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Title: COMPOSITION AND PHYSIOLOGICAL PROFILING OF SPROUT-ASSOCIATED MICROBIAL COMMUNITIES

Author
item MATOS, ANABELLE
item GARLAND, JAY - DYNAMAC CORP.
item FETT, WILLIAM

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: At least nineteen food poisoning outbreaks due to the consumption of sprouts contaminated with Salmonella and Escherichia coli O157:H7 have occurred in the past six years in the United States. Alfalfa, clover and mung bean sprouts have been implicated in most of these sprout-related outbreaks. We examined the similarity among microbial communities associated with various sprout types to assess the relative effects of a variety of factors, including different sprout types, sprout growing facilities, seed lots and inoculation with sprout-derived inocula, on the microbial community structure of sprouts. We found comparable number and types of microbes associated with the various sprout types tested. Our results demonstrated that differences among microbial communities from various sprout types are greater than differences among alfalfa and clover microbial communities grown in different sprout growing facilities or from different seed lots. Manipulation of various sprout-derived microbial communities inoculated on alfalfa seeds showed a strong inoculation effect on the resulting microbial communities on sprouts. This study provides critical information for the evaluation of effective biological control treatments on sprouts.

Technical Abstract: The native microflora of various types of sprouts, including alfalfa, clover, sunflower, mung beans, and broccoli were examined to assess the relative effects of various factors, including different sprout types, sprout growing facilities, seed lots and inoculation with sprout-derived inocula, on the microbial community structure of sprouts. Sprouts were sonicated for 7 min or hand shaken with glass beads for 2 min to recover native microflora from the surface. The resulting suspensions were diluted and plated. The sprout-associated microbial communities were characterized by examining density (log CFU/g), richness (e.g., number of types of bacteria), and diversity (e.g., microbial richness and evenness) of microorganisms culturable on tryptic soy agar plates at 30 deg C. The relative similarity in sprout-associated microbial communities was assessed using community-level physiological profiles (CLPP). We found aerobic plate ecounts associated with the sprout surfaces at an average of 7.96 +/- 0.91 log CFU per gram fresh weight of sprout tissue. No statistically significant differences in microbial richness or microbial diversity were observed among microbial communities from various sprout types, sprout growing facilities, or seed lots. CLPP analyses revealed that the microbial communities associated with alfalfa and clover sprouts are more similar than those of the other sprout types tested. Variability among sprout types was greater than any differences between microbial communities associated with alfalfa and clover sprouts from different sprout-growing facilities and seed lots. Additional studies will examine changes in the native microbial community structure of sprouts following the introduction of a potential biological control agent.