Microbes In Human Welfare

Penicillin, the first antibiotic to be discovered, was a chemical produced by the mould Penicillium notatum, observed by Alexander Fleming when he noticed that a Staphylococcus culture had been inhibited around a contaminating fungal growth. Its full potential as an effective antibiotic was later established by Ernest Chain and Howard Florey, and penicillin went on to save many lives during the Second World War, for which the three scientists shared a Nobel Prize. Streptococcus lactis is incorrect because it is a lactic acid bacterium associated with dairy fermentation, not the source of penicillin. Aspergillus niger is wrong because, although industrially important for producing citric acid, it is not the organism from which penicillin was first obtained. Saccharomyces cerevisiae is incorrect since it is brewer's and baker's yeast used in fermentation of bread and alcoholic beverages, not an antibiotic producer. As recorded in NCERT Class 12, Chapter 10 (Microbes in Human Welfare), antibiotics are chemicals produced by microbes that kill or retard the growth of other disease-causing microbes. As a historical and biological check, only Penicillium notatum matches Fleming's discovery of an anti-Staphylococcal chemical, confirming it as the correct organism.