a method of agricultural residue transformation used in bioenergy, making these activities energy efficient. However, it can be limited on a larger scale by the availability and diversity of organic residues related to carbon-nitrogen (C/N). Therefore, the anaerobic co-digestion of bovine manure and Jatropha seed cake (Jatropha curcas) were evaluated, with three different C/N ratios, under two conditions: mesophilic (30ºC) and thermophilic (50ºC). Biodigesters were mounted with three replicates for each C/N ratio. The highest production of CH4 was registered after 30 days of processing in the thermophilic condition (C/N 25:1) with 633.95 ± 5.59 mL of CH4 g-1 VS. In contrast, the lowest production was in the mesophilic condition (C/N 20:1) with 208.66 ± 2.61 mL of CH4 g-1 VS. The feasibility of co-digestion of agricultural residues in the production of CH4 as a possible bioenergetic alternative demonstrated.

Mangrove ecosystems are biodiversity hotspots and vital carbon sinks, yet their fungal communities—key drivers of nutrient cycling and ecosystem resilience—remain largely unexplored in the Neotropics. This is particularly true for Ecuador's protected reserves, where no molecular census of sediment fungi exists. To address this gap, we conducted the first metabarcoding survey of the fungal microbiome in the sediments of the Reserva Ecológica Manglares Churute (REMC), a critical mangrove habitat under increasing anthropogenic pressure. This is the first molecular study to characterize fungal communities in the mangrove sediments of the Reserva Ecológica Manglares Churute (REMC) in the neotropical context of Ecuador, using metabarcoding. The fungal community was dominated by Ascomycota (68%) and Basidiomycota (30%), with minor contributions from Mortierellomycota, Chytridiomycota, and Mucoromycota (<0.1%), and 2.10% unclassified at the phylum level. The most diverse sample (2005L2-69) had a Shannon index of 2.166. Rarefaction curves indicated that additional sampling could reveal more fungal diversity. Fungal assemblages were similar across samples, with minor variations linked to environmental factors. Predominant classes included Dothideomycetes, Agaricomycetes, and Eurotiomycetes. At the genus level, Ascochyta (27%), Antrodia (24%), and Talaromyces (17%) were the most abundant. The presence of genera such as Talaromyces and Penicillium highlights their biotechnological potential, like antibacterial properties. At the same time, the abundance of Ascochyta , a phytopathogen, suggests potential stress or disease susceptibility in this area of REMC. This research provides an essential preliminary overview of the mycobiome in this underexplored region and identifies principal taxa of ecological and biotechnological importance. Furthermore, this investigation, conducted in a specific area of REMC sediments, employs metabarcoding analysis utilizing ITS86-ITS4 primers in Neotropical mangroves, thereby contributing to the global understanding of mangrove microbiomes.

The escalating global demand for water resources, combined with anthropogenic pollution, poses a significant threat to the availability of potable water. Even small-scale pig farms generate enough wastewater to pose environmental risks. Microalgal wastewater treatment offers an effective solution for pollutant recycling, providing advantages such as reduced energy consumption, lower greenhouse gas emissions, and greater cost efficiency compared to conventional methods. The biomass produced through this process has multiple valuable applications, including use as a biostimulant and biofertilizer. Consequently, this study investigates the use of the microalga Limnospira platensis for the biological treatment of undiluted pig slurry, intending to develop a sustainable biostimulant. Initially, a molecular characterization of the Limnospira platensis strain was performed to verify its identity. The research employed 150 mL bubble column photobioreactors (BCPs) with a continuous airflow of 15 mL min ^-1 , followed by the application of the resulting biomass as a biostimulant for Cucumis sativus . The productivity of Limnospira platensis was monitored daily in cultures grown in pig slurry. The results demonstrated that Limnospira platensis effectively treated pig slurry, producing biomass at a concentration of 1.34 g L ^-1 , and a productivity of 0.88 g L ^-1 day ^-1 . The highest removal efficiencies recorded were 99.93% for Chemical Oxygen Demand (COD), 94.83% for total phosphorus (TP), 98.93% for total nitrogen (TN), and 100% for NH ₄ ⁺ and total coliforms. The most favorable biostimulant effect of Limnospira platensis biomass on C. sativus was observed in T ₂ (0.5 g L ^-1 with centrifugation and cellular disruption), which yielded a germination index of 515.34% ± 81.81%, a shoot number of 2.20 ± 0.04, and a root number of 10.33 ± 0.17. These findings demonstrate the feasibility of using microalgae to treat wastewater with high organic loads, highlighting the significant biostimulatory potential of the biomass produced in these treatment systems.