초록
Nisin production by Lactococcus lactis CECT 539 was studied in four realkalized fed-batch cultures in diluted whey with feeding with lactose- and glucose-containing substrates. The first and third cultures were fed with mixtures of whey (W) and a 400g/L concentrated glucose (CG), or with a concentrated mussel processing waste (CMPW) and CG, respectively. The second and fourth cultures were respectively performed under the same conditions as in the first and third fermentations. However, these cultures were supplemented with mixtures of W plus a 2% (w/v) yeast extract (WYE2) and CG (second culture), or with CMPW plus a 2% (w/v) yeast extract (CMPWYE2) (fourth culture) after sample extractions at 132 and 168h, respectively. From these times, each culture was fed with mixtures of WYE2 and CG, or CMPWYE2 and CG, respectively. The final concentrations of nisin obtained in the third (223.98BU/mL) and fourth (350.61BU/mL) cultures, fed with glucose-containing substrates (CG and CMPW), were considerably higher than those obtained in the first (108.00BU/mL) and second (158.53BU/mL) cultures fed with the mixture of lactose- and glucose-containing substrates (W and CG).