Microbiology should be part of everyone’s educational experience. European students deserve to know something about the influence of microscopic forms of life on their existence, as it is at least as important as the study of the Roman Empire or the Second World War. Knowledge of viruses should be as prominent in American high school curricula as the origin of the Declaration of Independence. This limited geographic compass reflects the fact that the science of microbiology is a triumph of Western civilization, but the educational significance of the field is a global concern. We cannot understand life without an elementary comprehension of microorganisms.
Appreciation of the microbial world might begin by looking at pond water and pinches of wet soil with a microscope. Precocious children could be encouraged in this fashion at a very early age. Deeper inquiry with science teachers would build a foundation of knowledge for teenagers, before the end of their formal education or the pursuit of a university degree in the humanities.
Earth has always been dominated by microorganisms. Most genetic diversity exists in the form of microbes and if animals and plants were extinguished by cosmic bombardment, biology would reboot from reservoirs of this bounty. The numbers of microbes are staggering. Tens of millions of bacteria live in a crumb of soil. A drop of seawater contains 500,000 bacteria and tens of millions of viruses. The air is filled with microscopic fungal spores, and a hundred trillion bacteria swarm inside the human gut. Every macroscopic organism and every inanimate surface is coated with microbes. They grow around volcanoes and hydrothermal vents. They live in blocks of sea ice, in the deepest oceans, and thrive in ancient sediment on the seafloor. Microbes act as decomposers, recycling the substance of dead organisms. Others are primary producers, turning carbon dioxide into sugars using sunlight or by tapping chemical energy from hydrogen sulfide, ferrous iron, ammonia, and methane.
Bacterial infections are caused by decomposers that survive in living tissues. Airborne bacteria cause diphtheria, pertussis, tuberculosis, and meningitis. Airborne viruses cause influenza, measles, mumps, rubella, chickenpox, and the common cold. Hemorrhagic fevers caused by Ebola viruses are spread by direct contact with infected patients. Diseases transmitted by animal bites include bacterial plague, as the presumed cause of the Black Death, which killed 200 million people in the 14th century. Typhus spread by lice decimated populations of prisoners in concentration camps and refugees during the Second World War. Malaria, carried by mosquitos, massacres half a million people every year.
Contrary to the impression left by this list of infections, relatively few microbes are harmful and we depend on a lifelong cargo of single-celled organisms and viruses. The bacteria in our guts are essential for digesting the plant part of our diet and other bacteria and yeasts are normal occupants of healthy skin. The tightness of our relationship with microbes is illustrated by the finding that human DNA contains 100,000 fragments of genes that came from viruses. We are surprisingly microbial.
Missing the opportunity to learn something about microbiology is a mistake. The uninformed are likely to be left with a distorted view of biology in which they miscast themselves as the most important organisms. For example, “Sarah” is a significant manifestation of life from Sarah’s perspective, but her body is not the individual organism that she imagines, and nor, despite her talents, is she a major player in the ecology of the planet. Her interactions with microbes will include a healthy relationship with bacteria in her gut, bouts of influenza and other viral illnesses, and death in old age from an antibiotic-resistant infection. Sarah’s microbiology will continue after death with her decomposition by fungi. In happier times she will become an expert on Milton’s poetry, and delight students by reciting Lycidas through her tears, but she will never know a thing about microbiology. This is a pity. Learning about viruses that bloom in seawater and fungi that sustain rainforests would not have stopped her from falling in love with Milton.
Even brief consideration of microorganisms can be inspiring. A simple magnifying lens transforms the surface of rotting fruit into a hedgerow of glittering stalks topped with jet-black fungal spores. Microscopes take us deeper, to the slow revolution of the bright green globe of the alga Volvox as its beats its way through a drop of pond water. A greater number of microbes are quite dull things to look at and their appreciation requires greater imagination. Considering that our bodies are huge ecosystems supported by trillions of bacteria is a good place to start, and then we might realize that we fade from view against the grander galaxy of life on Earth. The science of microbiology is a marvel for our time.
Featured image credit: BglII-DNA complex By Gwilliams10. Public domain via Wikimedia Commons
The post Discovering microbiology appeared first on OUPblog.
By Nicholas P. Money
The small picture is the big picture and biologists keep missing it. The diversity and functioning of animals and plants has been the meat and potatoes of most natural historians since Aristotle, and we continue to neglect the vast microbial majority. Before the invention of the microscope in the seventeenth century we had no idea that life existed in any form but the immediately observable. This delusion was swept away by Robert Hooke, Anton van Leeuwenhoek, and other pioneers of optics who found that tiny forms of life looked a lot like the cells that comprise our own tissues. We were, they showed, constructed from the same essence as the writhing animalcules of ponds and spoiled food. And yet this revelation was somehow folded into the continuing obsession with human specialness, allowing Carolus Linnaeus to catalogue plants and big animals and ignore the lilliputian majority. When microbiological inquiry was restimulated by Louis Pasteur in the nineteenth century, it became the science of germs and infectious disease. The point was not to glory in the diversity of microorganisms but exterminate them. In any case, as before, most of life was disregarded.
Things are changing very swiftly now. Molecular fishing expeditions in which raw biological information is examined using metagenomic methods have discovered an abundance of cryptic life forms. This research has made it clear that we are a very long way, centuries perhaps, from comprehending biodiversity properly.
