The relationship between vitamin B12 concentrations in milk and the archaeal and bacterial communities in the bovine rumen

Vitamin B12 (cobalamin) is a complex molecule that is synthesized by only certain bacteria and archaea but is essential for cell metabolism within many eukaryotes. Humans lack the ability to synthesize vitamin B12; however, it is critical for DNA production, and the prevention of megaloblastic anemia and neuropathy. Animal products, especially dairy products, are a good source of dietary vitamin B12 for humans since vitamin B12 is not destroyed by the pasteurization process and survives for extended periods at refrigeration temperature. Vitamin B12 in dairy products is more readily absorbed than its synthetic counterpart, which is found in supplements. However, there is large variability in vitamin B12 concentration of Canadian milk products which can range from 16-57% of the daily recommend intake. The microbial composition of the bovine rumen is likely the greatest contributor to the variability of vitamin B12 concentrations; however, the bacterial population in this environment is considerably influenced by host variability, host-management, diet and geography. In addition to the synthesis of vitamin B12, some bacterial phylotypes are affiliated with the consumption of vitamin B12. Certain bacterial populations that lack the capacity of vitamin B12 biosynthesis, are correlated with high levels of vitamin B12, indicating that microbial consumption may also play an important role in concentration variability. Additionally, few studies have analyzed the impact of archaeal communities on the concentrations of vitamin B12 in the rumen and by proxy in milk. This project will characterize the abundance and diversity of archaea and bacteria in the rumen and establish a correlation between the bacterial and archaeal community composition and vitamin B12 production.