Antuo Hu1, Cancan Gao2, Zhaoxin Lu3, Fengxia Lu4, Liangyu Kong2, Xiaomei Bie5. 1. College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China. Electronic address: 2019208013@njau.edu.cn. 2. College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China. 3. College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China. Electronic address: fmb@njau.edu.cn. 4. College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China. Electronic address: lufengxia@njau.edu.cn. 5. College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China. Electronic address: bxm43@njau.edu.cn.
Abstract
AIMS: To identify the main spoilage bacterium on fresh-cut leafy vegetables and establish a multiplex PCR assay. METHODS AND RESULTS: Based on physiological-biochemical, molecular identification, and artificial contamination tests, the main bacterium to spoil fresh-cut leafy vegetables was identified as Exiguobacterium spp. and Exiguobacterium acetylicum. Comparative genomics showed that P401_RS0117025 and oxi_50,582,462 genes are specific to Exiguobacterium spp. and E. acetylicum. Based on this, three pairs of primer sets to EaG-291, EaS-2B, and Ea16S-12 genes were designed and used to develop a multiplex PCR assay, which exhibited 100% specificity among 16 Exiguobacterium and 10 non-Exiguobacterium strains. Finally, 84 fresh-cut leafy vegetable samples were analyzed by multiplex PCR assay and standard physiological-biochemical experiments, the results showed multiplex PCR assay reached a detection rate of 96%. CONCLUSIONS: The main spoilage bacterium was identified as Exiguobacterium spp. and E. acetylicum on fresh-cut leafy vegetables based on the novel specific genes explored in this study. SIGNIFICANCE AND IMPACT OF STUDY: A rapid, specific, and sensitive PCR assay was developed for the detection of Exiguobacterium spp. and E. acetylicum.
AIMS: To identify the main spoilage bacterium on fresh-cut leafy vegetables and establish a multiplex PCR assay. METHODS AND RESULTS: Based on physiological-biochemical, molecular identification, and artificial contamination tests, the main bacterium to spoil fresh-cut leafy vegetables was identified as Exiguobacterium spp. and Exiguobacterium acetylicum. Comparative genomics showed that P401_RS0117025 and oxi_50,582,462 genes are specific to Exiguobacterium spp. and E. acetylicum. Based on this, three pairs of primer sets to EaG-291, EaS-2B, and Ea16S-12 genes were designed and used to develop a multiplex PCR assay, which exhibited 100% specificity among 16 Exiguobacterium and 10 non-Exiguobacterium strains. Finally, 84 fresh-cut leafy vegetable samples were analyzed by multiplex PCR assay and standard physiological-biochemical experiments, the results showed multiplex PCR assay reached a detection rate of 96%. CONCLUSIONS: The main spoilage bacterium was identified as Exiguobacterium spp. and E. acetylicum on fresh-cut leafy vegetables based on the novel specific genes explored in this study. SIGNIFICANCE AND IMPACT OF STUDY: A rapid, specific, and sensitive PCR assay was developed for the detection of Exiguobacterium spp. and E. acetylicum.