Detection and Characterization of β-Lactam Resistance inBacillus cereusPTCC 1015

In the present study, detection, isolation, and characterization of beta-lactamases from Bacillus cereus PTCC 1015 were investigated. B. cereus was inoculated in nutrient broth containing ampicillin (50 mg x ml(-1)) for 24 h (35 degrees C, 200 rpm). Activity measurements were carried out against ampicillin (0.1 mg x ml(-1)) and cephalexin (0.08 mg x ml(-1)) by a spectrophotometric method at different conditions (pH 6-10, temperatures 25-45 degrees C). Maximum penicillinase and cephalosporinase activity was observed at pH 7. The optimized temperatures for penicillinase and cephalosporinase activity were 30 and 40 degrees C, respectively. At the above conditions, maximum enzymatic activity was calculated as 0.89 +/- 0.014 and 0.037 +/- 0.001 units against ampicillin and cephalexin.