RESUMEN
Lignocellulosic biomass is a significant source of sustainable fuel and high-value chemical production. However, due to the complex cross-linked three-dimensional network structure, lignin is highly rigid to degradation. In natural environments, the degradation is performed by wood-rotting fungi. The process is slow, and thus, the use of lignin degradation by fungi has not been regarded as a feasible technology in the industrial lignocellulose treatment. Fungi produce a wide variety of ligninolytic enzymes that can be directly introduced in industrial processing of lignocellulose. Within this study, screening of ligninolytic enzyme production using decolorization of ABTS and Azure B dyes was performed for 10 fungal strains with potentially high enzyme production abilities. In addition to standard screening methods, media containing lignin and hay biomass as carbon sources were used to determine the change in enzyme production depending on the substrate. All selected fungi demonstrated the ability to adapt to a carbon source limitation; however, four strains indicated the ability to secrete ligninolytic enzymes in all experimental conditions-Irpex lacteus, Pleurotus dryinus, Bjerkandera adusta, and Trametes versicolor-respectively displayed a 100%, 82.7%, 82.7%, and 55% oxidation of ABTS on lignin-containing media and 100%, 87.9%, 78%, and 70% oxidation of ABTS on hay-containing media after 168 h of incubation. As a result, the most potent strains of fungi were selected to produce lignocellulose-degrading enzymes and to demonstrate their potential application in biological lignocellulose pretreatment.
RESUMEN
Tertiary wastewater treatment with microalgae incorporates environmental sustainability with future technologies and high exploitation costs. Despite the apparent ecological benefits of microalgae-assisted wastewater treatment/biomass-based resource production, technological improvements are still essential to compete with other technologies. Bio-flocculation instead of mechanical harvesting has been demonstrated as an alternative cost-effective approach. So far, mostly filamentous fungi of genus Aspergillus have been used for this purpose. Within this study, we demonstrate a novel approach of using white-rot fungi, with especially high potential of algae-Irpex lacteus complex that demonstrates efficiency with various microalgae species at a broad range of temperatures (5-20 °C) and various pH levels. Harvesting of microalgae from primary and secondary wastewater resulted in 73-93% removal efficiencies within the first 24 h and up to 95% after 48 h. The apparent reuse potential of the algae-I. lacteus pellets further complements the reduced operating costs and environmental sustainability of bio-flocculation technology.
RESUMEN
Lignocellulosic biomass can be used as a source for energy, fuel and valuable chemical production. From all available technologies, biological approaches have been recognized as the most environmentally friendly and sustainable ones. At the same time, high conversion costs, low efficiency and environmental issues still hinder the introduction of biological processes into industrial scale manufacturing. The aim of this study was to determine the most suitable enzyme cocktail recovery conditions from a biomass-fungal culture of the white-rot basidiomycete Irpex lacteus. Subsequent evaluation of the overall enzyme cocktail efficiency to release fermentable carbohydrates from biomass showed that prolonged fungal cultivation decreases the quality of the produced enzyme cocktail. At the same time, introduction of ultrasound pre-treatment during enzyme extraction improved the recovered enzyme cocktail efficiency in converting biomass to fermentable sugars, yielding up to 0.25 g of fermentable sugar per g dry hay biomass and up to 0.11 g per g dried straw or microalgae substrates. The results demonstrated that the production of lignocellulose-degrading enzymes from fungi is more sensitive than previously described, especially in terms of fungal growth, culture sterility and incubation conditions.