O-methyltransferase that catalyzes the conversion of macrocin to tylosin, the ultimate step of tylosin antibiotic biosynthesis. Also able to mediate the conversion of lactenocin to desmycosin. macrocin + S-adenosyl-L-methionine = H(+) + S-adenosyl-L-homocysteine + tylosin Optimum pH is 7.5-8.0. Antibiotic biosynthesis; tylosin biosynthesis. Homodimer. Belongs to the methyltransferase TylF/MycF family.