Effects of nutrients, pH and water potential on exopolysaccharides production by a fungal strain belonging to Ganoderma lucidum complex

PAPINUTTI

BIORESOURCE TECHNOLOGY

Elsevier

Año: 2010 vol. 101 p. 1941 - 1946

0960-8524

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Exopolysaccharide (EPS) production by Ganoderma lucidum in response to different culture conditions was studied. Cellulose and glucose, in defined media, resulted in the more efficient enhancers of EPS production among the carbon sources tested. In natural media cultures containing glucose and malt extract exhibited a marked increase (up to 29-fold) respect to defined media. Subsequently, high malt extract and glucose concentrations were tested. G. lucidum produced two fractions of EPS, water-soluble and water-insoluble under these culture conditions. The maximum value (15 g L-1) was reached at 21 days in the medium containing 60 g L-1 malt extract and 40 g L-1 glucose. The incomplete utilization of reducing sugars by the fungus in these media suggested that not only did high malt extract and glucose concentrations play a role in EPS production but the water activity might also be involved. A factorial uniform experimental design to test the effect of malt extract, polyethylene glycol (PEG) (as water activity depressor), and initial pH on specific EPS production was applied. G. lucidum showed to be a more efficient specific EPS (mg EPS per g mycelium) producer at pH 3.5 in cultures containing the highest PEG and malt extract concentrations.