Revelation of the human microbiome, the teeming trillions of bacteria and archaea in our guts that affect every aspect of our wellbeing, is the best publicized part of the inquiry. We are walking ecosystems, farmed by our microbes and dependent upon their metabolic virtuosity. There is much more besides, including the fact that a single cup of seawater contains 100 million cells, which are in turn preyed upon by billions of viruses; that a pinch of soil teems with incomprehensibly rich populations of cells; and that 50 megatons of fungal spores are released into our air supply every year. Even the pond in my Ohio garden is filled with unknowable riches: the most powerful techniques illuminate the genetic identity of only one in one billion of the cells in its shallow water.
Most biologists continue to be concerned with animals and plants, the thinnest slivers of biological splendor, and students are taught this macrobiology—with the occasional nod toward the other things that constitute almost all of life. Practical problems abound from this nepotism. Ecologists study things muscled and things leafed and conservationists worry most about animals, arguing for expensive stamp-collecting exercises to register the big bits of creation before they go extinct. This is a predicament of considerable importance to humanity. Consider: A single kind of photosynthetic bacterium absorbs 20 billion tons of carbon per year, making this minuscule cell a stronger refrigerant than all of the tropical rainforests.
Surveying our planet for its evolutionary resources, the perceptive extraterrestrial would report that Earth is swarming with viral and bacterial genes. The visitor might comment, in passing, that a few of these genes have been strung together into large assemblies capable of running around or branching toward the sunlight. It is time for us to embrace this kind of objectivity and recognize that the macrobiological bias that drives our exploration and teaching of biology is no more sensible than attempting to evaluate all of English Literature by reading nothing but a Harry Potter book. The science of biology would benefit from a philosophical reboot.
Nicholas P. Money is Professor of Botany and Western Program Director at Miami University in Oxford, Ohio. He is the author of more than 70 peer-reviewed papers on fungal biology and has authored several books. His new book is The Amoeba in the Room: Lives of the Microbes.
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Image Credit: Scanning electron micrograph of amoeba, computer-coloured mauve. By David Gregory & Debbie Marshall, CC-BY-NC-ND 4.0, via Wellcome Images.
The post The amoeba in the room appeared first on OUPblog.
By Nicholas P. Money
A grown-up neighbor in the English village of my childhood told stories about angels that sat upon our shoulders and fairies that lived in her snapdragons. Like the other kids, I searched her flowers for a glimpse of the sprites, but agnosticism imbibed from my parents quickly overruled this innocent play. Yet there was magic in my neighbor’s garden and I had seen real angels on her lawn: little stalked bells that poked from the dew-drenched grass on autumn mornings; evanescent beauties whose delicately balanced caps quivered to the touch. By afternoon they were gone, shriveled into the greenery. Does any living thing seem more supernatural to a child than a mushroom? Their prevalence in fairy tale illustrations and fantasy movies suggests not. Like no other species, the strangeness of fungi survives the loss of innocence about the limits of nature. They trump the supernatural, their magic intensifying as we learn more about them.
Once upon a time, I spent 30 years studying mushrooms and other fungi. Now, as my scientific interests broaden with my waistline, I would like to share three things that I have learned about the meaning of life from thinking about these extraordinary sex organs and the microbes that produce them. This mycological inquiry has revealed the following: (i) life on land would collapse without the activities of mushrooms; (ii) we owe our existence to mushrooms; and (iii) there is (probably) no God. The logic is spotless.
Mushrooms are masterpieces of natural engineering. The overnight appearance of the fruit body is a pneumatic process, with the inflation of millions of preformed cells extending the stem, pushing earth aside, and unfolding the cap. Once exposed, the gills of a meadow mushroom shed an astonishing 30,000 spores per second, delivering billions of allergenic particles into the air every day. A minority of spores alights and germinates on fertile ground and some species are capable of spawning the largest and longest-lived organisms on the planet. Mushroom colonies burrow through soil and rotting wood. Some hook into the roots of forest trees and engage in mutually supportive symbioses; others are pathogens that decorate their food sources with hardened hooves and fleshy shelves. Mushrooms work with insects too, fed by and feeding leaf-cutter ants in the New World and termites in the Old World. Among the staggering diversity of mushroom-forming fungi we also find strange apparitions including gigantic puffballs, phallic eruptions with revolting aromas, and tiny “bird’s nests” whose spore-filled eggs are splashed out by raindrops.
Mushrooms have been around for tens of millions of years and their activities are indispensable for the operation of the biosphere. Through their relationships with plants and animals, mushrooms are essential for forest and grassland ecology, climate control and atmospheric chemistry, water purification, and the maintenance of biodiversity. This first point, about the ecological significance of mushrooms, is obvious, yet the 16,000 described species of mushroom-forming fungi are members of the most poorly understood kingdom of life. The second point requires a dash of lateral thinking. Because humans evolved in ecosystems dependent upon mushrooms there would be no us without mushrooms. And no matter how superior we feel, humans remain dependent upon the continual activity of these fungi. The relationship isn’t reciprocal: without us there would definitely be mushrooms. Judged against the rest of life (and, so often, we do place ourselves against the rest of nature) humans can be considered as a recent and damag
