Genes for Vitamin B Synthesis and Their Distribution in Microbial Producers

B vitamins (VBs) are essential micronutrients, yet their
microbial
production across natural habitats remains poorly understood. We analyzed
126,931 metagenome-assembled genomes to map the distribution of VB
producers and constructed a database of 87 VB synthesis genes, identifying
VB-independent producers and their environmental drivers. Soil and
freshwater habitats harbored the greatest diversity of VB1, VB2, VB7, VB9, and VB12 producers, whereas marine systems contained fewer. Biosynthetic
capacity was rare for VB5 and was limited for VB3 and VB6. Gammaproteobacteria are prolific producers,
synthesizing up to eight VB types. Soil sulfur content and conductivity
significantly enhanced VB production potential, linking beneficial
microbes to improved soil health. We further validated VB3 and VB7 synthesis in Acinetobacter kookii, supporting our predictive framework. Because the identified producers
include both beneficial and pathogenic taxa, careful evaluation is
required. This work provides a robust gene database and a foundation
for optimizing microbial VB production in agriculture and biotechnology.