Co-cultivation of Chlorella minutissima with bacteria for enhanced biomass and bioactive productivity: a synergistic approach for sustainable biorefinery
摘要
Chlorella minutissima holds promise for sustainable biorefineries, producing biomass, lipids, and bioactives. This study investigates co-cultivation with Azospirillum brasilense and Pseudomonas fluorescens in low-nitrogen BG-11 medium to enhance productivity, addressing gaps in plant growth-promoting rhizobacteria (PGPR) applications for this alga. Optimized 1:10 bacterial-algal ratios yielded 2.5 g L⁻1 biomass (1.6-fold over monoculture’s 1.5 g L⁻1) and 38% lipid content (1.8-fold over 15%). Bioactives increased significantly, with 45 mg gallic acid equivalents g⁻1 phenolics and 12 mg g⁻1 carotenoids, achieving 75% DPPH radical scavenging and 18 mm antifungal zones against Candida albicans. Hydrothermal liquefaction produced 42% bio-crude (versus 25% in monoculture). Nutrient recycling sustained 1.5 g L⁻1 biomass, reducing fresh inputs by 60% (220 mg L⁻1 nitrogen, 45 mg L⁻1 phosphorus uptake), and energy use dropped 25% to 0.8 kWh g⁻1 biomass. Potential quorum sensing contributions, indicated by 2.5-fold gene upregulation in A. brasilense co-culture, likely drive enhancements through nitrogen fixation and hormone exchange. This non-genetic approach outperforms monocultures, offering a scalable, eco-friendly platform for biofuels, nutraceuticals, and wastewater remediation. As the first optimized C. minutissima-PGPR co-culture, this study advances applied phycology by reducing costs and environmental impacts, aligning with circular bioeconomy goals. These results establish a novel, sustainable biorefinery model, with pilot-scale validation as the next step for industrial application.