There are billions and billions of incredibly diverse microorganisms within and around us. Putting numbers into perspective, the world’s human population is around 6 billion, and we can probably find the same number of bacteria in just one teaspoon of soil! It should therefore not be surprising that microbial populations influence almost every aspect of human and animal life. They influence the health of humans and animals, the foods we eat, and the deterioration of materials.

Autoinducer activity that detects bacterial-cell-signaling compounds is measured using instruments such as the Wallac Victor™ multilabel instrument from PerkinElmer.Microorganisms neve…

Figure 1 Schematic representation of molecules that function as autoinducers in bacterial quorum sensing: (A) acyl-homoserine lactones (AHLs), (B) boronated and non-boronated forms of AI-2, and (C) the amino acid sequence of oligopeptides (asterisk represents an isoprenyl modification).

Figure 3: Schematic representation of the proposed AI-3 signaling system in enterohemorrhagic E. coli O157:H7 (adapted from Reading and Sperandio, 2005).Figure 2: Schematic representation of the AI-2 responses and gene activation pathway observed in different bacteria (adapted from Vendeville et al., 2005).

Table 1: Production of AHLs by Gram-negative bacteria isolated from different food items. Modified from Gram et al. (2002)

Figure 4 Schematic representation of the AI-2 activity bioassay (note that negative controls must be included as needed)

Table 2: Inhibition of AI-2 activity by food extracts. Percent inhibition based on the positive control values. Modified from Lu et al. (2004)

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