Concomitant uptake of antimicrobials and Salmonella in soil and into lettuce following wastewater irrigation

Authors

J. Brett Sallach, University of Nebraska--LincolnFollow
Yuping Zhang, University of Nebraska--Lincoln
Laurie Hodges, University of Nebraska–LincolnFollow
Daniel D. Snow, University of Nebraska-LincolnFollow
Xu Li, University of Nebraska-LincolnFollow
Shannon L. Bartelt-Hunt, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

2-2015

Citation

Published in Environmental Pollution 197 (February 2015), pp. 269–277; doi:10.1016/j.envpol.2014.11.018

Comments

Copyright © 2014 Elsevier Ltd. Used by permission.

Abstract

The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and 125 ng/g fresh weight, respectively. Antimicrobial concentrations in lettuce decreased from the first to the third harvest suggesting that the plant growth rate may exceed antimicrobial uptake rates. Accumulation of antimicrobials was significantly different between cultivars demonstrating a subspecies level variation in uptake of antibiotics in lettuce.