Moreover, in order to reduce the hyaluronidase activity
releases by S. zooepidemicus we have included 15 mg L−1 of
polystyrene (Mw = 990 kDa, Sigma) in the culture media. In all cases,
the initial pH was adjusted to 6.7 and the media were sterilised
at 121 ◦C for 15 min. Cultures were carried out in duplicate using
a glass 2 L-bioreactor with a working volume of 1.8 L. All fermentations
were performed without aeration at 37 ◦C, with agitation
of 500 rpm and the pH was automatically controlled with sterile
5 M NaOH. In the fed-batch cultures, the reducing sugars profiles
were always maintained above 10 g L−1 by repeated added of sterile
glucose solution of 500 g L−1.