|De La Riva-alvarez, S - Postgraduate College|
|Hernandez-anguiano, A - Postgraduate College|
|Corrales-garcia, J - University Of Chapingo|
|Zavaleta-mancera, H - Postgraduate College|
|Soto-hernandez, M - Postgraduate College|
Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2016
Publication Date: 10/1/2016
Citation: De La Riva-Alvarez, S.L., Hernandez-Anguiano, A.M., Corrales-Garcia, J.E., Zavaleta-Mancera, H.A., Soto-Hernandez, M., Patel, J.R. 2016. Response of tender cactus pads to Salmonella strains. Acta Horticulturae. 1141:207-212.
Interpretive Summary: Foodborne outbreaks associated with fresh produce have increased in recent years. Pre-harvest contamination of fresh produce via irrigation water, soil, or other animal vectors may be responsible for many of these outbreaks. We evaluated persistence of Salmonella on nopal plants (a type of cactus) when contaminated via irrigation water. The infiltration of Salmonella in nopal leaves induced a defense response which was observed by visual and color changes. Salmonella persisted on cactus leaves during the entire sampling period of 96 h; its persistence was affected by type of cactus cultivar. Further studies on effect of nopal cultivars on Salmonella persistence will be helpful to select cultivars resistant to contamination by Salmonella.
Technical Abstract: Tender cactus pads (cladodes) or nopalitos (Opuntia ficus-indica L) are an important vegetable in Mexico. They are often pre-trimmed, cut and packaged, and while usually consumed cooked, they may also be eaten raw in salads. Salmonella is an enteropathogenic bacterium that can adapt to adverse environmental conditions. Although it has been reported that Salmonella infected plants are asymptomatic; wilting, yellowing, biomass loss and a hypersensitive response (HR) have recently been demonstrated in plant tissues. The aim of this study was to investigate plant tissue response to different strains of S. enterica in two varieties of cactus as well as the persistence of Salmonella strains in the tissue. The top of pads (20-25 cm) of greenhouse-grown (17.3°C, 39.8 % RH) Milpa Alta and Atlixco varieties were inoculated with water (control) or 1 mL 8.0 log CFU of strains S. Typhimurium (N4), S. Javiana (N7) which were both isolated from nopalitos, and S. Typhimurium ATCC23564 (Sal 4). Cladodes (n=20) from each cactus variety were sampled and evaluated every 24 h for 5 days starting 6 h after inoculation for visual symptoms, color change and Salmonella persistence in the tissue. Color and appearance changed in longitudinal sections of pads of both varieties only in the area where the bacteria were infiltrated and this could be considered a hypersensitive response. All three Salmonella strains persisted during the sampling period of 96 h, the effect of Salmonella enterica serovars on its persistence was not significant. Salmonella persisted at lower levels on cladodes of Milpa Alta variety.