Detection of Exiguobacterium spp. and E. acetylicum on fresh-cut leafy vegetables by a multiplex PCR assay
Antuo Hu1, Cancan Gao1, Zhaoxin Lu1
1College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China.
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.
