Question

Which one of the following is a lactic acid bacteria that synthesize vitamin B12?

• A. Bifidobacterium
• B. Brevibacterium
• C. Propionibacterium
• D. Pediococcus

Hint:

Dairy Vitamin Synthesis:
Vitamin $\text{B}_{12}$ (Cobalamin) Producer = PROPIONIBACTERIUM (P. freudenreichii).
Riboflavin ($\text{B}_2$) Producers = Lactiplantibacillus plantarum, Leuconostoc.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Dairy biotechnology and cobalamin biosynthesis: Propionibacterium freudenreichii is an industrially utilized dairy propionic acid bacterium that biosynthesizes substantial intracellular quantities of active Vitamin B12 (cobalamin).
Key Formula or Approach:
\[ \text{Dairy Fermentation (Swiss Cheese): } \textit{Propionibacterium freudenreichii} \xrightarrow{\text{De Novo Biosynthesis}} \mathbf{Vitamin \text{ } B_{12} \text{ (Cobalamin)}} \]

Step 2: Detailed Explanation:
In microbial biotechnology and vitamin synthesis in fermented dairy products:
1. {Propionibacterium (specifically {Propionibacterium freudenreichii and P. shermanii) (C): High-GC dairy propionic acid bacteria used as ripening starter cultures in Swiss/Emmental cheese. They possess the complete complex 30-gene enzymatic machinery for de novo biosynthesis of Vitamin B12 (Cobalamin), accumulating up to $30 - 40\;\mu\text{g/g}$ cobalamin, and are commercially cultivated for industrial vitamin $\text{B}_{12}$ bio-fortification.
2. {Brevibacterium (B. linens): Surface smear cheese ripening bacterium.
3. (Standard LAB lack complete cobalamin synthetic pathways).

Step 3: Final Answer:
Hence, the bacterium that synthesizes vitamin B12 is Propionibacterium, corresponding to option (C).