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Identification and characterization of two high affinity aptamers specific for Salmonella Enteritidis

Zhang, Zilei, Liu, Danlei, Bai, Yalong, Cui, Yan, Wang, Dapeng, Shi, Xianming
Food control 2019 v.106 pp. 106719
Escherichia coli, Listeria monocytogenes, Salmonella Enteritidis, Staphylococcus aureus, aptasensors, bacteria, color, colorimetry, dissociation, food pathogens, high-throughput nucleotide sequencing, ligands, nucleotide aptamers, screening
DNA aptamers are promising candidates for bio-recognition assays due to their accumulation of bacterial cells. This feature can be used to identify specific pathogens in food samples. However, the conventional process of aptamer screening by randomly picking bacterial plate colonies for Sanger sequencing risks the elimination of superior sequences. In this study, we screened and evaluated all aptamers that were targeted to Salmonella Enteritidis (S. Enteritidis). After 13 rounds of selection we obtained 77,296 unique sequences from a total of 3,225,931 sequences using Next Generation Sequencing. We identified two high affinity aptamers that possessed dissociation constants of 43.8 and 56.2 nM. In addition, these two aptamers showed low binding activity to other foodborne bacterial isolates including Staphylococcus aureus, Listeria monocytogenes and Escherichia coli. Furthermore, by incorporation of AuNP-based colorimetric aptasensor, both aptamers showed alterations in color in proportion to the number of S. Enteritidis cells in the range of 104 to 105 copies. These aptamers are promising ligands for the specific recognition and capture of S. Enteritidis from clinical, environmental and food samples.