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Figure 1 | Plant Methods

Figure 1

From: A rapid biosensor-based method for quantification of free and glucose-conjugated salicylic acid

Figure 1

Standard curve optimization. (A) Effect of plant extract on SA-induced luminescence. SA standards were made with either LB or sid2-2 plant extract as the solvent. (B) Non-linearity of the SA-response curve. Data points were fitted with linear (blue) and third order polynomial (orange) best-fit lines. Note the lower R-squared value of the linear best-fit line. (C) A typical set of best-fit standard curves based on SA standards. The low SA concentration curve (orange) was fitted to standards of 0.8, 1.6, and 3.2 ng SA. The medium SA concentration curve (blue) was fitted to standards of 8, 16, 24, and 32 ng SA. The high SA concentration curve (green) was fitted to standards of 40, 48, 56, and 64 ng SA. (D) Diminishing response of the biosensor to increasing SA concentrations. (E) Effect of biosensor culture density on SA-induced luminescence. Biosensor cultures of OD600 = 0.6–0.8 were also tested and exhibited lower response to SA than OD600 = 0.4, but were omitted for clarity, as were error bars. Values indicate the average of three replicates with standard deviation (A-D only). Experiments were done three times with similar results.

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