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.B族维生素（B vitamins, VBs）是一类必需的微量营养素，但其在各类自然生境中的微生物合成过程仍未得到充分解析。我们分析了126931个宏基因组组装基因组（metagenome-assembled genomes, MAGs），以绘制B族维生素产生菌的分布图谱，并构建了包含87个B族维生素合成基因的数据库，同时鉴定出不依赖外源性B族维生素的产生菌及其环境驱动因子。土壤与淡水生境中，VB1、VB2、VB7、VB9及VB12产生菌的多样性最为丰富，而海洋生境中的此类菌株则相对较少。VB5的合成能力极为罕见，VB3与VB6的合成能力也较为有限。γ-变形菌纲（Gammaproteobacteria）是高产B族维生素的类群，可合成多达8种B族维生素类型。土壤硫含量与电导率可显著提升B族维生素的合成潜力，为有益微生物与土壤健康改善之间建立了关联。我们进一步在库克不动杆菌（Acinetobacter kookii）中验证了VB3与VB7的合成过程，佐证了我们的预测框架。由于所鉴定的产生菌同时涵盖有益与致病类群，因此需开展审慎的评估工作。本研究构建了一套可靠的基因数据库，为农业与生物技术领域优化微生物B族维生素合成提供了重要基础。