50 Fun Facts About Microbiology

Which Dutch draper observed bacteria in 1676 and is called the 'Father of Microbiology'?

He never wrote a book, describing his 'animalcules' in chaotic letters to the Royal Society, which published them.

In which Dutch city did Van Leeuwenhoek live and work for most of his life?

He opened a draper's shop there in 1654 selling linen, yarn and ribbon before turning to lenses.

Robert Hooke's first recorded microscope observation, in 1665, was of what?

The Jesuit Athanasius Kircher may have beaten both Hooke and Van Leeuwenhoek, describing 'worms' in vinegar and milk in 1646.

Which Jesuit priest, writing on the plague in 1658, was likely the first person to see microbes?

He correctly said the disease was caused by microbes, though what he saw was probably blood cells; he was also a pioneer of the magic lantern.

Which 19th-century botanist founded bacteriology, describing Bacillus and drawing up the first bacterial taxonomy?

He also discovered the dormant spores some bacteria form; Pasteur and Koch were his contemporaries.

Louis Pasteur's famous flask experiments were designed to disprove which theory?

He used swan-neck flasks of fermentable liquid to show that no microbes appear 'without parents similar to themselves'.

Pasteur's technique of heating milk and wine to stop bacterial contamination is known as what?

He also developed vaccines for anthrax and rabies and rescued France's silk industry from a silkworm disease.

What was the name of the nine-year-old boy first treated with Pasteur's rabies vaccine in July 1885?

Jupille was treated that October, and four American children were among those who then travelled to Pasteur's lab.

Robert Koch's 1876 discovery of which bacterium is considered the birth of modern bacteriology?

He went on to identify the tuberculosis and cholera agents and won the 1905 Nobel Prize.

World TB Day is marked on 24 March because on that date in 1882 Koch announced what?

His later 'cure', tuberculin, failed as a treatment but became a diagnostic test after his death.

How many criteria make up Koch's postulates for linking a microbe to a disease?

They were formulated with Friedrich Loeffler in 1884 and refined by Koch in 1890; modified versions now exist for prions.

The shallow lidded dish used to culture microbes is named after which assistant of Robert Koch?

He made the final modifications to the design in 1887 at Berlin University.

Who first suggested agar, a jam-making staple, for culture media in Koch's lab in 1881?

She was working as a technician for her husband Walther Hesse; agar replaced gelatin, which melted at body temperature.

The Gram stain was developed in 1884 by a scientist of which nationality?

Hans Christian Gram devised it while working in the morgue of a Berlin city hospital.

In a Gram stain, Gram-positive bacteria retain which primary dye?

Their thick peptidoglycan wall holds the stain; Gram-negative cells lose it and take the pink counterstain.

Bacterial cell walls are made of which polymer, absent from archaea?

It is also called murein and is built from polysaccharide chains cross-linked by short peptides.

Spherical bacteria are called cocci. What are rod-shaped bacteria called?

'Bacillus' comes from the Latin for stick and 'coccus' from the Greek for grain or seed.

How long is a typical bacterial cell?

That is about a tenth the size of a eukaryotic cell; Mycoplasma, at 0.3 micrometres, is as small as the largest viruses.

Thiomargarita magnifica, the largest known bacterium, can reach what length?

It grows on sunken mangrove leaves in Guadeloupe and its discoverer at first took it for a fungus; the name means 'sulfur pearl'.

Under ideal conditions, roughly how quickly can E. coli reproduce?

It was discovered in 1885 by paediatrician Theodor Escherich and is the most studied prokaryote in the world.

Which pediatrician discovered E. coli in the faeces of healthy people in 1885?

The K-12 strain later became the workhorse of recombinant DNA work.

Roughly what fraction of environmental microbes can be grown in isolation in the lab?

That is why microbiologists now lean on DNA methods such as 16S rRNA sequencing to identify bacteria.

Which DNA sequence is the standard molecular tool for identifying bacteria?

The 18S gene plays a similar role for eukaryotes.

Who first classified archaea as separate from bacteria, in 1977?

At the time only the methanogens were known; the groups were dubbed Archaebacteria and Eubacteria.

Archaea have cell membranes built from what kind of lipids, unlike bacteria and eukaryotes?

They also have a unique motility structure, the archaellum, and many make methane.

The first virus ever identified, in the 1890s, infects which plant?

Dmitri Ivanovsky showed filtered sap stayed infectious in 1892 and Martinus Beijerinck named tobacco mosaic virus in 1898.

