Abstract: Rare earth elements(REE)of praseodymium, neodymium and erbium were added into the media to investigate theireffects on the mycelial growth and polysaccharide formation by Russula sp. The experiments were carried out in freely suspended cultures using shake flasks. The results indicate that the extent of stimulation or inhibition were associated with the types and levels of rare earth elements. REE at a lower level of concentration led to a significant increase in cell concentration, production of extra cellular polysaccharide (EPS) and intracellular polysaccharide (IPS) in a submerged cultivation. In contrast, REE at a higher level of concentration led to a drastically suppressed both mycelial growth and polysaccharide formation. Rare earth elements of praseodymium, neodymium were beneficial to the promotion of the cell growth and product biosynthesis. The optimal production of biomass, EPS, IPS, TPS and yield of polysaccharides was 24.63±0.62 g/L, 1.730±0.065 g/L, 79.03± 0.00 mg/g, 3.511±0.028g/L, 7.60%±0.15%, respectively.

Key words: Russula sp., submerged fermentation, polysaccharide, rare earth elements, praseodymium, neodymium, erbium