Evaluation of the deletion of LAC1 and removal of G418 marker. Strains were grown five days on L-dopa medium at 30°C in dark. A. 1. KN99α, production of abundant black melanin pigment. 2. lac1Δ (negative control strain), showing no discernible pigment production causing white appearance of colonies. 3. lac1ΔG418R, white appearance of colonies indicates that LAC1 has been successfully deleted with the loxP-G418-loxP construct. 4. lac1ΔG418S, transient expression of Cre-recombinase, G418 construct was excised and the strain remained unable to produce melanin. B. PCR products using LAC1 specific primers #7 and #8 for 1. wild type LAC1, 2. lac1ΔG418R, and 3. lac1ΔG418S. Molecular weights listed to the left side of gel image.