title: Characterization by transformation of an ampicillin-resistant mutant of pneumococcus.
mesh_terms: D000667:Ampicillin / Q000494:pharmacology*; D003433:Crosses, Genetic; D004269:DNA, Bacterial; D005787:Gene Frequency; D009154:Mutation; D010403:Penicillin Resistance; D013296:Streptococcus pneumoniae / Q000187:drug effects*; D013997:Time Factors; D014170:Transformation, Genetic
chemical_list: D004269:DNA, Bacterial; D000667:Ampicillin