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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #314619

Title: Persistence and internalization of Salmonella on/in organic spinach sprout: exploring the contamination route

item DEV KUMAR, GOVINDARAJ - University Of Arizona
item Patel, Jitu
item RAVISHANKAR, SADHANA - University Of Arizona

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/17/2015
Publication Date: 7/25/2015
Citation: Dev Kumar, G., Patel, J.R., Ravishankar, S. 2015. Persistence and internalization of Salmonella on/in organic spinach sprout: exploring the contamination route. International Association for Food Protection. p.T7-03.

Interpretive Summary:

Technical Abstract: Purpose: The effects of contamination route, including seed and water, on the persistence and internalization of Salmonella in organic spinach cultivars- Lazio, Space, Emilia and Waitiki were studied. Methods: Seeds (1g) were contaminated with S. Newport using 10 ml of S. Newport-water suspension overnight. Contaminated water for germination was prepared by resuspending and diluting an overnight culture (40 ml) of S. Newport in sterile water. For testing both routes, contaminated or non-contaminated seeds were placed in a germination pouch, irrigated with sterile or contaminated water (15 ml water) and allowed to germinate in the dark at 25°C. After 5 days, germinated sprouts were analyzed for S. Newport population and internalization. Germinated sprouts were potted in soil, grown in a plant growth incubator for 4 weeks and leaves, stems and roots from 3 plants of each cultivar were sampled for Salmonella population by plating. Surface-sterilized plants were analyzed for internalized pathogen following enrichment. Potting soil and water runoff were sampled for Salmonella after 4 weeks of plant growth. Result: Contaminated seeds and irrigation water had S. Newport populations of 7.64±0.43 log CFU/g and 7.12±0.04 log CFU/ml, respectively. Sprouts germinated using contaminated water and seeds had S. Newport populations of 8.09±0.04 and 8.08±0.03 log CFU/g, respectively. Populations of S. Newport in leaves, stem and roots of spinach plants were as follows: contaminated seed- 2.82±1.69, 1.69±0.86, and 4.41±0.62 log CFU/ml; contaminated water- 3.56±0.90, 3.04±0.31, and 4.03±0.42 log CFU/ml of macerated tissue suspension, respectively. Internalization was observed in spinach grown from contaminated seed and in sprouts germinated with contaminated water. S. Newport populations of 2.82±0.70 log CFU/g and 1.76±0.46 log CFU/ml were recovered from soil and water runoff, respectively. Conclusion: These results indicate that contamination of spinach during germination can result in the persistence, internalization and environmental reintroduction of Salmonella.