副干酪乳杆菌F50高密度发酵提升去除黄曲霉毒素能力及其非靶向代谢组学

High Density Fermentation of Lactobacillus paracasei F50 Enhances the Ability to Remove Aflatoxins and its Non Targeted Metabolomics

摘要:

副干酪乳杆菌在食品工业和安全控制中均有重要作用，为了节约设备空间，降低生产成本并提升应用价值进行高密度发酵。该研究利用低成本的糖蜜和脱油毛叶山桐子粕对副干酪乳杆菌F50进行高密度发酵，以菌种密度作为响应值对培养条件和培养基成分进行优化。结果表明，副干酪乳杆菌发酵最佳条件为接种量3.5%、培养环境pH值 6.7以及添加碳酸钙1.7%和脱油毛叶山桐子粕3.2 g/L油封发酵，最终菌种密度可以从7.3×108 CFU/mL提高到1.7×1010 CFU/mL，约为常规培养的23倍，黄曲霉毒素去除率从优化前18.15%提升到优化后48.17%。为了探究高密度培养后黄曲霉毒素去除率提高的原因，利用液相色谱-质谱联用仪（Liquid Chromatograph Mass Spectrometer，LC-MS）非靶向代谢组学技术对优化培养前后的副干酪乳杆菌上清液进行检测。结果表明，优化前后副干酪乳杆菌发酵液主要差异代谢物有535种，脂类、多肽、有机酸代谢物含量增加。多种氨基酸代谢通路显著表达，参与谷胱甘肽的生物合成。该研究可为副干酪乳杆菌高密度发酵和生物降毒研究提供一定的参考。

Abstract:

Lactobacillus paracasei holds a significant role in the food industry and safety control. To conserve equipment space, minimize production costs, and elevate its application value, high-density fermentation is implemented. In this particular study, low-cost molasses and deoiled Idesia polycarpa maxim were utilized as substrates for the high-density fermentation of Lactobacillus paracasei F50. The culture conditions and medium components were meticulously optimized, with the strain density serving as the primary response variable. The results of the study unveiled the optimal fermentation conditions for Lactobacillus paracasei, which included a 3.5% inoculum, a culture environment with a pH of 6.7, 1.7% calcium carbonate, and a 3.2 g/L defatted Idesia polycarpa meal for fermentation. The final strain density could be increased from 7.3×108 CFU/mL to 1.7×1010 CFU/mL, about 23 times that of conventional culture. The aflatoxin removal rate increased from 18.15% before optimization to 48.17% after optimization. To delve deeper into the reasons behind this improvement in aflatoxin removal rate following high-density culture, liquid chromatography-mass spectrometry (LC-MS) non-targeted metabolomics technology was utilized to analyze the supernatant of Lactobacillus paracasei before and after the optimized culture.The findings of this analysis revealed the presence of 535 primary differential metabolites in the Lactobacillus paracasei fermentation broth before and after optimization. Notably, there was an increase in the contents of lipids, peptides, and organic acid metabolites. Moreover, various amino acid metabolic pathways were found to be significantly expressed, contributing to glutathione biosynthesis.In conclusion, this study provides a valuable reference for the high-density fermentation of Lactobacillus paracasei and research into biological detoxification, offering insights into the optimization of fermentation conditions and the metabolic changes associated with enhanced aflatoxin removal rates.