Masters of the Extreme

So much for microscopic Not all microorganisms are invisible to the naked eye. The largest species of bacteria discovered to date, Thiomargarita magnifica, certainly lives up to its name: while average bacteria measure roughly one micrometre (one thousandth of a millimetre), this thread-like single-cell organism found in the waters of Caribbean mangrove forests can grow to an impressive two centimetres in length. [1]

State microbes In 2019, Streptomyces griseus was declared the official »state microbe« of New Jersey. The US state took this action to recognize the contribution made by the bacterium, which was discovered in New Jersey in the 1940s, to the production of streptomycin—a powerful antibiotic used to treat tuberculosis. The microbiologist Selman Waksman received the Nobel Prize in Medicine for his research into the microbe and streptomycin. [2]

Microorganisms are mass manufacturers Microalgae and cyanobacteria in the oceans account for a substantial proportion of all global CO2 fixation. Consequently, these microorganisms also account for a considerable amount of all oxygen production. However, it’s not only the Earth’s atmosphere that is shaped by microbial processes: the microalgae Gephyrocapsa huxleyi produces large quantities of calcium carbonate. The result is chalk cliffs, giving
entire stretches of coastline—including in southern England, Denmark and Rügen—their unmistakeable character and inspiring artists such as Caspar David Friedrich. [3, 4]

Eight per cent of the human genome originates from viruses Humans, like most other mammals, owe our ability to carry our children in the womb to viruses. A human embryo’s ability to attach itself to the mucosal membrane in the uterus, suppressing the mother’s immune system to prevent rejection of the »intruder«, is a characteristic that originated in viral DNA. [5, 6]

Witnesses to the age of dinosaurs Several years ago, researchers woke microorganisms from a particularly deep slumber, having survived 100 million years without light or nutrients, subject to extreme pressures several kilometres underground. However, these aren’t the oldest on record. Instead, the oldest microbes discovered to date were found in a
sort of stand-by mode in deep layers of rock, having reached an age of at least two billion years. [7, 8]

Life in inhospitable locations Microorganisms are true survivalists. Some have settled in locations where life would appear impossible—including the Atacama Desert in Chile, the driest region anywhere on Earth. In this practically water-free environment, archaea such as Halococcus salifodine survive inside rocks and salt crystals. Other microbes thrive in extreme heat: Pyrococcus furiosus, for instance, proliferates in temperatures around 100°C. These archaea, which occur in sediments in the vicinity of active volcanoes, also provide scientists with a thermostable enzyme used in polymerase chain reaction (PCR), a widespread DNA amplification method. [9, 10, 11]

Microorganisms are feasting on the Titanic For almost 113 years, the Titanic has been lying on the floor of the North Atlantic, close to 4,000 metres below the surface. The luxury steamer sank in April 1912. Now, however, its days are numbered, as a species of bacteria called Halomonas titanicae is feeding on the iron in the ship. Rough estimates suggest that the almost 54,000 tonne wreck could be fully devoured by 2030. [12]

Fungus draws on radiation as an energy source Rather than relying on sunlight, fungi such as Cladosporium sphaerospermum draw on radiation as a source of energy. This mould fungus is capable of absorbing radiation with the help of melanin, a dark pigment, before using this radiation for metabolic processes. It has blossomed in locations including the irradiated ruins of Chernobyl nuclear power station. However, exactly how the fungus manages to prevent damage to its genetic material remains unknown. [13, 14]