A Biostat B plus 5 L fermenter (Sartorius Stedim Biotech, UK)
was used to perform fed batch experiments. Temperature and pH
was controlled at 30 C and pH 7, respectively. Dissolved oxygen
(DO) concentration was controlled at 40% in the cascade mode
using the stirring speed; the rate of air in flow was maintained constant
at 2 l/min. pH was maintained at 7 using acetic acid and 5 M
NaOH as pH control.