The word 'virus' comes from a Latin word meaning what?

'Virulent' dates to about 1400, and 'virus' meant an infectious agent as early as 1728, long before viruses were found.

Viruses that infect bacteria are called bacteriophages. What does the Greek root 'phagein' mean?

Félix d'Hérelle coined the name at the Pasteur Institute in 1917, two years after Frederick Twort's independent discovery in London.

Alexander Fleming discovered penicillin in 1928 from a mould of which genus?

The species was Penicillium rubens; Florey and Chain purified the drug in 1940 and shared the 1945 Nobel Prize with him.

Six years before penicillin, Fleming discovered which enzyme in his own nasal mucus?

He found it in 1922 along with a bacterium it destroyed, which he named Micrococcus lysodeikticus.

In 1847 Ignaz Semmelweis cut maternal deaths in Vienna from 18% to under 2% by insisting doctors do what?

He was mocked, committed to an asylum in 1865 and beaten by the guards there.

Joseph Lister pioneered antiseptic surgery in Glasgow using which chemical?

Modern-day phenol; he used it on instruments, sutures, wounds and surgeons' hands.

Before germ theory, diseases such as cholera were thought to be caused by what?

Girolamo Fracastoro had proposed transferable 'seeds' of disease as early as 1546, but Galen's miasma idea held sway for centuries.

Barry Marshall proved Helicobacter pylori causes gastritis by doing what?

He and Robin Warren described the ulcer-causing bug in 1983 and won the 2005 Nobel Prize in Physiology or Medicine.

Roughly how many bacterial cells live in the human body, according to a 2016 estimate?

That is about the same as the 30 to 40 trillion human cells, not the old 10-to-1 ratio.

Deinococcus radiodurans, listed by Guinness as the most radiation-resistant lifeform, has which nickname?

It was discovered in 1956 by Arthur Anderson in Oregon; the name means 'radiation surviving'.

Prochlorococcus, discovered in 1986, is probably the most abundant what on Earth?

This tiny ocean cyanobacterium produces a large share of the world's photosynthetic oxygen; Chisholm won the Crafoord Prize in 2019.

What are the dormant, centuries-surviving structures formed by Bacillus and Clostridium bacteria called?

One report describes viable Bacillus spores in salt crystals about 25 million years old.

Tardigrades, the micro-animals also known as water bears, enter a dried-out survival state called what?

In that state they tolerate near-absolute-zero cold, vacuum, radiation and have survived exposure to outer space.

Baker's and brewer's yeast, which turns sugars into carbon dioxide and alcohol, is which species?

Yeasts are eukaryotic fungi; most reproduce by budding and at least 1,500 species are known.

Mycobacterium tuberculosis resists the Gram stain because of a waxy coat rich in what?

Acid-fast stains such as Ziehl-Neelsen are used instead; the bug divides only every 15 to 20 hours.

Which of these is a sub-discipline of microbiology concerned with fungi?

Microbiology's name comes from the Greek for 'small' and 'life'.

Which ancient Indian religion postulated unseen microscopic life as early as the 6th century BCE?

Jain scriptures describe 'nigodas', sub-microscopic creatures pervading everything; the Roman Varro also warned of unseen creatures in swamp air.

What are the infectious proteins that cause diseases such as BSE called?

Their effects were originally assumed to come from chronic viral infections.

Pasteur's student Adrien Certes is considered the founder of which branch of the science?

Pasteur and Koch's focus on medically relevant microbes long obscured the true diversity of the microbial world.

In which year did Robert Koch win the Nobel Prize in Physiology or Medicine?

The prize cited his tuberculosis work; his attempt to turn tuberculin into a cure is remembered as his greatest failure.

Which river did Koch identify as the source of cholera during his 1883-84 investigation in India?

He had begun in Alexandria, Egypt, and moved to Calcutta as that outbreak faded, autopsying almost 100 bodies.

Which Delft painter's will did Antonie van Leeuwenhoek execute in 1675?

The two were baptised four days apart in a city of about 24,000, and Van Leeuwenhoek may even be the model in The Astronomer and The Geographer.

As of 2025, how many of Van Leeuwenhoek's single-lens microscopes were known to survive?

He built at least 25 of them in silver or copper frames; the survivors magnify up to 275 times.

What was the profession of Robert Koch's father?

Koch, born in Clausthal in 1843, was the third of thirteen children and had taught himself to read before starting school.