In 1702 Leeuwenhoek watched dried-out animalcules come back to life
Antonie van Leeuwenhoek let the water around tiny rotifers evaporate, expecting them to burst. Instead they curled into ovals and waited; add water, and they swam again. He had glimpsed a survival trick many microbes use, a cyst stage of suspended animation, though nobody gave it a name for well over a century.
A microbial cyst is a dormant form in which a single-celled organism slows its metabolism almost to a standstill and stops feeding and moving. Many groups of microbes can enter it. Triggers include shortages of food or oxygen, extreme heat or cold, drying out, the wrong acidity and toxic chemicals. When conditions improve, the cyst wall breaks down in a process called excystation and normal life resumes.
Encystment does more than wait out bad times. It lets organisms travel between habitable places, surviving the hostile gap in between, and cysts can also be where nuclei reorganise and cells divide. In parasitic species the cyst is often the infectious stage that passes from one host to the next.
The history is tangled. Leeuwenhoek's 1702 observations on what we now call rotifers drew little attention in his day. In 1743 John Turberville Needham revived the encysted larvae of a wheat parasite and published the results in 1745, and others followed with studies of what they called reviviscence. In the late 1850s the question collided with the debate over spontaneous generation. Doyère, who believed dried rotifers could revive, and Pouchet, who thought not, asked the Biological Society of France for an independent review. Its report leaned toward Pouchet, though its main author later said fear of religious backlash had shaped how he framed the matter.
Terminology stayed muddled. Wilhelm Preyer coined anabiosis, return to life, in 1872 for bringing apparently lifeless but viable organisms back to activity. Schmidt proposed abiosis in 1948, adding confusion between words for life arising from non-living matter, suspended life, and the non-living ingredients life requires.
Source: Microbial cyst
