this gradient determines a target image , whose center is the reservoir of antibiotic ( constituted by a paper disk containing 100 u of penicillin g ) and whose successive concentric zones are : a zone of slow bactericidal activity ( corresponding to high levels of penicillin g ) , a zone of maximal bactericidal activity ( corresponding to optimal levels of penicillin g ) , and a zone of overgrowth situated in front of the antibiotic wave .
C0030842
penicillin
C0030827
penicillin g