Previous Article | Next Article 
Applied and Environmental Microbiology, June 2005, p. 3321-3330, Vol. 71, No. 6
0099-2240/05/$08.00+0 doi:10.1128/AEM.71.6.3321-3330.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Involvement of Bacterial Quorum-Sensing Signals in Spoilage of Bean Sprouts
Maria Rasch,1* Jens Bo Andersen,2 Kristian Fog Nielsen,3 Lars Ravn Flodgaard,1 Henrik Christensen,4 Michael Givskov,2 and Lone Gram1Danish Institute for Fisheries Research, Department of Seafood Research, Søltofts Plads, c/o Technical University of Denmark Bldg. 221, DK-2800 Kgs. Lyngby, Denmark,1 BioCentrum, Centre for Biomedical Microbiology, Technical University of Denmark Bldg. 301, DK-2800 Kgs. Lyngby, Denmark,2 BioCentrum, Centre for Microbial Biotechnology, Technical University of Denmark Bldg. 221, DK-2800 Kgs. Lyngby, Denmark,3 Department of Veterinary Pathobiology, The Royal Veterinary and Agricultural University, Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark4
Received 4 June 2004/ Accepted 3 January 2005
Bacterial communication signals, acylated homoserine lactones (AHLs), were extracted from samples of commercial bean sprouts undergoing soft-rot spoilage. Bean sprouts produced in the laboratory did not undergo soft-rot spoilage and did not contain AHLs or AHL-producing bacteria, although the bacterial population reached levels similar to those in the commercial sprouts, 108 to 109 CFU/g. AHL-producing bacteria (Enterobacteriaceae and pseudomonads) were isolated from commercial sprouts, and strains that were both proteolytic and pectinolytic were capable of causing soft-rot spoilage in bean sprouts. Thin-layer chromatography and liquid chromatography-high-resolution mass spectrometry revealed the presence of N-3-oxo-hexanoyl-L-homoserine lactone in spoiled bean sprouts and in extracts from pure cultures of bacteria. During normal spoilage, the pH of the sprouts increased due to proteolytic activity, and the higher pH probably facilitated the activity of pectate lyase. The AHL synthetase gene (I gene) from a spoilage Pectobacterium was cloned, sequenced, and inactivated in the parent strain. The predicted amino acid sequence showed 97% homology to HslI and CarI in Erwinia carotovora. Spoilage of laboratory bean sprouts inoculated with the AHL-negative mutant was delayed compared to sprouts inoculated with the wild type, and the AHL-negative mutant did not cause the pH to rise. Compared to the wild-type strain, the AHL-negative mutant had significantly reduced protease and pectinase activities and was negative in an iron chelation (siderophore) assay. This is the first study demonstrating AHL regulation of iron chelation in Enterobacteriaceae. The present study clearly demonstrates that the bacterial spoilage of some food products is influenced by quorum-sensing-regulated phenotypes, and understanding these processes may be useful in the development of novel food preservation additives that specifically block the quorum-sensing systems.
* Corresponding author. Mailing address: Danish Institute for Fisheries Research, Department of Seafood Research, Søltofts Plads, c/o Technical University of Denmark Bldg. 221, DK-2800 Kgs. Lyngby, Denmark. Phone: 45 45 25 49 27. Fax: 45 45 88 47 74. E-mail: mra{at}dfu.min.dk.
Applied and Environmental Microbiology, June 2005, p. 3321-3330, Vol. 71, No. 6
0099-2240/05/$08.00+0 doi:10.1128/AEM.71.6.3321-3330.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
This article has been cited by other articles:
-
Gori, K., Mortensen, H. D., Arneborg, N., Jespersen, L.
(2007). Ammonia Production and Its Possible Role as a Mediator of Communication for Debaryomyces hansenii and Other Cheese-Relevant Yeast Species. J DAIRY SCI
90: 5032-5041
[Abstract] [Full Text]
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»