Abstract
Photosynthetic organisms use sunlight, carbon dioxide, water and mineral nutrients to produce biomass and molecular oxygen, also supporting the growth of heterotrophic organisms through the food web. Microalgae are responsible for about half of global C fixation and enclose an exceptionally variegated group of species, characterized by both phylogenetic and metabolic diversity, which is a precious source of biodiversity both for ecophysiological studies and biotechnological applications. Microalgae growth and productivity are continuously challenged by perturbations in the physico-chemical parameters of their habitat, like light intensity, nutrient chemical form and concentration, temperature. Thus, changes in microalgae distribution and abundance have been predicted also due to climate change. In INPHOMARE, 3 research units from UNIVPM, UNIBO and UNIPD will cooperate to deepen our understanding of the physiological and molecular mechanisms of nutrient uptake, assimilation and resources allocation in marine microalgae. Seven species of marine microalgae have been selected based on their phylogenetic position, environmental role, and potential applications. INPHOMARE will focus particularly on Nitrogen and Sulfur assimilation metabolism and on the characterization of photosynthesis, the primary energy source for photosynthetic cells, by challenging selected microalgae with nutrient limitation, various light intensities, and by mimicking temperature variations due to climate change. INPHOMARE aims at deciphering the molecular mechanisms regulating nutrient assimilation and photosynthesis and the adaptations which occurred in such processes during the evolution of diverse groups of algae. Further findings will lead to unraveling how species-specific adaptations in resources assimilation and allocation contribute to shaping dominant phytoplankton communities as a function of environmental variations. Our objectives will be tackled using a combination of physiological and molecular studies, in addition to the generation of strains with altered expression of key genes involved in the processes under investigation. Project results will be widely disseminated and communicated to different target audiences, from the scientific community to the citizens and the industry sector. The added value of INPHOMARE is its relevant impact linked to the scientific, environmental and technological values of microalgae. The project will contribute to the exploration of biodiversity and to create a holistic view of photosynthesis and cell metabolism, pivotal for a knowledge-based genetic improvement to exploit photosynthetic organisms as high-quality and cost-efficient living factories in industrial sectors. Further, the project will increase the knowledge for the correct management of marine resources, also in view of climate change, aiming at limiting their impacts on coastal ecosystems, as well as on the economy.
Results achieved
The INPHOMARE project advanced our understanding of the physiological and molecular mechanisms that regulate nutrient assimilation, photosynthesis, and resource allocation in marine microalgae. Focusing on nitrogen (N) and sulfur (S) metabolism, photosynthetic regulation, and acclimation strategies, the project investigated multiple microalgal species representing diverse phylogenetic groups. These organisms were challenged under controlled variations in nutrient availability, light regimes, and temperature, and their responses were characterized through integrated physiological, biochemical, and molecular approaches. A major achievement was the generation and characterization of Nannochloropsis oceanica mutants lacking the nitrate transporter genes NRT2.1 and NRT2.2, produced via CRISPR/Cas9 editing. Functional analyses revealed that NRT2.2 is essential for nitrate uptake following nitrogen starvation, a finding supported by growth assays and by the plasma-membrane localization of NRT2.2–YFP. Parallel analyses of biomass composition before and after N starvation provided insights into the metabolic consequences of NRT2.2 inactivation. Complementary studies examined the effects of sulfate limitation on photosynthesis and cell composition in green algae, diatoms, and dinoflagellates. This work included the development of cultivation protocols for S-limited dinoflagellates and the establishment of an SPME-GC/MS method for quantifying DMS and DMSP, key compounds in marine biogeochemical and climatic processes. Across species, the project identified both shared and lineage-specific acclimation strategies to nutrient stress and environmental variability. INPHOMARE also generated preliminary data enabling future research, including the characterization of the photosynthetic apparatus of Dunaliella salina and Tetraselmis suecica, optimization of molecular protocols for S-assimilation enzymes, and exploratory attempts toward D. salina transformation. The project’s outcomes were disseminated through outreach activities, scientific presentations, and peer-reviewed publications, including one article already published. Overall, INPHOMARE achieved its objectives by (i) deepening knowledge of the diversity and evolution of nutrient assimilation and photosynthesis in marine microalgae, (ii) identifying common and species-specific acclimation responses to environmental change, and (iii) elucidating how environmental conditions shape metabolic resource allocation. This knowledge enhances our ability to interpret past shifts in phytoplankton communities, forecast future scenarios under climate change, and supports the knowledge-based development of microalgae as sustainable bio-factories for biofuels, antioxidants, and bioplastic precursors.Dettagli del progetto
Responsabile scientifico: Laura Pezzolesi
Strutture Unibo coinvolte:
Dipartimento di Scienze Biologiche, Geologiche e Ambientali
Coordinatore:
Università Politecnica delle Marche(Italy)
Contributo totale Unibo: Euro (EUR) 67.335,00
Durata del progetto in mesi: 24
Data di inizio
05/10/2023
Data di fine:
28/02/2026
