Abstract

This study included the isolation and diagnosis of Prototheca microorganism from milk samples of 80 Cows with clinical and subclinical mastitis from different areas in Mosul city , from October 2006 to May 2007 . Prototheca were identified using morphological, cultural and biochemical characteristics . The study showed that 16 samples ( 20%) were positive to Prototheca from total count included 14 (17.5%) P. zopfii and two isolates (2.5%) P. stagnora . The study show the ability of this microorganism to produce some virulance factors such as : Urease , Esterase , Lecithinase and Lipase . Results of antibiotic sensitivity test indicated that all isolates were resistant to Ampicillin , Amoxycillin , Cephalexin , Neomycin , Streptomycin and Tetracycline , while they showed different percentages of sensitivity to Gentamycin , Polymyxin B and Nystatin.