Exopolysaccharide production by filamentous fungi: the example of Botryosphaeria rhodina

One-hundred and five fungal strains, belonging to 46 different species, were screened for exopolysaccharide production. Phytopathogenicity and, in particular, inability to produce conidia, were physiological characteristics positively associated and correlated with the fungal ability to produce polysaccharides. Among the 29 positive strains, Botryosphaeria rhodina DABAC-P82 was the most interesting reaching, when grown on optimal nitrogen source and concentration (NaNO₃ and 2.0 g l⁻¹, respectively) and culture medium pH (3.7), 17.7 g l⁻¹ of exopolysaccharide production after only 24 h of fermentation; yield and productivity were 0.69 g g⁻¹ and 0.73 g l⁻¹ h⁻¹, respectively. The purified polysaccharide was characterised as a homopolysaccharide of glucose with a molecular weight of 4.875·10⁶ Da. Studies of structural analysis indicated the presence of β-1,3 and β-1,6 linkages; the EPS structure was very similar to that of scleroglucan. This revised version was published online in August 2006 with corrections to the Cover Date.