Abstract Title
Impact of Soilless Substrate Type on Tulane Virus Persistence and Localization during Recirculating Deep Water Culture Hydroponic Cultivation of Leaf Lettuce
Presenter
Kristen Gibson, University of Arkansas System Division of AgricultureGayatri Dhulappanavar, University of Arkansas System Division of Agriculture
Co-Author(s)
Department of Food Science, Center for Food Safety, University of Arkansas System Division of Agriculture
Abstract Category
Food & Environmental Virology-I (Food)
Abstract
Food safety risks associated with hydroponic cultivation of leaf lettuce are not well characterized. The impact of soilless substrate type on the persistence and localization of a human norovirus surrogate, Tulane virus (TV), in recirculating deep water culture (DWC) systems during the cultivation of leaf lettuce was investigated. Nutrient solution (NS) in DWC systems containing 25-day old butterhead lettuce (cv. Rex) seedlings were inoculated with approximately 4 log PFU/mL of TV. TV concentration was determined in NS, soilless substrates (low-density foam [LDF], rockwool), roots, and leaves via virus plaque assay on post inoculation day 0 (lettuce seedling), 1, 3, 7, 14, and 21 (mature lettuce head). For cultivation in LDF, TV on day 0 was 2.66, 2.62, and 0.89 log in NS, LDF, and roots, respectively. Meanwhile, 1.83 and 1.97 log TV were detected in NS and rockwool, respectively, on day 0 of cultivation in rockwool, though no TV were detected in the roots. By day 21, TV declined to undetectable levels regardless of sample type. Moreover, TV was not detected in edible lettuce leaves at any time during the study. Additional experimental trials are ongoing. This study indicates a potential effect of soilless substrate type of TV localization during DWC of leaf lettuce. Results may be used to support substrate selection as a risk management practice during hydroponic lettuce cultivation. Although TV declined over the 21-day period, if not managed properly, this short-term persistence of enteric viruses indicates a potential cross-contamination risk during pre- and post-harvest handling.