Microbes 101: What is Horizontal Gene Transfer?
We humans get our genome from our biological parents, roughly half from our mother and half from our father. This genetic legacy connects us through the generations to our ancestors.
But what if you could directly swap and trade DNA at will with any other human? It might work something like this: say your best friend comes over for a visit, and when she arrives, you hug her, and during that hug, you trade some genes. You are both now different genetically than you were before the hug.
You each still have your “vertical” genetic inheritance from your parents, but a “horizontal,” peer-to-peer inheritance has been added.
This scenario is pure science fiction, but in the microbial community, bacteria extensively practice what’s known as horizontal gene transfer, swapping packets of genetic information that can give them new capabilities. Such new capabilities include the ability to thwart antibiotics, and horizontal gene transfer is one of the ways antibiotic resistance can sweep through a microbial population. So while we use organizational schemes like the Tree of Life to depict all known lifeforms and show ancestral origins and evolutionary paths, microbes show us that evolution is not always a tree branching upward; sometimes it jumps from branch to branch, sideways. This has huge implications: for instance, have microbes exchanged their genes with other kinds of organisms? With humans? Are we … part microbe?! (Spoiler: the answer is yes).
I Contain Multitudes is a multi-part video series dedicated to exploring the wonderful, hidden world of the microbiome.
