Effects of Surface Morphologies of Fresh Produce on the Performance of Phage-Based Magnetoelastic Biosensors

Abstract

This study investigated the effects of different surface morphologies on the performance of phage-based magnetoelastic (ME) biosensors for Salmonella Typhimurium detection on selected fresh produce. The ME biosensor is composed of an ME resonator platform and filamentous E2 phage for the specific recognition of S. Typhimurium. After SEM observation of the surface morphologies of tomatoes and spinach (adaxial/abaxial), S. Typhimurium was inoculated serially onto the surfaces to examine the attachment and distribution of bacterial cells on the surfaces. Finally, the linearity and detection limit of the ME biosensors detecting S. Typhimurium on food surfaces were tested. The morphologies of tomato and spinach surfaces were obviously different due to the existence of stomata and the differences in roughness and curvature. However, there were no obvious differences in attachment and distribution of bacterial cells on the surfaces. The resonant frequency shifts of measurement sensors increased linearly with an increase in the concentration of S. Typhimurium in contrast to relatively constant and negligible shifts of control sensors. Detection limit of the ME biosensor method was determined to be 1.87 log CFU/cm 2 for the tomatoes, 1.72 log CFU/cm 2 for the adaxial surface of spinach, and 2.16 log CFU/cm 2 for the abaxial surface of spinach.

Novel Approach of a Phage-Based Magnetoelastic Biosensor for the Detection of Salmonella enterica serovar Typhimurium in Soil

“…ME platforms were fabricated from METGLAS 2826MB alloy ribbon (Honeywell Inc., USA). The ribbon was diced into rectangular-shaped platforms with a size of 0.028 mm × 0.2 mm × 1 mm, using a computer controlled automatic micro-dicing saw (MPE Inc., USA) following the procedures mentioned in previous studies [17,18].…”

“…The binding of E2 phage and S. Typhimurium increases the total mass on the ME sensor, so the vibration of the ME sensor is decreased, resulting in a resonant frequency shift. The resonant frequency shift is directly proportional to the number of S. Typhimurium bound to the ME sensor; therefore, the target bacteria can be identified and quantified from the resonant frequency shifts of the ME sensor [17,18].…”

“…In the last decade, there has been more than several hundred publications describing on-site and rapid performance of the ME biosensor. Previous studies [12,14,15,17,18] showed the possibility and practicability of the ME biosensor as an on-site and rapid detection method, using cantaloupes, spinach, tomatoes, and milk. Furthermore, the ME biosensor method has been evaluated and validated objectively by comparison with a TaqMan-based quantitative PCR in the aspects of excellent selectivity, repeatability, simple assay protocol, minimal skilled operator, fast assay time, portability, and cost-effectiveness [20,21].…”

Detection of methicillin-resistant Staphylococcus aureus using novel lytic phage-based magnetoelastic biosensors

“…Furthermore, the LOD of the ME biosensor method was approximately 2 log lower than that of the SPR method using the same lytic phage (p < 0.05). In addition, previous studies [16,17,27,28] already demonstrated that the ME biosensor method was relatively fast (several minutes), cost effective (pennies/sensor), and simple in operation compared with other rapid detection methods such as real-time PCR and SPR. Since this study focused on the first application of a lytic phage on the ME biosensor method as a new bio-recognition element, the ME biosensors was applied to pure culture of MRSA instead of real food samples.…”

“…The ME biosensor method has been used successfully for the on-site detection of Salmonella and Bacillus anthracis spores [14][15][16][17]. However, to our knowledge, the ME biosensor method has so far not been used for MRSA detection.…”