Fig. 2

Comparison of the WT and AAT1-MT with respect to oxalic acid production based on bioassays, medium pH, DCW, and scleroglucan production. a Metabolic pathway schematic of AAT1-MT. Inactivation of AAT1 sequence is marked by cross, and the increased oxalic acid production is marked with a red background. b Chromatogram of oxalic acid produced by WT and AAT1-MT in liquid medium; peaks were detected at the retention time of 1.4 min. Oxalic acid produced by the mutants was distinctly increased in concentration when compared with that by the WT (peak nos. 1 = oxalic acid, 2 = ferulic acid, 5 = chlorogenic acid, 6 = cinnamic acid). c Bioassays of mutants in peanut leaves and controls strains. The lesion area created by the erosion of acid metabolites, which is mainly oxalic acid, showed bright brown color, which is marked by black circles. d Scleroglucan and oxalic acid production during bioreactor cultivation. Symbols: AAT1-MT scleroglucan concentration ( ×), WT scleroglucan concentration (▲), AAT1-MT oxalic acid concentration (■), WT oxalic acid concentration (◆). e The line chart of pH and DCW concentrations. Symbols: AAT1-MT DCW concentration ( ×), WT DCW concentration (▲), pH of WT (■), pH of AAT1-MT (◆). Each value represents the mean ± standard deviation of measurements from triplicate cultures