Application of a Rapid Method for Detecting V ibrio Parahaemolyticus in Seafood

Development of enhanced selective media for detection of Vibrio parahaemolyticus in oysters

This study was undertaken to develop enhanced selective media for detection of Vibrio parahaemolyticus in oysters. Primarily, tryptic soy agar (TSA) was supplemented with 4.5-5% NaCl, 0.1-0.5% oxgall, and/or 1-2% sodium citrate, and adjusted to pH 8-9. A total of 21 Vibrio spp., 24 indicators, and 26 food-borne isolates were streaked on the modified media, followed by 24 h of incubation at 37 °C. While all the indicators and isolates failed to grow on TSA containing 5% NaCl, 0.5% oxgall, and 2% sodium citrate (TSA_OSS1; pH 9), V. parahaemolyticus was culturable on this selective medium. Particularly, the ability of TSA_OSS1 to quantify V. parahaemolyticus in oysters was superior to thiosulphate citrate bile salts sucrose (TCBS) agar. V. parahaemolyticus distinctly produced its white-yellowish, round, and edge-pointed colony on TSA_OSS1. TSAO_SS1 with high selectivity potentials over TCBS may be a promising alternative for detection of V. parahaemolyticus in seafoods or natural reservoirs.

Supplementary Information

The online version contains supplementary material available at (10.1007/s10068-021-00877-0).

Rapid and selective recognition of Vibrio parahaemolyticus assisted by perfluorinated alkoxysilane modified molecularly imprinted polymer film

Molecular imprinting technology offers a means of tailor-made materials with high affinity and selectivity for certain analysts. However, the recognition and separation of specific bacteria in complex matrices are still challenging. Herein, a bacteria-imprinted polydimethylsiloxane (PDMS) film was facilely prepared and modified with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (POTS). Employing Vibrio parahaemolyticus as a model bacterium, the imprinted surface exhibited three-dimensionality cavities with mean size of 1000 × 800 nm in square and 100 nm in depth. After incubation for 2 h with 6 × 10⁷ CFU mL⁻¹ of V. parahaemolyticus, the imprinted polymer film can reach a 62.9% capture efficiency. Furthermore, the imprinted POTS-modified PDMS film based solid phase extraction combined with polymerase chain reaction and agarose gel electrophoresis allows for detecting 10⁴ CFU mL⁻¹ with excellent selectivity in fresh oyster samples. As a result, the developed selective sample pretreatment method using molecular imprinting technology provides a promising platform for separation, identification, and analysis of pathogens.

Molecular imprinting technology offers a means of tailor-made materials with high affinity and selectivity for certain analysts.

Surface-enhanced Raman spectroscopic single step detection of Vibrio parahaemolyticus using gold coated polydimethylsiloxane as the active substrate and aptamer modified gold nanoparticles

A method is described for single-step detection of V. parahaemolyticus in seafood via aptamer-based SERS. A gold-coated polydimethylsiloxane (PDMS) film was used for the enhancement of Raman scattering. The Raman reporter 4-mercaptobenzoic acid was linked to aptamer modified gold nanoparticles (AuNPs) served as a signalling probe. The negatively charged signalling probe was assembled onto the cysteamine-modified Au-PDMS film through electrostatic adsorption. On addition of V. parahaemolyticus, it will be bound by the aptamer as a biorecognition element, and this leads to the dissociation of the signalling probe from the Au-PDMS film. Hence, the Raman signal (at 1592 cm^-1) decreases. The assay has a wide linear response that covers the 1.2 × 10² to 1.2 × 10⁶ cfu·mL^-1 V. parahaemolyticus concentration range. The detection limit is 12 cfu·mL^-1. The method was successfully applied to the determination of V. parahaemolyticus in oyster and salmon samples. Graphical abstract Schematic presentation of a surface-enhanced Raman spectroscopic method for single step detection of Vibrio parahaemolyticus using gold coated polydimethylsiloxane as the active substrate and aptamer modified gold nanoparticles. This solid substrate simplified the analysis procedures and enhanced the sensitivity.

