TY - JOUR

T1 - Influence of food preservation parameters and associated microbiota on production rate, profile and stability of acylated homoserine lactones from food-derived Enterobacteriaceae

AU - Ravn Flodgaard, Lars

AU - Christensen, Allan Beck

AU - Molin, Søren

AU - Givskov, Michael

AU - Gram, Lone

N1 - Keywords: 4-Butyrolactone; Animals; Chromatography, Thin Layer; Enterobacteriaceae; Fish Products; Food Handling; Food Microbiology; Food Preservation; Hydrogen-Ion Concentration; Salmon; Temperature; Time Factors

PY - 2003

Y1 - 2003

N2 - Quorum-dependent regulation is mediated by N-acyl-L-homoserine lactones (AHLs) in several Gram-negative bacteria. The production of AHLs has typically been studied using pure bacteria cultures grown in nutrient-rich media at optimal temperature. AHLs are produced in several chill-stored foods by Gram-negative bacteria participating in spoilage. As part of our investigation of the role of AHLs in food quality, we studied the AHL production in two Enterobacteriaceae isolated from cold-smoked salmon under growth conditions typical of those found in cold-smoked salmon. We tested the influence of carbon source (glucose, sucrose, xylose, arabinose, mannose, mannitol and sorbitol), temperature (5 and 25 degrees C), salt concentration (0-7%), pH (6, 7 and 8) and co-existing lactic acid bacteria microflora on the AHL profile and production rate from Serratia proteamaculans strain B5a and Enterobacter agglomerans strain B6a. The two strains produced the same types of AHLs under all conditions tested. The specific AHL concentrations (moles/liter/OD(450)) changed slightly for both strains at the various conditions. S. proteamaculans strain B5a produced approximately 150 nM/OD(450) N-3-oxo-hexanoyl homoserine lactone (OHHL) and E. agglomerans strain B6a produced two major signals, OHHL and N-3-oxo-octanoyl homoserine lactone (OOHL) in a 1:9 ratio with a total concentration of approximately 3000 nM/OD(450). The AHL signal molecules became unstable with increasing pH (>7.5). In cold-smoked salmon, pH is approximately 6 and therefore only a low degree of pH-induced turnover is expected to occur in this product. Overall, our study demonstrates that food-derived Enterobacteriaceae produce AHLs of the same type and in the same magnitude when grown under food-relevant conditions as when grown in laboratory media at high temperature. Also, the AHLs produced in foods will be relatively stable and their regulatory impact lasting during storage.

AB - Quorum-dependent regulation is mediated by N-acyl-L-homoserine lactones (AHLs) in several Gram-negative bacteria. The production of AHLs has typically been studied using pure bacteria cultures grown in nutrient-rich media at optimal temperature. AHLs are produced in several chill-stored foods by Gram-negative bacteria participating in spoilage. As part of our investigation of the role of AHLs in food quality, we studied the AHL production in two Enterobacteriaceae isolated from cold-smoked salmon under growth conditions typical of those found in cold-smoked salmon. We tested the influence of carbon source (glucose, sucrose, xylose, arabinose, mannose, mannitol and sorbitol), temperature (5 and 25 degrees C), salt concentration (0-7%), pH (6, 7 and 8) and co-existing lactic acid bacteria microflora on the AHL profile and production rate from Serratia proteamaculans strain B5a and Enterobacter agglomerans strain B6a. The two strains produced the same types of AHLs under all conditions tested. The specific AHL concentrations (moles/liter/OD(450)) changed slightly for both strains at the various conditions. S. proteamaculans strain B5a produced approximately 150 nM/OD(450) N-3-oxo-hexanoyl homoserine lactone (OHHL) and E. agglomerans strain B6a produced two major signals, OHHL and N-3-oxo-octanoyl homoserine lactone (OOHL) in a 1:9 ratio with a total concentration of approximately 3000 nM/OD(450). The AHL signal molecules became unstable with increasing pH (>7.5). In cold-smoked salmon, pH is approximately 6 and therefore only a low degree of pH-induced turnover is expected to occur in this product. Overall, our study demonstrates that food-derived Enterobacteriaceae produce AHLs of the same type and in the same magnitude when grown under food-relevant conditions as when grown in laboratory media at high temperature. Also, the AHLs produced in foods will be relatively stable and their regulatory impact lasting during storage.

M3 - Journal article

C2 - 12781938

VL - 84

SP - 145

EP - 156

JO - International Journal of Food Microbiology

JF - International Journal of Food Microbiology

SN - 0168-1605

IS - 2

ER -