Nitrogen source: an effective component for the growth and viability of Lactobacillus delbrueckii subsp. bulgaricus

Abstract

In this study, we developed and optimized a growth media by evaluating various nitrogen sources for the cultivation of Lactobacillus bulgaricus, a probiotic and an important dairy starter culture. We modified the composition of deMan, Rogosa and Sharpe (MRS) culture media and substituted the nitrogen content with alternative nitrogen sources X-Seed KAT, X-Seed Carbo Max and X-Seed Nucleo Max in various blends of 5 g/l and 10 g/l respectively. Results showed that bacterial growth was significantly higher when the nitrogen source blend KCMax (10/10) was used. The optical density (OD610 nm) of the Lactobacillus bulgaricus strains were higher (1.34 and 1.79) in the KCMax (10/10) medium than in the MRS medium (0.89 and 1.42) (P < 0.05). There was no significant difference in the bacterial counts for both the MRS medium and the KCMax (10/10) medium, and all bacterial counts were estimated at 8 log CFU/ml. The buffering capacity of KCMax (10/10) was also tested and supplemented with l-histidine and was significantly different (P < 0.05) than that of the MRS control medium. Calcium supplemented in the KCMax (10/10) also served as a cryoprotectant for the cells during freezing and freeze-drying. Bacterial counts of the recovered calcium-treated freeze-dried cells were statistically significant (P < 0.05). We hypothesized that alternative nitrogen sources such as selected yeast extracts from the X-Seed brand of complex nitrogen sources could efficiently support the viability of Lb. bulgaricus. Our results thus suggested the growth of Lb. bulgaricus was efficiently supported by the X-Seed KAT, X-Seed Nucleo Max and X-Seed Carbo Max nitrogen sources. Consequently, these alternative nitrogen sources could potentially be recommended for dairy starter culture fermentations.

Effect of walnut peptide‐ZnO nanocomposites on the colon adhesion behavior of Lactobacillus rhamnosus LRa05

“…However, the proliferation‐promoting effects of these peptides on LRa05 were proportional to their concentrations and exhibited a certain concentration dependence. Nitrogen source has a vital role for the efficient growth of lactobacilli (Ayivi et al., 2022); therefore, different sequences of walnut‐derived peptides (PW5, WN5, AE6, and WE7) may be utilized by LRa05 growth as a source of nitrogen. On the other hand, the LRa05 fitness in the walnut peptide‐ZnO nanocomposites groups was significantly higher than in the individual n ZnO ( p < 0.05) group, particularly for medium and high concentrations of walnut peptides.…”