Hygromycin B is an aminoglycoside antibiotic produced by Streptomyces hygroscopicus that is routinely used as a selection agent for cells that contain hph or hyg Hygromycin resistant gene. Hygromycin B is thought to inhibit protein synthesis by strengthening the interaction of peptidyl-tRNA in the ribosomal acceptor (“A”) site thereby preventing translocation of by EF-2 (elongation Factor-2). Hygromycin B is effective on most bacteria, fungi and higher eukaryotes.