Mycobacterium tuberculosis colonies on LJ medium are dry, rough, raised, irregular colonies with a wrinkled surface, tenacious, difficult to emulsify, creamy white and buff-colored. (Rough, tough, buff). Mycobacterium bovis forms moist, smooth, flat, white colonies on LJ media that break-up easily when touched. Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition