Abstract
Pullulan is an extracellular homopolysaccharide produced commercially by the yeast-like fungus Aureobasidium pullulans. Owing to its unique physicochemical properties, such as film-forming ability, biodegradability, and non-toxic nature, pullulan has attracted significant interest for applications across diverse industries, including cosmetics, pharmaceuticals, food packaging, and agriculture. In recent years, the demand for sustainably derived biopolymers has intensified, prompting exploration of industrial waste and renewable substrates as cost-effective feedstocks for pullulan production. Despite its promising versatility, largescale commercialization remains constrained by high production costs, low yield, and limited substrate flexibility. This review critically examines the potential of microbial-based pullulan production, highlighting both technological opportunities and persistent challenges. Particular emphasis is placed on the use of alternative substrates, strain improvement strategies, and bioprocess optimization to enhance yield and reduce costs. Advances in metabolic engineering, fermentation technology, and integrated biorefinery approaches are discussed as pathways to overcome current limitations. By synthesizing recent progress and identifying research gaps, this study aims to support future innovation in sustainable pullulan production and broaden its industrial applicability. Ultimately, optimizing production parameters and diversifying microbial systems may provide a viable solution to transform pullulan into a widely accessible biopolymer for global markets.