Abstract:Lactic acid bacteria are common microorganisms in the food industry and human intestinal flora，they can promote the synthesis of N-nitrosamines that are strong carcinogens，and the promotion mechanism is still unclear，which strongly restricts the improvement of fermented food safety and the promotion of probiotic products.The change trends of Lactobacillus plantarum（L.plantarum）6A in promoting N-nitrosodiethylamnie（NDEA）synthesis in different environments were investigated in this paper，and the crucial genes and forming pathways involved in the promotion were further investigated by transcriptome technology.The network of promotion mechanisms was constructed.The results showed that NDEA forced L.plantarum 6A to produce NDEA precursors and thus promote the synthesis of NDEA by up-regulating gene expressions of purine nucleotide synthesis/metabolism（key genes as purL，purK，purC，purB，and purA），riboflavin synthesis/metabolism（ribBA，ribH，and ribE），and two-component system pathways（dltD，dltB，and dltA），and the precursors included nitrogen-rich purines，riboflavin，and alanine.It might indirectly catalyze nitrosation through riboflavin synthesis/metabolism and two-component system pathways to accelerate the synthesis of NDEA.