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- Clean production of microalgae high-value lipid fraction: influence of different pretreatments on chemical and cytotoxic profiles of Chlorella vulgaris supercritical extracts and life cycle assessmentPublication . Vladic, Jelena; Radman, Sanja; Zizak, Zeljko; Besu, Irina; Jerkovic, Igor; Galileu Speranza, Lais; Hala, Ahmad Furqan; Kovacevic, Strahinja; Gouveia, Luisa; Pereira, HugoMicroalgae have emerged as a promising natural resource rich in bioactive compounds. Health-beneficial properties of microalgae, coupled with advantageous characteristics such as high biomass productivity, adaptability, robustness, and carbon dioxide mitigation, position them as a viable solution for global sustainable food production. This study explored clean and environmentally friendly processes to enhance the recovery of lipid bioactive fractions. Microwave (MW), enzymatic (ENZ), and ultrasound (US) pretreatments were applied to improve environmentally friendly extraction of lipid-based components using supercritical CO2. The effects of these pretreatments on extraction yield, chemical profiles, and cytotoxic properties of Chlorella vulgaris (Cv) and smooth C. vulgaris (sCv) extracts were investigated. Additionally, a Life Cycle Assessment (LCA) was conducted to evaluate environmental impacts. MW pretreatment achieved the highest yield increases, from 2.58 times (Cv) to 3.15 times (sCv). UHPLC-ESI-HRMS analysis revealed shifts in the distribution of pigments and derivatives caused by pretreatments, with ENZ extracts showing the most pronounced changes: pigments increased from 9.24% (control Cv) to 40.92% (Cv) and from 12.52% (control sCv) to 71.12% (sCv). Cv extracts exhibited greater activity against MDA-MB-453 cells, while sCv extracts from US pretreatment demonstrated the strongest effect on HeLa cells. The LCA indicated reduced environmental impacts of the pretreatment-enhanced processes up to 65% compared to the control. A scenario analysis was presented to show further possible impact reduction by recirculating the CO2 solvent and substituting the energy source. These findings provide valuable insights into sustainable and scalable green processes for recovering microalgal bioactive components.
- Detection and mitigation of paraphysomonas sp., a chrysophycean responsible for the collapse of industrial tisochrysis lutea culturesPublication . José, Mélissa; Paulino, Cristina; Schüler, Lisa; Pinto, Bruno; Carneiro, Mariana; Rodrigues, Alexandre M. C.; Pereira, Filipe; Pereira, Hugo; Varela, JoãoMicroalgae are increasingly recognized as a sustainable resource to address challenges associated with climate change and population growth, owing to their capacity to produce high-quality biomass for applications in feed, food, and cosmeceuticals. However, the expansion of microalgae-based industries remains constrained by harmful biological contaminants (HBCs), which can rapidly reduce productivity, often signalled by visible changes in culture appearance (e.g., cell aggregation and discoloration), and may ultimately lead to culture collapse and substantial economic losses. In this study, the grazer Paraphysomonas sp. (Chrysophyceae) was identified as the most likely cause of Tisochrysis lutea culture collapse in a large-scale production facility using high-throughput amplicon sequencing of the 18S rDNA gene. To enable early detection of this HBC during the scale-up process, a species-specific primer pair targeting the 18S rDNA gene was developed and optimized, allowing detection of Paraphysomonas sp. at relative abundances as low as 0.1%. The contaminant was first detected at the final stage of scale-up, in a tubular photobioreactor. To further characterize the impact of the grazer and support mitigation strategies, its feeding behaviour was examined. Laboratory-scale mitigation trials showed that treatment with germanium dioxide (GeO2) at 1 mg L⁻ 1 effectively delayed contaminant proliferation and prevented culture collapse without adversely affecting T. lutea growth. These findings highlight the value of integrating molecular monitoring with targeted mitigation strategies to improve early detection and management of HBCs in industrial microalgae production systems.