Fungal (1 → 3)-α-d-glucans as a new kind of biosorbent for heavy metals

Although the fungal ability to bind heavy metals has been known for many years, it was not determined which component is responsible for this process. The aim of the study was to isolate (1 → 3)-α- d -glucans from various fungi, select the most efficient compound in the biosorption of heavy metals, and determine its characteristics. The best α-glucan for treatment of aqueous solutions from heavy metals (Ni2+, Cd2+, Zn2+, Pb2+) is the polymer isolated from Shiitake, especially its SH 37 variety. Using various techniques, it was confirmed that the studied polysaccharide consists mainly of glucose molecules (75.9%), i.e. glucose α-anomers linked by (1 → 3)-linkage (86%). The well-developed surface, low crystallinity, and the large number of –OH groups provide this polymer with good sorption properties. Probably, the main mechanism of metal uptake is metabolism-independent process that depends on the content and spatial structure of the glucans present in their cell wall.