Micro Tale: Secrets of a Superpower
Our story as a species spans hundreds of thousands of years. And the history of bacteria spans billions of years. In that time, microbes have seen it all — the wide range of temperatures and pressures, all sorts of concentrations of countless chemical substances, the emergence of life on land, the formation of continents, dinosaurs, pterodactyls, giant ferns, and our ancestors hunting mammoths. So, honestly, penicillin or even synthetic antibiotics are unlikely to surprise them much.
Besides the fact that we and bacteria have different histories in terms of duration, we also move along at different speeds in terms of evolution. What does that mean? The time between our generations is measured in decades, while for bacteria it is tens of minutes. Condensed, while our children are just starting school, hundreds of thousands of generations of bacteria may have passed! Our species doesn’t even exist for that long. Therefore, bacterial evolution moves at a pace that is simply incredibly fast, difficult for us to imagine!
The cells of bacteria and archaea (the difference between them is noted here here), in comparison with the cells of our bodies, have a very simple structure. On the one hand, not so simple that we can confidently claim we know everything about them, and on the other — this is precisely the case where simplicity is a hallmark of genius, because it allows for such wild feats that would be impossible in more complex constructions.
For example, bacteria are characterized by horizontal gene transfer. We and other living organisms pass on our genes vertically, i.e., from generation to generation, while bacteria can simply pick up someone’s DNA from the environment, which, for instance, codes for antibiotic resistance, and use it to their advantage, while we do not. And it doesn’t even require that the bacteria be of the same species! It would be like us being able to jump like a kangaroo just by eating its fur! Magic, right?
And microbes also have a devil-may-care appetite and diverse tastes — they gladly consume carbon dioxide, hydrogen sulfide, ammonium sulfates, nitrates, iron, phenols, and even some antibiotics that, it would seem, should kill them! This is because they have a wide diversity of metabolic types, about which we can hardly even imagine. We’ll try to explain this briefly and in the simplest terms:
For all living organisms to exist, they must obtain energy, carbon, and electrons. We obtain all of this from ready-made organic substances — buckwheat porridge, a steak, or a salad made from sprouted grains. Therefore, we are chemoorganoheterotrophs. Let’s break down: the first part of the word "chemo-" means energy source, so all those who are not capable of photosynthesis obtain energy from ready organic matter, so they are chemotrophs; plants, for example, which are enough just to have the sun shine — are phototrophs; the second part of this scary word means the source of electrons and can be "organo-" — when the source of electrons is organic substances, as in us, or "lito-" — inorganic substances. The third part of the construction — "auto-" or "hetero-" — tells about the source of carbon — organic or inorganic substances.
For example, your cactus, as a representative of the plant world, is a photolithoautotroph, because it obtains energy from sunlight, electrons from water, and carbon from carbon dioxide.
And only among bacteria, besides the two previously mentioned types of metabolism, there exists a wide variety of chemolithoautotrophs, chemolithotrophs, photoorganoheterotrophs, photoorganoautotrophs, and photolithoheterotrophs. It is precisely because of such broad possibilities that bacteria occupy this key unique role in the geochemical transformations on our planet.
Moreover, some microbes can change their metabolism type depending on environmental conditions: if there is light — we photosynthesize, if there is organic matter — we eat organic matter. And you? ;)
