Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This study concerned the production, purification and application of extracellular chitinase from Cellulosimicrobium cellulans strain 191. In shaken flasks the maximum yield of chitinase was 6.9 U/mL after 72 h of cultivation at 25 degrees C and 200 rpm. In a 5 L fermenter with 1.5 vvm aeration, the highest yield obtained was 4.19 U/mL after 168 h of fermentation at 25 degrees C and 200 rpm, and using 3 vvm, it was 4.38 U/mL after 144 h of fermentation. The chitinase (61 KDa) was purified about 6.65 times by Sepharose CL 4B 200 gel filtration with a yield of 46.61%. The purified enzyme was able to lyse the cell walls of some fungi and to form protoplasts.403623630Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)