Daniel Kurpan

Climate change mitigation requires solutions that reduce greenhouse gas (GHG) emissions, especially in the agricultural sector, which is responsible for most of Brazil's emissions. Synthetic fertilizers contribute to GHG emissions due to their production, transportation, and use processes. This work quantified and compared the environmental impact associated with replacing synthetic fertilizers imported by Brazil with a biofertilizer produced from the cultivation of Limnospira sp. in brewery effluent. The resulting biomass was used to produce a cyanobacterium-based biofertilizer, which was later applied to the cultivation of barley ( Hordeum vulgare ), adopting the concept of circular economy. The life cycle assessment (LCA) used a software database (Open LCA and Ecoinvent 3.8) to quantify GHG emissions in the production and transportation of the biofertilizer and a chemical fertilizer (NPK 5-20-20). The LCA demonstrated that the biofertilizer had a 2.7-fold reduction in global warming impact relative to the NPK fertilizer, with emissions of 485.84 kg CO ₂ -eq/ton vs. 1,312.75 kg CO ₂ -eq/ton. A sensitivity analysis was performed using fertilizer substitution scenarios of 50% and 75%, indicating emission reductions of 1.46 and 1.89 times, respectively. These findings indicate that total and partial replacements benefit the environment and strengthen sustainability in the agricultural and industrial sectors.

Microalgal lipids are promising sustainable feedstocks for high-value functional ingredients. However, the influence of cultivation-driven lipid composition on enzymatic conversion remains poorly understood. This study integrated cultivation strategy and enzymatic upgrading to tailor Neochloris oleoabundans lipids for mono- and diacylglycerol (MAG and DAG) production. Heterotrophic cultivation achieved a maximum dry biomass concentration of 2.78 ± 0.14 g L⁻¹, whereas autotrophic cultivation reached 0.39 ± 0.01 g L⁻¹, confirming the superior biomass productivity of heterotrophic metabolism. Lipid fractions obtained under both trophic conditions were characterized and subjected to glycerolysis catalyzed by Novozym 435 under a 5:1 glycerol-to-oil ratio for 16 h. Heterotrophic oils, characterized by triacylglycerol-rich and low-free fatty acid (FFA) profiles, achieved higher MAG + DAG conversion (45%), while autotrophic oils reached 43% conversion despite elevated FFAs and polar lipids. The presence of FFAs, pigments, and phospholipids in non-refined microalgal oils influenced catalytic behavior, reducing conversion efficiency and favoring competing esterification and hydrolysis pathways. These findings demonstrate that substrate purity, acylglycerol distribution, and cultivation-specific lipid architecture strongly affect lipase performance, highlighting oil refining and cultivation optimization as key strategies for improving sustainable MAG and DAG production.

To boost the local microalgae sector, Switzerland needs to better understand the current state of the industry, which is not fully represented in the existing literature. Only by identifying the strengths and weaknesses of the Swiss microalgae industry, will the country be able to develop strategies toward a strong and sustainable sector in the future. This work provides the first structured assessment of Switzerland’s fragmented and poorly documented microalgae sector through desktop research and an online survey of the country’s microalgae stakeholders. First, research articles with Swiss authors and patents with Swiss applicants were mapped. Then, a survey consisting of 8 questions was designed to gather information about the location, purpose, employees, production capacity, activities, and installations of 42 organizations with a research and/or commercial focus. The growing number of organizations working with microalgae in Switzerland is dominated by small companies (<50 employees) that provide services rather than biomass or bioproducts. Microalgae biomass production is about 2 tons DW per year and is also dominated by small-scale producers (<100 kg DW per year). One third of Swiss companies that sell microalgae-based products produce their own biomass abroad or purchase from abroad. Our findings highlight the growth potential of the Swiss microalgae sector. This systematic summary of research interests, technological innovations, and current market parameters is the first step toward future improvements in the sector.

To reduce pressure on capture fisheries, sustainable aquaculture must decrease its dependency on fish meal and fish oil. Microalgae are a promising substitute due to their complete nutritional profile and low-footprint production process. This study examined the use of the cyanobacterium Limnospira maxima (commercially known as Spirulina) as a partial substitute for fish meal in feed for juvenile Nile tilapia (Oreochromis niloticus). We developed isoproteic (36%) and isoenergetic (3000 kcal kg⁻¹) fish feed formulations containing 0% (control), 10%, 20%, 30%, or 40% L. maxima dry biomass. The experimental diets were then fed to 360 juvenile O. niloticus (1.32 ± 0.35 g) for 85 days using a randomized experimental design. The hepatic, intestinal, and muscle (fillet) tissues of the fish were collected for morphophysiological, fatty acid, and proteomic analyses. The intestinal coefficient, number of intestinal villi, villus height, and hepatosomatic index were essentially the same for all treatments (p > 0.05). Treatments containing 20–30% L. maxima exhibited a higher degree of unsaturation and better dietary fat quality. A greater abundance of the enzymes SOD, GSR, PRX1, and PLD3 in the experimental groups indicated higher antioxidant activity, whereas a greater abundance of acyl-CoA dehydrogenases indicated better use of fatty acids as an energy source. These trends were more evident in the 20–30% inclusion range. Thus, adding L. maxima to fish feed improves farming performance, fish health, and product quality. The results encourage the use of microalgae to promote more sustainable aquaculture.

