Scientists have been researching not only on vitamin properties but also its production, longing for facilitating human's life, as global demand on micronutrients boost, either to supply diet habits deficiency, or owing to expansion of application in industry. Microorganisms are capable of producing vitamins as metabolites, which are essential nutrients, working as cofactors or coenzymes in the energy production. So, microbial production has been researched for years. Few microorganisms may produce B-group vitamins, amongst them, Bacillus subtilis and Eremothecium ashbyii, whose vitamin is considered GRAS by U.S. Food and Drug Administration (FDA). Fermentative production has been replacing synthetic vitamin synthesis, leading to a better product, higher productivity and, most importantly, minimizing environmental impact. However, many factors affect each vitamin production since each one has its own physical and chemical characteristics. Thus, it is true that it is essential to overcome many drawbacks faced by the vitamin industry; most significantly, a process that is able to produce high amounts of vitamin per liter in a cheap substrate media so as to be an efficient cost-effective and competitive fermentation process to produce vitamin. Here, an overview of the microbial B-vitamin production is shown, seeing that it has been replacing the chemical production in most cases, because of the need for a clean, environmental-friendly process.