Colorimetric Immunoassay for Rapid Detection of Vibrio parahemolyticus Based on Mn2+ Mediates the Assembly of Gold Nanoparticles

Vibrio parahemolyticus ( V. parahemolyticus) is an important food-borne pathogen that causes food poisoning and acute gastroenteritis in humans. Herein, a novel colorimetric immunoassay was presented for rapid detection of V. parahemolyticus using gold nanoparticles (18.1 nm diameter) as chromogenic substrate, whose combination of a magnetic bead-based sandwich immunoassay and an optical sensing system via Mn²⁺ ions mediated aggregation of gold nanoparticles. MnO₂ nanoparticles coated with polyclonal IgG antibodies (7.8 nm diameter) are used to recognize the target and can be etched to generate manganese ions by ascorbic acid. A color change ranging from red to purple to blue can be easily discerned by bare eye, corresponding to V. parahemolyticus concentration in the range between 10 and 10⁶ cfu·mL^-1. The proposed method possesses high specificity with a limit of detection of 10 cfu·mL^-1 and was successfully applied to determination of V. parahemolyticus in oyster samples without pre-enrichment. In our perception, it shows promise in rapid instrumental and on-site visual detection of V. parahemolyticus.

Temperature Effect Study on Growth and Survival of PathogenicVibrio parahaemolyticusin Jinjiang Oyster(Crassostrea rivularis)with Rapid Count Method

The growth ofVibrio parahaemolyticus (V. parahaemolyticus)in oysters during postharvest storage increases the possibility of its infection in humans. In this work, to investigate the growth or survival profiles in different media, pathogenicV. parahaemolyticusin APW, Jinjiang oyster (JO,Crassostrea rivularis) slurry, and live JO were studied under different temperatures. All the strain populations were counted through our double-layer agar plate (DLAP) method. In APW, the pathogenicV. parahaemolyticusshowed continuous growth under 15, 25, and 35°C, while a decline in behavior was displayed under 5°C. The similar survival trend of pathogenicV. parahaemolyticusin JO slurry and live JO was observed under 5, 25, and 35°C, except the delayed growth or decline profile compared to APW. Under 15°C, they displayed decline and growth profile in JO slurry and live JO, respectively. These results indicate the different sensitivity of pathogenicV. parahaemolyticusin these matrices to temperature variation. Furthermore, nonpathogenicV. parahaemolyticusdisplayed little difference in survival profiles when inoculated in live JO under corresponding temperatures. The results indicate that inhibition or promotion effect could be regulated under different storage temperature for both pathogenic and nonpathogenic strains. Besides, the DLAP method showed the obvious quickness and efficiency during the bacteria count.

Sensitive detection of multiple pathogens using a single DNA probe

A simple but promising electrochemical DNA nanosensor was designed, constructed and applied to differentiate a few food-borne pathogens. The DNA probe was initially designed to have a complementary region in Vibrio parahaemolyticus (VP) genome and to make different hybridization patterns with other selected pathogens. The sensor was based on a screen printed carbon electrode (SPCE) modified with polylactide-stabilized gold nanoparticles (PLA-AuNPs) and methylene blue (MB) was employed as the redox indicator binding better to single-stranded DNA. The immobilization and hybridization events were assessed using differential pulse voltammetry (DPV). The fabricated biosensor was able to specifically distinguish complementary, non-complementary and mismatched oligonucleotides. DNA was measured in the range of 2.0×10(-9)-2.0×10(-13)M with a detection limit of 5.3×10(-12)M. The relative standard deviation for 6 replications of DPV measurement of 0.2µM complementary DNA was 4.88%. The fabricated DNA biosensor was considered stable and portable as indicated by a recovery of more than 80% after a storage period of 6 months at 4-45°C. Cross-reactivity studies against various food-borne pathogens showed a reliably sensitive detection of VP.