Biology · Microbes in Human Welfare · NEET
Alexander Fleming discovered penicillin. He first saw that a mould stopped bacteria from growing. But Fleming could not turn it into a usable medicine. Ernest Chain and Howard Florey came later and established its full potential as an effective antibiotic by purifying it. For NEET: Fleming = discovery, Chain and Florey = purification and mass use.
Because Fleming did not plan it. He was working on Staphylococci bacteria. He noticed a mould growing by accident in one of his unwashed culture plates. Around that mould, the bacteria could not grow. So the discovery happened by chance, not by a planned experiment. NCERT clearly calls it 'a chance discovery'.
Penicillin comes from a fungus (a mould), not a bacterium. The mould is Penicillium notatum. Fleming named the chemical Penicillin after this mould. This is a common trap: penicillin is produced by a fungus but it kills bacteria.
Fleming was working on Staphylococci bacteria. He noticed that Staphylococci could not grow around the mould. This told him the mould was releasing a chemical that stopped bacterial growth. That chemical was penicillin.
Fleming, Chain and Florey were awarded the Nobel Prize in 1945 for the discovery of penicillin. Remember all three names together with the year 1945. NEET has asked name-and-year type facts, so keep this exact.
Penicillin was extensively used to treat American soldiers wounded in World War II. This large-scale use became possible only after Chain and Florey purified it. This is a small factual detail NCERT mentions, useful for tricky MCQs.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes. NCERT states penicillin was the first antibiotic to be discovered. Other antibiotics were purified from other microbes only after penicillin.
Anti means 'against' and bio means 'life', so antibiotic means 'against life' of disease-causing microbes. For humans they are pro-life because they kill harmful microbes.
For NEET stick to what NCERT gives: Fleming named penicillin after Penicillium notatum. That is the species you must remember for the discovery story.
Fleming discovered penicillin by chance. Chain and Florey established its full potential and purified it into an effective medicine. All three won the Nobel Prize in 1945.
Microbes in Human Welfare regularly gives one MCQ, and 'first antibiotic', 'chance discovery', 'source mould' and 'Nobel Prize 1945' are direct one-liner facts examiners love to test.
