Diluted sweet cheese whey was prepared by diluting sweet
cheese whey (provided by ILAS S.A., Asturias, Spain) 1-fold
with distilled water (1:1) and adjusted to pH 6.5 (by adding 6 M
NaOH) prior to sterilization using a tangential microfiltration
device equipped with a 0.22 lm pore size PVDF membranecassette
(Millipore, Massachusetts, USA). Concentrated cheese
whey for fed-batch bioreactor cultures was prepared as above via
microfiltration of undiluted sweet cheese whey.