Recent Advances in Microbial Levan Production: Strategies for Yield Enhancement and Sustainability

Levan is a fructose-based polysaccharide with prebiotic potential and expanding applications in the food, biomedical, and industrial sectors. However, its large-scale production is limited by heterogeneous performance data, nonstandardized yield reporting, and suboptimal process design. This review presents an integrative bioengineering analysis of levan production by linking microbial diversity, levansucrase genetic regulation, enzyme functionality, and key process parameters. Based on 81 studies, substantial variability in levan production is observed, largely due to differences in cultivation strategies and analytical methods. Oxygen transfer limitations and substrate concentrations are identified as critical yet underexplored factors affecting productivity and scalability. Downstream processing challenges are also highlighted, particularly regarding their impact on product molecular weight, purity, and process sustainability. In addition, sustainability constraints are discussed in relation to energy and solvent-intensive recovery operations. Overall, this review proposes a unified bioengineering framework to support the development of more scalable, standardized, and efficient levan production systems.