Rhodotorula Mucilaginosa as a Microbial Platform for Sustainable Lipid Production: Achievements, Bottlenecks, and Future Perspectives

The growing demand for sustainable alternatives to fossil-derived products has intensified interest in microbial lipids, also known as single-cell oils (SCOs), as renewable feedstocks for biofuels, oleochemicals, food ingredients, cosmetics, and other biobased products. Among oleaginous microorganisms, Rhodotorula mucilaginosa has emerged as a particularly promising yeast due to its metabolic versatility, ability to accumulate substantial amounts of intracellular lipids, and capacity to utilize a wide range of renewable and low-cost substrates. Over the last two decades, research on R. mucilaginosa has evolved from laboratory-scale investigations focused on lipid accumulation under controlled conditions to more sophisticated approaches involving agro-industrial waste valorization, process intensification, integrated biorefineries, and the simultaneous production of lipids and high-value metabolites such as carotenoids. This review critically examines the historical development, current advances, and future prospects of R. mucilaginosa as a microbial platform for lipid production. Particular attention is given to the physiological and metabolic traits underlying lipid biosynthesis, the evolution of cultivation strategies, and the utilization of alternative carbon sources, including crude glycerol, molasses, lignocellulosic hydrolysates, and food-processing residues. Recent advances in fed-batch cultivation, bioreactor operation, process optimization, and co-production strategies are discussed, highlighting the transition from single-product processes toward integrated biorefinery concepts. Despite significant progress, several challenges continue to hinder large-scale implementation, including substrate variability, limited volumetric productivity, downstream processing costs, and the need for economically competitive lipid recovery technologies. Future perspectives are explored in the context of metabolic engineering, synthetic biology, artificial intelligence-assisted bioprocess optimization, and carbon-efficient biorefineries. The evidence reviewed indicates that R. mucilaginosa has considerable potential as a versatile microbial platform for sustainable lipid production and multiproduct biomanufacturing, provided that biological performance can be coupled with scalable, economically viable, and environmentally responsible process design.