Document Detail

Inhibition of Salmonella enterica by plant-associated pseudomonads in vitro and on sprouting alfalfa seed.
MedLine Citation:
PMID:  16629011     Owner:  NLM     Status:  MEDLINE    
Foodborne illness due to the consumption of contaminated raw or lightly cooked sprouts is a continuing food safety concern. In this study, we tested several plant-associated pseudomonads for their ability to inhibit the growth of Salmonella enterica both in vitro and in situ. An agar spot bioassay method was used with three different media. Only Pseudomonas fluorescens 2-79 produced clear zones of inhibition when tested against five serovars of S. enterica, and activity was dependent on media type and serovar. The antibiosis by derivative strains of P. fluorescens 2-79 defective in the production of phenazine-1-carboxylic acid and fluorescent siderophore was not reduced, indicating that these known antimicrobial metabolites were not responsible for the inhibition observed in our studies. However, mutants defective in the regulatory gene gacS (global antibiotic and cyanide control) were severely reduced in inhibitory activity. In tryptic soy broth, the control cultures of a cocktail of S. enterica strains reached approximately 10 log CFU/ml by 24 h but, when coinoculated with P. fluorescens 2-79, reached only approximately 5 log CFU/ml. The addition of P. fluorescens 2-79 to the seed soak water prior to the germination of alfalfa seed previously inoculated with a cocktail of S. enterica strains led to an average reduction of 5 log CFU/g at 6 days of sprouting without an adverse effect on sprout yield or appearance. Time course studies indicated that S. enterica outgrowth was controlled on days 1 through 6 of sprouting. Competitive exclusion as a potential food safety intervention for seed sprouts merits further study.
William F Fett
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of food protection     Volume:  69     ISSN:  0362-028X     ISO Abbreviation:  J. Food Prot.     Publication Date:  2006 Apr 
Date Detail:
Created Date:  2006-04-24     Completed Date:  2006-05-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7703944     Medline TA:  J Food Prot     Country:  United States    
Other Details:
Languages:  eng     Pagination:  719-28     Citation Subset:  IM    
Food Safety Intervention Technologies Research Unit, Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, Wyndmoor, Pennsylvania 19038, USA.
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MeSH Terms
Colony Count, Microbial
Consumer Product Safety
Culture Media / chemistry
Food Contamination
Food Microbiology*
Medicago sativa / microbiology*
Pest Control, Biological
Pseudomonadaceae / physiology
Pseudomonas fluorescens / physiology*
Salmonella enterica / growth & development*
Time Factors
Reg. No./Substance:
0/Culture Media

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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