For transformation of Synechocystis why do you first plate y

For transformation of Synechocystis, why do you first plate your transformant mixture on a filter on a BG-11 plate with glucose, and the next day the TA transfers the filter with cells to a plate that contains kanamycin (rather than plating directly on kanamycin)

Solution

Antibiotics like kanamycin are used to study knock-out expression of the genes and for evaluating positive genomic expression. Direct placement of the transformant mixture on kanamycin will result in degradation of the proteins which help in the survival of Synechocystis.