In an SSF process, the solid substrate not only supplies the
nutrients to the microbial culture growing in it, but also serves
to anchor the cells. Sometimes, the solid substrates used for
fermentation, being agro byproducts, mightlack nutrients and
so external supplementation might positively contribute to
enzyme production (Sumantha et al., 2005). Because of the
deficit of nitrogen in the potato pulp powder, the samples
were enriched with yeast extract and polypeptone (Table 2).
The PPP supplemented with polypeptone and yeast extract
yielded 18.68 U/g of acid protease compared with 2.85 U/g
for PPP alone. Supplementation of 1% peptone and 1% yeast
extract to coffee by products dramatically increased protease
and xylanase production (Murthy and Naidu, 2010, 2012). SSF
is similar to the natural habitat offungi and the results showed
significantly enhanced protease activity, thus increasing