RESUMEN
Microalgae growth-promoting bacteria (MGPB), both actinobacteria and non-actinobacteria, have received considerable attention recently because of their potential to develop microalgae-bacteria co-culture strategies for improved efficiency and sustainability of the water-energy-environment nexus. Owing to their diverse metabolic pathways and ability to adapt to diverse conditions, microalgal-MGPB co-cultures could be promising biological systems under uncertain environmental and nutrient conditions. This review proposes the recent updates and progress on MGPB for microalgae cultivation through co-culture strategies. Firstly, potential MGPB strains for microalgae cultivation are introduced. Following, microalgal-MGPB interaction mechanisms and applications of their co-cultures for biomass production and wastewater treatment are reviewed. Moreover, state-of-the-art studies on synthetic biology and metabolic network analysis, along with the challenges and prospects of opting these approaches for microalgal-MGPB co-cultures are presented. It is anticipated that these strategies may significantly improve the sustainability of microalgal-MGPB co-cultures for wastewater treatment, biomass valorization, and bioproducts synthesis in a circular bioeconomy paradigm.
Asunto(s)
Bacterias , Biomasa , Técnicas de Cocultivo , Microalgas , Aguas Residuales , Microalgas/metabolismo , Microalgas/crecimiento & desarrollo , Aguas Residuales/microbiología , Bacterias/metabolismo , Bacterias/crecimiento & desarrollo , Purificación del Agua/métodos , Redes y Vías Metabólicas , Biología Sintética/métodos , Actinobacteria/metabolismo , Actinobacteria/crecimiento & desarrolloRESUMEN
Microalgae are promising organisms that are rapidly gaining much attention due to their numerous advantages and applications, especially in biorefineries for various bioenergy and biochemicals. This review focuses on the microalgae contributions to Bio-Circular-Green (BCG) economy, in which zero-waste approaches for sustainable production and biorefineries of microalgal biomass are introduced and their possible integration is discussed. Firstly, overviews of wastewater upcycling and greenhouse gas capture by microalgae are given. Then, a variety of valuable products from microalgal biomass, e.g., pigments, vitamins, proteins/peptides, carbohydrates, lipids, polyunsaturated fatty acids, and exopolysaccharides, are summarized to emphasize their biorefinery potential. Techno-economic and environmental analyses have been used to evaluate sustainability of microalgal biomass production systems. Finally, key issues, future perspectives, and challenges for zero-waste microalgal biorefineries, e.g., cost-effective techniques and innovative integrations with other viable processes, are discussed. These strategies not only make microalgae-based industries commercially feasible and sustainable but also reduce environmental impacts.
Asunto(s)
Microalgas , Microalgas/química , Biomasa , Conservación de los Recursos Energéticos , Biocombustibles , Aguas ResidualesRESUMEN
Oleaginous microalga Scenedesmus sp. SPP was rapidly immobilized in oleaginous fungal pellets by their opposite-surface-charges. Microalgae-fungal (MF) pellets were more effective in bioremediation of non-sterile secondary effluent than mono-culture. The optimal hydraulic retention time for dual bioremediation in semi-continuous mode was 72 h. The MF pellets coated with 0.4 %-chitosan improved removal efficiencies of COD, total nitrogen (TN), and total phosphorus (TP) up to 96.2±0.0 %, 88.2±2.8 % and 71.5±0.7 %, respectively, likely because of better cell retention and more nutrient adsorption and assimilation. Dual bioremediation by coated MF pellets was also successfully scaled up in 30-L bubble-column photobioreactors with improved COD, TN, and TP removal efficiencies of 98.5±0.0 %, 90.2±0.0 % and 79.5±2.1 %, respectively. This system also effectively removed CO2 from simulated flue gas at 71.2±0.4 % and produced biomass with high lipid content. These results highlight the effectiveness of bio-immobilization by fungal pellets; chitosan coating; and their practical applications in bioremediation and CO2 sequestration.
Asunto(s)
Quitosano , Microalgas , Dióxido de Carbono , Fotobiorreactores , Biodegradación Ambiental , Nitrógeno , BiomasaRESUMEN
This study aimed to develop efficient microbial fuel cells (MFCs) for integrated bioelectricity, biodiesel feedstock production and wastewater treatment. Among wastewaters tested, MFC fed with anaerobic digester effluent from rubber industry gave the maximum power density (55.43 ± 1.08 W/m3) and simultaneously removed COD, nitrogen and phosphorus (by 72.4 ± 0.9%, 40.5 ± 0.8% and 24.4 ± 1.5%, respectively). 16S rRNA gene analysis revealed that dominant microbial communities were: Firmicutes (43.68%), Bacteroidetes (25.41%) and Chloroflexi (15.02%), which mostly contributed to bioelectricity generation. After optimizing organic loading rate, photosynthetic oleaginous microalgae were applied in cathodic chamber in order to increase oxygen availability, secondarily treat anodic chamber effluent and produce lipids as biodiesel feedstocks. Four MFCs with photosynthetic-cathodic chamber connected in vertical cascade could improve power density up to 116.9 ± 15.5 W/m3, sequentially treat wastewater, and also produce microalgal biomass (465 ± 10 g/m3) with high lipid content (38.17 ± 0.01%). These strategies may greatly contribute to sustainable development of integrated bioenergy generation and environment.
Asunto(s)
Fuentes de Energía Bioeléctrica , Purificación del Agua , Biocombustibles , Electricidad , Electrodos , ARN Ribosómico 16S/genética , Aguas ResidualesRESUMEN
Stress-tolerant oleaginous microalgae are promising for economical outdoor cultivation and biofuel production. This study aimed to induce acclimation and adaptive evolution of oleaginous Scenedesmus sp. SPP to tolerate crucial outdoor stresses by stepwise increasing of physicochemical factors: salinity, light intensity and temperature. The acclimatized strains showed better growth and accumulated 20-30% higher contents of lipids and chlorophylls. The adaptive-evolved strain showed greater tolerance to culture stresses by giving > 2-fold higher biomass under nitrogen rich and accumulating > 1.5-fold higher lipid content under nitrogen starvation compared to the parental strain. Moreover, stepwise increasing of multi-stresses successfully induced the multi-tolerance of the adaptive-evolved strain and gave the highest lipid content of 44.1 ± 1.5%. The extracted lipids from acclimatized/evolved strains show improved prospect fuel properties in terms of high cetane number and oxidative stability. These results show the effectiveness of stepwise-incremental physicochemical factors to intensify potential of microalgae for outdoor cultivation and as biodiesel feedstocks.