Rapid and simple colorimetric method for the quantification of AI-2 produced from Salmonella Typhimurium.
The aim of this study was to evaluate the feasibility of Fe(III) ion reduction for the simple and rapid quantification of autoinducer-2 (AI-2) produced from bacteria using Salmonella Typhimurium as a model. Since the molecular structure of AI-2 is somewhat similar to ascorbic acid it was expected that AI-2 would also act as a reducing agent and reduce Fe(III) ions in the presence of 1,10-phenanthroline to form the colored [(o-phen)3 Fe(II)]SO4 ferroin complex that could be quantified colorimetrically. In support of this, colony rinses and cell free supernatants from cultures of all tested AI-2 producing strains, but not the AI-2 negative Sinorhizobium meliloti, formed a colored complex with a λmax of 510nm. The OD510 values of these culture supernatants or colony rinses were in broad agreement with the % activity observed in the same samples using the standard Vibrio harveyi bioluminescence assay for AI-2 detection, and with previously reported results. This methodology could potentially be developed as an alternative method for the simple and rapid quantification of AI-2 levels produced in bacterial cultures.
Department of Food Science and Technology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
Siriluck
S
Wattanavanitchakorn
Department of Food Science and Technology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. Electronic address: cheunjit.p@chula.ac.th.
Cheunjit
C
Prakitchaiwattana
Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
Patchanita
P
Thamyongkit
D001431:Bacteriological Techniques / Q000379:methods*; D002623:Chemistry Techniques, Analytical; D003124:Colorimetry / Q000379:methods*; D005290:Ferric Compounds / Q000378:metabolism; D006714:Homoserine / Q000031:analogs & derivatives* / Q000032:analysis; D007783:Lactones / Q000032:analysis*; D010084:Oxidation-Reduction; D010618:Phenanthrolines / Q000378:metabolism; D012486:Salmonella typhimurium / Q000378:metabolism*; D013053:Spectrophotometry / Q000379:methods
D005290:Ferric Compounds; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D010618:Phenanthrolines; D006714:Homoserine; C025205:1,10-phenanthroline
Autoinducer; Quorum sensing; Salmonella Typhimurium