FIG. 4.

Relative compositions of microbial communities as determined by sequence-specific labeling of oligonucleotide probes. The relative compositions of the microbial communities of the salads containing Norwegian lettuce and Spanish lettuce were determined by sequence-specific labeling of oligonucleotide probes. (A) Signals obtained with the different probes used before storage (BS) and after storage at 4 and 10°C. The bacteria were separated from the salad matrix either by washing the sample (W) or by treating the sample in a stomacher (S). Triplicate samples from a single bag were analyzed for each time. (B) Signal intensities for the different probes relative to the total signal intensity (addition of all of the signals) for each sample. Signal intensities were measured as pixel density with an 8-bit gray scale. The error bars are standard deviations based on three replicates of the experiment shown in panel A.