What it is
This ingredient is the fermentation product of Aureobasidium pullulans, a polymorphic fungus that secretes a high-molecular-weight polysaccharide known as beta-1,3/1,6-glucan (sometimes called pullulan or aubasidan depending on culture conditions). In cosmetic formulas it forms a light, flexible film on the skin surface and contributes a smooth, conditioned feel, and is valued for its moisture-binding polysaccharide content. It is commonly included in serums and sun care products as a soothing, hydrating support ingredient rather than as an active UV filter.
Safety & warnings
Polysaccharide ferments of this type are generally well tolerated and are not associated with significant comedogenicity. As with any fermentation-derived ingredient, residual proteins or fungal components could in rare cases be relevant for highly sensitized individuals, but reports of irritation are uncommon at cosmetic use levels.
Origin & sourcing
Biotechnological. It is made by fermenting the fungus Aureobasidium pullulans, which naturally produces extracellular polysaccharides; the ferment broth or its purified glucan fraction is then used in cosmetics.
Questions everyone asks
What does Aureobasidium Pullulans Ferment do in a sunscreen?
It acts as a film-forming and skin-conditioning ingredient, contributing a smooth feel and helping bind moisture, rather than providing UV protection itself.
Is it the same as beta-glucan?
It is a primary source of fungal beta-glucan; the ferment supplies beta-1,3/1,6-glucan polysaccharides as its main functional component.