Submerged cultures were used to study the influence of  various carbon sources on the
mycelial biomass and exopolysaccharide production of  Pleurotus  ostreatus. The antimicrobial and
antioxidant activity of   the exopolysaccharide were also determined.   The yield of  mycelial
biomass of  7.06 g/l, 5.12 g/l, 4.66 g/l, and 2.96 g/l was obtained by utilization of  maltose,
glucose,  lactose  and  starch  as  a  carbon  source,  respectively.  Furthermore,  in  the medium
containing maltose, lactose, glucose, and starch produce 100.05 mg/l, 97.73 mg/l, 78.63 mg/l,
and 70.45 mg/l of  exopolysaccharide, respectively.  The assay of  antimicrobial and antioxidant
activity showed that the exopolysaccharide is more active to inhibit the growth of  B. subtilis
rather  than  those  of  E.  coli  and  S.  cerevisiae. Furthermore,  the  exopolysaccharide was  also
indicated  to have antioxidant activity.