Propionibacterium, a gram-positive, anaerobic, rod-shaped genus of bacteria, derives its name from its unique metabolism. These bacteria have the remarkable ability to synthesize propionic acid using unusual transcarboxylase enzymes. Propionibacteria primarily inhabit human skin, residing in and around sweat glands, sebaceous glands, and other skin areas. While they are virtually ubiquitous and usually harmless, they have been implicated in acne and other skin conditions. In ruminants, propionibacteria play a role in reducing nitrate to nontoxic nitrogen compounds. Beyond their commensal roles, members of the genus Propionibacterium are widely used in various applications, including the production of vitamin B12, tetrapyrrole compounds, propionic acid, and even in the probiotics and cheese industries. For instance, the strain Propionibacterium freudenreichii subsp. shermanii contributes to the creation of CO2 bubbles in cheesemaking, resulting in the characteristic “eyes” or round holes in certain cheeses