Arthrospira platensis and Chlorella vulgaris are popular commercialised microalgae due to their benefits and relatively easy large-scale cultivation. However, recent advances in biotechnology have revealed a new range of promising strains with industrial potential but limited current markets. To bridge the gap in the existing literature, this study provides a comprehensive and simultaneous biochemical characterisation within a unified analytical framework of six additional strains: Phaeodactylum tricornutum, Tetraselmis chuii, Nannochloropsis oceanica, Scenedesmus almeriensis, Tisochrysis lutea, and Skeletonema costatum. The analyses included macromolecular composition, amino acid and fatty acid profiles, and volatile organic compound composition. Key results identified P. tricornutum and T. chuii as high-quality protein alternatives, reaching protein concentrations of 31% and 41% (dw), respectively, with essential amino acid profiles (arginine and tryptophan) that match commercial standards. Additionally, specific carbohydrate and lipid strengths were identified: P. tricornutum showed a high carbohydrate content (37%), while N. oceanica exhibited elevated levels of palmitic, palmitoleic, eicosapentaenoic, and arachidonic acids, marking them as versatile candidates for nutritional applications. Finally, volatile organic compound analyses revealed distinct aroma profiles, highlighting the potential of less-exploited microalgal strains for the food and feed sectors.

The efficiency and outcomes of mechanically disrupting microalgal cell walls depend on various factors and are case-specific. In general, bead milling is reproducible and scalable, and it can successfully increase the digestibility of microalgal biomass. However, its effects on the aroma of microalgal biomass have not yet been assessed. This study is the first to report the use of the NanoWitt-100 bead mill to break down microalgal biomass. Optimization of processing time and cell concentration revealed that the optimal conditions were a milling time of 15 min, and a cell concentration of 50 g L ⁻¹ . Under these conditions, we then compared the in vitro protein and amino acid digestibility as well as volatile organic compound (VOC) profiles of undisrupted and disrupted samples. Bead milling substantially increased total protein digestibility from 62.2 ± 2.28 to 99.7 ± 0.06%. The digestibilities of all amino acids and the in vitro digestible indispensable amino acid scores (DIAAS) also increased. Although the release of VOCs increased in the disrupted biomass, the VOC profiles indicated an improvement in the final aroma of the biomass. This outcome was due to a reduction in acid concentration and an increase in ester concentration as a proportion of the total VOCs. Overall, these findings support further scalability tests, sensory analysis, and in vivo trials using microalgae disrupted with the bead mill NanoWitt-100.

Microalgae have been proposed for the bioremediation of wastewater, as well as for biofertilization and biostimulation of several plant species. This study used Limnospira sp. biomass produced in brewery wastewater to formulate a pelletized biofertilizer. Its efficacy in promoting barley (Hordeum vulgare) growth was then compared with chemical fertilizers and a control group without fertilization on lab- and pilot-scale setups. On a 100-day lab-scale experiment under controlled light (260–280 µmol photons m⁻² s⁻¹) and temperature (20 ± 2 °C), minor differences in plant growth were observed, whereas the elemental composition of the barley plants did not differ, including toxic elements. On a pilot-scale agricultural setup (5 m²) under environmental conditions, barley productivity, protein content, and the percentage of class I grains (diameter ≥ 2.5 mm) significantly increased based on the different dressing techniques used (p < 0.05). Using the microalgae-based biofertilizer for both base and top dressing increased productivity, protein content, and grain size (% class I) by 26.9%, 14.4%, and 8.78%, respectively, compared to using chemical fertilizers (NPK 5:20:20 and urea). These results indicate the great potential of using microalgae biomass from wastewater treatment as biofertilizer for more sustainable agriculture.

Lipids obtained from microalgae have recently received significant attention from the energy and food industries. Microalgae are promising alternatives and are more sustainable sources of lipids for the food industry, which faces a growing demand for food and increased environmental awareness among consumers. This study provides a bibliometric review of research articles published between 2019 and 2024 with the aim of understanding the future trends and tendencies of the applications of microalgal lipids in the food industry. A thorough assessment of 255 articles retrieved from the Scopus database showed an apparent decrease in the number of publications per year within the analyzed timeframe. The predominant focus has been basic research conducted on a lab-scale using chlorophytes (green algae) to optimize lipid production by modulating physicochemical cultivation parameters (i.e., nutrient availability, temperature, light, and pH). Lipids were mainly extracted using the Bligh and Dyer or Folch methods, quantified gravimetrically, and characterized using gas chromatography coupled to mass spectrometry. Publications referring to polyunsaturated fatty acids, such as omega-3 and omega-6, were the most abundant. The results emphasized the significance of microalgae as a promising biotechnological platform for the production of lipids within the food industry.

Currently, all feed and food come from plant- or animal-based production systems. The potential of the natural biodiversity of microorganisms for the highly efficient production of nutrients has yet to be leveraged. We present an overarching concept that ranges from the development of a national collection of regional microalgae to the decentralised production of nutrient-rich biomass for animal feed production. The focus is on the substitution of classic plant-based feed to reduce competition for arable land, to increase the nutritive value of animal-based food, and to reduce methane emissions from ruminants. The photoautotrophic and mixotrophic cultivation of microalgae are well aligned with the goals of CO2 fixation and the later contribution to the valorisation of side streams from the food industry. We also present the initial results on strain adaptation to diverse cultivation conditions.