Rhodamine B-Olive Oil Plate Assay

The BMMY–rhodamine B-olive oil plates were prepared according to previously described methods [68 (link)], using BMMY solid medium that contained 8 mg of rhodamine B and 10 mL of emulsified olive oil (Olivoila, Shanghai, China) per liter. Only active colonies can catalyze the hydrolysis reaction of olive oil and display clear red halos after a few days of growth. Moreover, the size of the halo correlates with the activity of recombinants [68 (link)]. In the stage, 14 colonies for each recombinant protein were first selected from the minimal dextrose solid Petri dishes and then transferred onto such plates for phenotype verification. Notably, the recombinant strain GS115/pGAP815α/wt–TLL and GS115 were used as positive and negative controls, respectively.