THE IMPACT OF ALTERNATIVE NITROGEN SOURCES ON THE GROWTH AND VIABILITY OF LACTOBACILLUS DELBRUECKII SUBSP. BULGARICUS
In this study, we developed and optimized a growth medium using various nitrogen sources for the cultivation of Lactobacillus delbrueckii subsp. bulgaricus, a probiotic and essential dairy starter culture. The composition of deMan, Rogosa and Sharpe (MRS) culture medium was modified, and the nitrogen content was replaced by alternative nitrogen sources X-Seed Nucleo Max, X-Seed KAT, and X-Seed Carbo Max in various blends of 5g/L and 10g/L respectively. Results showed that bacterial growth was significantly higher when the nitrogen source blend KCMax (10/10) was used. The optical densities (OD610nm) of the Lb. bulgaricus strains were significantly higher in the KCMax (10/10) medium than in the MRS medium. There was no significance in bacterial counts for both the MRS and the KCMax (10/10) medium, and all bacterial counts were estimated at 8 Log CFU/ml. The buffering capacity of the KCMax (10/10) medium was also tested and supplemented with L-histidine and was significantly higher than that of the MRS control medium. KCMax (10/10) also supported the freeze stability and viability of the bulgaricus cells during freezing and freeze-drying operations. Our results suggest that the alternative nitrogen sources X-Seed Nucleo Max, X-Seed KAT and X-Seed Carbo Max can substantially support the growth of lactic acid bacteria as demonstrated with Lb. bulgaricus. These alternative nitrogen sources could thus be recommended for LAB fermentation and for the cultivation of dairy starter cultures.
Steps to reproduce
Procedures are documented in the attached supplementary files