title: Rapid detection of E. coli O157:H7 on turnip greens using a modified gold biosensor combined with light microscopic imaging system.
abstract: This research aims to demonstrate the feasibility of a modified gold biosensor to detect E. coli O157:H7 in leafy turnip greens. The gold biosensor was modified with dithiobis-succinimidyl propionate (DSP) and/or protein A or G. The gold biosensor modified with DSP (Gold-DSP) was combined with a light microscopic imaging system (LMIS). The optimal concentration and specificity of anti-E. coli O15 polyclonal antibodies (pAbs) on the biosensor were determined. The reliability of Gold-DSP biosensor was investigated by determining the sensitivity, specificity, and limit of detection (LOD) of the Gold-DSP combined with LMIS. The Gold-DSP combined with LMIS was applied to turnip greens for E. coli O157:H7 detection. The modification of Gold biosensor with DSP significantly increased the detected number of E. coli O157:H7. The specificity of pAbs was sufficient to react with target E. coli O157:H7 among the tested bacterial culture. The optimum concentration of pAbs was determined as 200 μg/mL. The sensitivity, specificity, and LOD of Gold-DSP combined with LMIS were determined as 100%, 90%, and 10(3)  CFU/25 mm(2) , respectively. When applied to turnip greens, the Gold-DSP combined with LMIS could detect 2641 ± 394 and 15383 ± 3853 cell/mm(2)  with the initial concentrations of 10(1)  and 10(2)  CFU/25 g turnip greens, respectively, after 10 h-enrichment. Overall, this research suggested that the Gold-DSP combined with LMIS could be used to detect E. coli O157:H7 on turnip greens qualitatively and quantitatively.
authors.affiliation: Materials Research and Education Center, Auburn Univ, 275 Wilmore Labs, Auburn, AL 36830, USA.
authors.forename: Mi-Kyung
authors.initials: MK
authors.lastname: Park
authors.forename: Jun-Hyun
authors.initials: JH
authors.lastname: Oh
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D029688:Brassica napus / Q000382:microbiology*; D015169:Colony Count, Microbial; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology / Q000379:methods*; D006046:Gold / Q000737:chemistry; D008859:Microscopy, Polarization / Q000379:methods*; D018515:Plant Leaves / Q000382:microbiology; D015203:Reproducibility of Results
chemical_list: D006046:Gold