Derivation
Penicillin is an antibiotic composed of Penicillium chrysogenum, a common fungal mold. Commonly found on food and in households, the penicillium mold produces a natural bacteria-killer known as penicillin. This production is not byproduct of a process, but an evolutionary advantage conferred to penicillium in competing against bacteria for food. Thus it is specifically targeted for the elimination of bacterial infections.
Breaking Down the Wall
Penicillin operates by dissolving the cell wall of bacteria, dispersing its cytoplasm and other cell systems. One essential component of the bacterial cell wall is transpeptidase, which accepts molecules of penicillin as a substrate attachment. The penicillin activates, preventing peptidoglycan reactions that strengthen links in the cell wall. This leads inevitably to cytolysis and cell death.
Resistance
While drug resistance, particularly strains increasingly immune to penicillin, has become big news recently, the development is long in coming. Since penicillium uses penicillin for the same purposes as humans, bacteria has already developed a set of defenses. Many bacteria produce penicillinase, which rots away the penicillin clinging to transpeptidase. This evolutionary combat highlights another method through which penicillin and its derivatives operate. Because bacteria has developed such defenses including double cell-walls which can't be fully dissolved, penicillin has evolved to work in concert with other chemicals such as aminoglycosides. Thus penicillin operates on several levels. In conjunction with aminoglycosides penicillin disrupts protein synthesis and even the reproduction of organelles within the bacterium.
Tags: cell wall