Fig. 3

Comparison of assays with BLA1 and BLA2 to the enzymatic method for quantification of L- and D-lactic acid. (a-c) Linear regression analysis (black dotted line) of the correlation between the enzymatic method and the application of BLA1 and BLA2. Linear regression analysis was performed to find the 95% prediction interval (grey area). The concentrations L-lactic acid (a) and total DL-lactic acid (b) were obtained by assaying supernatant samples of L. amylovorus fermentation collected at 72-hour. The concentrations of D-lactic acid (c) were estimated as described in Materials and methods using data obtained by assaying supernatant samples of L. amylovorus fermentation. Error bars represent standard deviations of two biological replicates. (d) Bland Altman comparison plot (n = 8), showing the correlation between concentrations of D-lactic acid in L. amylovorus fermentation samples, which were determined using biosensor-based assay and enzymatic method. The difference is plotted against average values, and the 95% limits of agreement (thick dashed lines) of the difference between the two methods of measurement are shown, as is the bias line (fine dashed lines)