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Nanosensors for Food Contaminant Detection
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
Heera Jayan, L. Bhavani Devi, C. Anandharamakrishnan
The cholera toxin is produced by the bacterium Vibrio cholerae. The toxin is present in contaminated food and water, which causes watery diarrhea when consumed. The cholera toxin binds to the GM1 ganglioside receptor on the surface of mucosal cells when it reaches the small intestine. So GM1 ganglioside can be used as a receptor in the development of a sensor for the detection of Vibrio cholerae (Tark et al., 2010). Ganglioside-incorporated nanodiscs can be used to functionalize microcantilever and the changes in the vertical deflection are measured through position sensitive detector (PSD). A stable receptor layer has been created without compromising the bioactivity of the membrane protein by the use of nanodiscs for the immobilization of GM1 ganglioside on the microcantilever surface.
Catabolite Regulation of the Main Metabolism
Published in Kazuyuki Shimizu, Metabolic Regulation and Metabolic Engineering for Biofuel and Biochemical Production, 2017
Cholera is an acute intestinal infection caused by the Gram-negative bacterium Vibrio cholerae, where it is still a major global burden as outbreaks frequently occur in developing countries (Sack et al. 2006). V cholerae is acquired by ingestion of contaminated food or water, and once acquired it colonizes and multiplies in the human small intestine. The induction of cholera toxin after colonization of the small intestine causes the production of a secretory diarrhea, or rice-water stool (Lee et al. 1999, Reidl and Klose 2002). V. cholerae survives as it passes between the human small intestine and aquatic environment, where it faces dramatic change in its living environment with much less available nutrient. Therefore, V. cholerae may prepare for such harsh condition prior to exiting the host at the late stage of infection (Schild et al. 2007). The surviving strategies may be to form biofilms (Watnick and Kolter 2000) to produce large amounts of polyphosphate (Ogawa et al. 2000, Jahid et al. 2006), and to accumulate glycogen during human infection (Bourassa and Camilli 2009).
Nanosensors in Food Safety: Current Status, Role, and Future Perspectives
Published in Deepak Kumar Verma, Megh R. Goyal, Hafiz Ansar Rasul Suleria, Nanotechnology and Nanomaterial Applications in Food, Health, and Biomedical Sciences, 2019
Cholera toxin (CT), a hexameric protein complex produced through Vibrio cholera. The infection causes massive, watery diarrhea in humans. It consists of single, enzymatically active A subunit (CTA, 27 kDa), linked non-covalently with pentameric core of five identical receptor-binding B subunits (CT-B, 58 kDa). The activation of adenylatecyclase is responsible for their biological activity. Nowadays based on their toxicity the development of highly selective and sensitive methods for the detection of cholera toxin is urgently required. Viswanathan et al.89 fabricated an electrochemical immunosensor based on Nafion-supported multiwalled CNTs. The surface of CNTs has been coated with an anti-CT-B subunit monoclonal antibody with thiol compounds that are encapsulated in liposomes. The sandwich-type assay was utilized for the detection through the binding of functionalized ganglioside liposome with anti-CT antibody-toxin complex. An adsorptive square-wave stripping voltammetry method was used for measurement of potassium ferrocyanide molecules released from liposomes bound onto working electrode. In another study, ganglioside lipid bilayer was used for detection of CT by tethered GNPs. This method was compared with other fluorescent immunoassays and results showed 100 times more sensitive detection. Furthermore, Schofield et al.77 developed a colorimetric method for the CT detection. They used GNPs (16 nm) on which the thiolated-lactose derivative self-assembled and aggregated followed by the binding of the CT-B subunit. The analysis was performed on the basis of colorimetric shift from red to purple. This colorimetric nanosensing device displayed limit of detection of 3 μg/mL.
Toxigenic V. cholerae, V. parahaemolyticus, and V. vulnificus in oysters from the Gulf of Mexico and sold in Mexico City
Published in International Journal of Environmental Health Research, 2019
Carlos L. Fernández-Rendón, Guadalupe Barrera-Escorcia, Irma Wong-Chang, Alfonso Vázquez Botello, Bruno Gómez-Gil, Marcial Leonardo Lizárraga-Partida
Several factors are associated with the virulence of these pathogens. V. cholerae synthesizes a thermostable enterotoxin and several strains produce extracellular enzymes, cytolysins, cytotoxins, hemolysins, capsular polysaccharide, and hemagglutinins (Cabrera-Rodríguez et al. 2008). This species presents around 200 serogroups, of which O1 and O139 produce cholera toxin and causes epidemic cases in the world (Chaudhuri and Chatterjee 2009). Recently the cholix toxin was described (Purdy et al. 2010). In the case of V. parahaemolyticus, the main virulence factors are linked with hemolysin toxins: thermostable direct hemolysin, a pore-forming protein, and related hemolysin that plays a significant role in precipitating the disease (López-Hernández et al. 2015a). Virulence factors in V. vulnificus are associated with capsular polysaccharide, iron acquisition systems, type IV pili, several enzymes (such as proteases, elastase, hyaluronidase, lecithinase, phospholipases, mucinases, and metalloprotease), repeat-in-toxin, and hemolysin/cytolysin (VvhA), among others (Quiñones-Ramírez et al. 2010; Guerrero et al. 2015).