## 2 Marine Microalgae Diversity and Biotechnological Relevance
These data are used to build predictive models of metabolic flux and identify novel biosynthetic routes. Case studies have shown that omics-guided engineering can lead to 2-3-fold increases in target compound yields under optimised culture conditions. These advances are essential for strain selection, metabolic pathway optimisation, and precision cultivation [27; 28]. Artificial intelligence (AI) and machine learning are also emerging as tools for real-time process optimisation in photobioreactors. AI-assisted monitoring systems are being used to modulate light cycles, nutrient delivery, and CO2 supplementation dynamically, thereby improving both biomass productivity and metabolite concentration [29]. The omics revolution has significantly enhanced our understanding of microalgal biology. These high-throughput tools are used to dissect biosynthetic pathways, elucidate stress response mechanisms, and identify genes responsible for metabolite production. Genomic and transcriptomic data, for instance, can reveal upregulated pathways during nutrient deprivation, pointing to potential targets for metabolic engineering [30]. Moreover, multi-omics integration allows for holistic systems biology approaches, enabling predictive modelling of cellular behaviour under varying conditions. Such insights are crucial for the design of next-generation bioreactors and cultivation regimes [31]. Genetic engineering in microalgae, while still developing, has made significant strides with tools such as CRISPR/Cas9, Agrobacteriumium-mediated transformation, and synthetic biology circuits. These tools allow for strain enhancement through gene knock-ins or knockouts aimed at improving yield, resistance, or biosynthetic specificity. For example, the transformation of _Paelova lutheri_ with a desaturase gene significantly increased its PUFA content, demonstrating the practical utility of such approaches [32]. In parallel, synthetic biology is being used to construct modular pathways for the de novo synthesis of complex compounds, such as pharmaceuticals and recombinant proteins. This expands the potential of microalgae beyond natural metabolite production into the realm of custom biomanufacturing [33]. Marine microalgae are increasingly recognised as sources of functional foods, nutraceuticalals, and dietary supplements. The n-3 fatty acids EPA and DHA, commonly derived from fish, can be sustainably sourced from microalgae without the risks of bioaccumulated toxins. Other compounds like astaxanthin and lutein are marketed for their antioxidant and eye-health benefits [34]. Microalgae also hold promise in clinical nutrition, with ongoing studies evaluating their potential in managing chronic diseases such as diabetes, hypertension, and neurodegeneration. The approval of _Chlorella_ and Spirulina as Generally Recognised as Safe (GRAS) ingredients has facilitated their incorporation into a variety of food and beverage products [35]. Beyond health applications, microalgae serve as agents of environmental remediation and contributors to sustainable manufacturing. Their ability to uptake nitrogen, phosphorus, and heavy metals makes them suitable for treating municipal and industrial wastewater. Moreover, lipid-rich strains are used in the production of biofuels, bioplastics, and green solvents [36]. Their use in carbon capture and utilisation is also notable, with pilot projects demonstrating that flue gases from power plants can be directly used to enrich algal cultures, turning waste into biomass [37]. Recent innovations in co-cultivation techniques, where microalgae are grown alongside bacteria or other algae, have shown great promise for enhancing productivity and uncovering novel metabolic interactions. These systems mimic natural symbioses, fostering nutrient recycling, quorum sensing, and co-metabolite production. Studies have revealed that such ecology-driven approaches can boost the synthesis of bioactive compounds beyond what is observed in monocultures.