Purpose: The purpose of this study was to investigate fecal indicators (coliforms and Escherichia coli), as well as foodborne pathogens (E. coli O157:H7, Salmonella spp., and Listeria monocytogenes) in irrigation water used for Napa cabbage cultivation.
Methods: A total of 111 samples, including stream water (n=60), groundwater (n=36), and water in ponds (n=15), were collected from five different regions of Korea where Napa cabbage is massively grown. Fecal indicators and foodborne pathogens in irrigation water were analyzed by biochemical methods.
Results: The numbers of coliform from stream water, water in ponds, and ground water were 1.96 to 4.96, 2.71 to 3.78, and 0 to 3.98 log MPN/100 ml, respectively. Enterococci were detected in 95% (57 of 60) of th stream water samples, 80% (12 of 15) of water from ponds, and 19% (7 of 36) of ground water samples and ranged from 0 to 4.00, from 0 to 2.00, and from 0 to 2.76 log MPN/100 ml, respectively. Additionally, 97% (58 of 60) of stream water, 93% (14 of 15) of water in ponds, and 22% (8 of 36) of ground water samples were observed being contaminated with E. coli. Only 0.9% (1 of 111) of the irrigation water samples was positive for L. monocytogenes.
Significance: Data from this study enables microbial risk assessment for irrigation water used in Napa cabbage cultivation.