Protein Chips for Detection of Salmonella spp. from Enrichment Culture

Abstract

Food pathogens are the cause of foodborne epidemics, therefore there is a need to detect the pathogens in food productions rapidly. A pre-enrichment culture followed by selective agar plating are standard detection methods. Molecular methods such as qPCR have provided a first rapid protocol for detection of pathogens within 24 h of enrichment culture. Biosensors also may provide a rapid tool to individuate a source of Salmonella contamination at early times of pre-enrichment culture. Forty mL of Salmonella spp. enrichment culture were processed by immunoseparation using the Pathatrix, as in AFNOR validated qPCR protocols. The Salmonella biosensor combined with immunoseparation showed a limit of detection of 100 bacteria/40 mL, with a 400 fold increase to previous results. qPCR analysis requires processing of bead-bound bacteria with lysis buffer and DNA clean up, with a limit of detection of 2 cfu/50 μL. Finally, a protein chip was developed and tested in screening and identification of 5 common pathogen species, Salmonella spp., E. coli, S. aureus, Campylobacter spp. and Listeria spp. The protein chip, with high specificity in species identification, is proposed to be integrated into a Lab-on-Chip system, for rapid and reproducible screening of Salmonella spp. and other pathogen species contaminating food productions.

Analytic Method on Characteristic Parameters of Bacteria in Water by Multiwavelength Transmission Spectroscopy

“…Each dilution solution (1 ml) drawn by the pipette and nutrient agar medium at 45°C was poured into the sterile plate. These plates were incubated at 37°C/24 h and CFU counted [13].…”

“…At present, the existing detection methods of the concentration and physical structure and compositional characteristics of bacteria, such as isolation and culture [5][6][7], immunology [8,9], nucleic acid hybridization [10], polymerase chain reaction [11,12], and protein-chip technology [13], provide precise results, but there are still some limitations existing such as complex operation and long analysis time. In order to realize rapid detection of bacteria, some spectroscopy techniques, such as fluorescence [14][15][16], infrared [17][18][19], and Raman [20][21][22][23], have also been used for the determination of characteristic parameters of bacteria.…”

Fluorescence-Free Biosensor Methods in Detection of Food Pathogens with a Special Focus on Listeria monocytogenes

“…International regulations for ready-to-eat foods ask for corrective actions in the presence of L. monocytogenes: the bacteria count should be lower than 0.04 CFU g −1 for food that supports the growth of the microorganism, and 100 CFU·g −1 for food not supporting the survival. It is necessary to determinate absence of L. monocytogenes in foods destined to infants [ 1 , 2 , 3 , 4 ]. Microbiological criteria for L. monocytogenes in food safety are based on microbiology laboratory culture methods.…”

PHB Production in Biofermentors Assisted through Biosensor Applications

“…Biosensors for whole-cell bacterial detection have been recently reviewed [32][33][34][35]. Various detection systems have been applied in bacteria quantification, from spectrophotometric detection, as Fourier Transformation-IR spectrometry (FTIR) and Reflectometric Interference Spectroscopy (RIfS), to Surface Enhanced Raman Spectroscopy (SERS) [36], to electrochemical biosensors, such as Alternate Current (AC) susceptometry measuring the magnetic field, suitable for bacteria concentration evaluation, to impedance-based systems, as electrochemical impedance spectroscopy (EIS) [34,36].…”