The Green and the Invisible: Forging a Synergistic Future for Microalgae in Microbial Biotechnology

The established paradigm of microbial biotechnology, predominantly reliant on heterotrophic platforms like Escherichia coli and Saccharomyces cerevisiae , faces significant sustainability challenges due to its dependence on sugar-based feedstocks. This review contends that microalgae, as photosynthetic microorganisms, represent a pivotal and necessary expansion of the biotechnology toolkit. We articulate a compelling case for integration, highlighting their capacity for autotrophic growth using carbon dioxide and light, which decouples production from agricultural resources. Furthermore, microalgae synthesize a unique portfolio of high-value compounds, such as omega-3 fatty acids and carotenoids, and can deliver integrated ecosystem services like wastewater remediation and carbon capture. Through detailed case reports on the commercial production of astaxanthin, the evolution of the biofuel endeavor into a biorefinery model, and the emerging platform of microalgae for pharmaceutical production, we demonstrate a tangible convergence with conventional bioprocess principles. However, achieving full synergy is hindered by persistent disciplinary divides. This article provides a critical discussion of these gaps, including the need for standardized process engineering and scale-up of photobioreactors, the development of advanced genetic toolboxes, and the cultivation of an interdisciplinary workforce. By systematically addressing these challenges through collaborative efforts in synthetic biology, bioprocess engineering, and techno-economic analysis, the field can unlock a new, sustainable, and productive era for industrial biotechnology. This integration positions microalgae as a central pillar in the transition towards a circular bioeconomy.