[Lactococcus lactis capable of respiring in the presence of heme]

Lactococcus lactis undergoing respiration has fast growth rate and relatively high biomass, which is the one of the potential way of improving the production efficiency of starter. In this study, the respiration situation and metabolism changes of Lactococcus lactis strains in the presence of heme were investigated.

Twelve strains of Lactococcus lactis were examined with aerobic cultivating test. The difference of biomass and metabolites among strains were compared. Furthermore, the survival rate at storage at 4 degrees C for 30 days was also compared by testing their viable cell count.

A strain of Lactococcus lactis coded as KLDS 4.0316 could respire in the presence of heme. The biomass of KLDS 4.0316 cultivated in the present of heme increased by 50%. After being stored at 4 degrees C for 30 days, the strain cultivated under the condition without oxygen and heme was totally dead, whereas the viable cell count of strain cultivated with oxygen and heme remained 10(8) CFU/ml. Production of lactic acid decreased by 48%, compared with the strain cultivated in the absent of heme.

KLDS 4.0316 can undergo respiration in the present of heme, and the production of lactic acid decreased while the biomass increased.