Discipline: Biological Sciences
Subcategory: Microbiology/Immunology/Virology
Session: 4
Room: Embassy
PHILIP J YEBOAH - North Carolina A&T State University
Co-Author(s): Salam A. Ibrahim, North Carolina A&T State University, NC, Greensboro.Abdulhakim A. Eddin, North Carolina A&T State University, NC, Greensboro.Tahl Zimmerman, North Carolina A&T State University, NC, Greensboro.Raphael D. Ayivi, North Carolina A&T State University, NC, Greensboro.Alaina D. Brock, North Carolina A&T State University, NC, Greensboro.Namesha D. Wijemanna, North Carolina A&T State University, NC, Greensboro.
Lactic acid bacteria (LAB), with some classified as probiotics, are essential requirements for dairy starter cultures in fermented dairy products such as yogurt and cheese. The biosynthesis of significant metabolites is enhanced by different ingredients such as nitrogen in the fermentation medium; however, due to the high cost of these ingredients, less expensive alternatives are needed. L. bulgaricus is one of the LAB found in yogurt and is responsible for the yogurt’s desirable characteristics, health benefits and resultant consumer acceptability. The development of a fermentation medium that meets all the nutritional requirements for LAB cell growth and viability would thus have a major effect on how L. bulgaricus produces the key metabolites that help to improve human health. In the present study, we examined the impact of different nitrogen sources such as X-Seed and MG yeast extracts on the growth and viability of two strains L. bulgaricus (S22, and LB6). The standard De Man, Rogosa, and Sharpe (MRS) media composition was modified by substituting the nitrogen content with alternative plant-based nitrogen sources X-Seed (basal media), 780MG and 532MG in different blends of 0.3g/250mL and 0.6g/250mL after testing for several blends. The L. bulgaricus strains were propagated overnight, washed with phosphate buffer and then inoculated to achieve the final inoculum level of 2-3 Log CFU/ml. Samples were then anaerobically incubated at 42oC for 12 hours. Growth was evaluated at different time intervals by measuring the turbidity using the spectrophotometer at optical density (OD610nm). Both the pH values and total bacterial counts were recorded at the end of the incubation period.The results showed that bacterial growth was higher compared with MRS broth when the nitrogen sources were blended at 0.3g of 780MG and 0.6g of 532MG with an optical density OD610mm (1.27 and 1.14) for L. bulgaricus strains (S22, and LB6) respectively. In addition, the blend of 0.3g of 532MG and 0.6g of 780MG showed a high bacterial growth with an optical density OD610mm (1.05 and 1.06) for L. bulgaricus strain (S22, and LB6) respectively, compared to the bacterial growth in MRS that showed an OD610mm (0.81, 0.76) for L. bulgaricus strain (S22, and LB6) respectively. For the bacterial counts, our results indicated that there was no significant difference when the compensation for 780MG and 532MG was used compared to the control (MRS). However, for the pH values, our results showed that there was a significant difference (P < 0.05) between values obtained for the nitrogen source blends of 780MG and 532MG and the MRS control.These findings demonstrated that the growth of L. bulgaricus was efficiently supported by the alternative nitrogen sources X-Seed, 780MG and 532MG. Such promising results using alternate nitrogen sources could thus be recommended for LAB fermentations.Keywords: Lactobacillus bulgaricus, Growth media, Fermentation, Nitrogen sourceCorresponding author: Salam A. Ibrahim, Ph.D. ibrah001@ncat.edu
Funder Acknowledgement(s): This research was made possible by Grant or project Number NC.X308-5-18-170-1 from the National Institute of Food and Agriculture (NIFA). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of NIFA.
Faculty Advisor: Dr. Salam Ibrahim, ibrah001@ncat.edu
Role: I was the main student who was involved in every stage of the research with the help and supports of my advisor.