College of Light Industry and Food Engineering, Guangxi University, Nanning, 530004, China.
Curr Microbiol. 2024 Sep 3;81(10):342. doi: 10.1007/s00284-024-03777-8.
Exopolysaccharides (EPS) are natural macromolecular carbohydrates with good functional activity and physiological activities, which can be utilized as an emulsifier, viscosity enhancer, stabilizer, gelling agent, and water retention agent in a wide range of food products. In this study, the whole genome of Bacillus amyloliquefaciens D189, an EPS-producing bacteria, was sequenced. The result showed that D189 contains a single, circular chromosome of 3,963,356 bp with an average GC content of 45.74% and 3996 coding genes. The gene annotation results showed that D189 is a potentially safe strain and confirmed to be safe associated with hemolytic assay, and antibiotic resistance test. Meanwhile, D189 genome possessed 240 genes related to carbohydrate metabolism. More importantly, D189 could transport 9 sugars and contained a complete biosynthetic pathway for 8 nucleotide sugars. Based on the validation experiments, strain D189 could metabolize 8 sugars (glucose, sucrose, trehalose, fructose, cellobiose, maltose, mannitol, and N-acetyl-D-glucosamine) to produce EPS, with the highest yield of 1.212 g/L when sucrose was the carbon source. Therefore, the whole genome sequencing preliminarily elucidated the physiological mechanism of EPS, providing several pathways for engineering D189 to further enhance the yield of EPS.
胞外多糖（EPS）是具有良好功能活性和生理活性的天然高分子碳水化合物，可广泛应用于食品产品中作为乳化剂、增稠剂、稳定剂、胶凝剂和保水剂。本研究对产 EPS 的解淀粉芽孢杆菌 D189 进行了全基因组测序。结果表明，D189 含有一条大小为 3963356bp 的单链环状染色体，GC 含量为 45.74%，编码 3996 个基因。基因注释结果表明，D189 是一株具有潜在安全性的菌株，溶血试验和抗生素耐药性试验结果证实其与安全性相关。同时，D189 基因组中存在 240 个与碳水化合物代谢相关的基因。更为重要的是，D189 可以转运 9 种糖，并且含有完整的 8 种核苷酸糖的生物合成途径。基于验证实验，菌株 D189 可以代谢 8 种糖（葡萄糖、蔗糖、海藻糖、果糖、纤维二糖、麦芽糖、甘露醇和 N-乙酰-D-葡萄糖胺）来生产 EPS，当以蔗糖为碳源时，其产量最高可达 1.212g/L。因此，全基因组测序初步阐明了 EPS 的生理机制，为进一步提高 D189 产量的 EPS 工程提供了几种途径。
