There is this notion that people who study science had a lifelong fascination with it, implying that those who lack this history should pursue another career. Let me tell you: as a kid, I didn’t dream of becoming a scientist. Honestly, I just wanted to be a Jedi, or maybe a ninja (a reasonable fallback plan). Though I soon learned that those dreams wouldn’t work out, for some time I had no idea what I wanted to become. It wasn’t until college that I discovered how remarkable and consequential the microscopic world is. That is to say, it’s never too late to develop a love for microbiology – so let’s explore some reasons why it excites me, and maybe you’ll catch the bug, too!
Horizontal Gene Transfer
Imagine spitting on someone and giving them your eye color, or getting rid of someone’s lactose intolerance with a high five. Many microbes can copy parts of their DNA and pass it to other microbes, a process known as horizontal gene transfer. The recipients then possess the traits encoded on that DNA. This can make distinguishing between different microbial species tricky – how you are you if many of your traits came from your friends?
Microbial populations grow much more quickly than human populations. With enough food, some bacterial species can double their numbers in only 15 minutes! This means they can recover rapidly from damage. For example, antibiotics are designed to wipe out bacteria, but if one cell coincidentally mutates and is able to resist a particular antibiotic, that cell could quickly re-establish a destroyed population, forming one that resists the antibiotic. Random DNA-changing mutations happen all the time, and while this specific change is pretty unlikely in any one cell, odds improve when a population consists of billions. This phenomenon, along with horizontal gene transfer, is not only behind the rise in antibiotic resistance around the world, but it also helps microbes “figure out” how to use nearly anything as a food source – from oil to plastic to pure electricity.
The incredible flexibility of microbial populations has allowed them to colonize some of the most extreme environments on Earth. They have been found a few miles underground, facing pressures greater than 1000 times Earth’s atmosphere. Some species thrive in hydrothermal vents on the seafloor, where temperatures reach well above the boiling point of water. Here, the only thing keeping the water inside the cells from boiling is the immense pressure at this depth. Other organisms can survive in some of the planet’s most acidic waters (pH of 0). These microbes challenge our understanding of life – they humble as much as they fascinate.
As you might guess by its genetic flexibility and massive habitat range, the microbial world is incredibly diverse. It’s hard to fathom the true extent of this diversity, but diagrams of the tree of life, like the one shown below, can help. Look at the green cluster of lineages labelled “Eukaryotes” in the bottom right. This group contains every multicellular organism. Every animal (including humans), plant, and fungus ever discovered falls in that small cluster – everything else is microbial (as is a good chunk of the Eukaryotes). If that wasn’t enough, some estimate that we have yet to discover 99.999% of the planet’s microbial species. The wealth of information among all of this unstudied diversity is perhaps the most tantalizing yet intimidating part of studying microbiology. There is so much to discover; maybe you can help!
Peer edited by Dominika Trzilova .
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