CRISPR-Cas has become famous as a versatile and effective genome editing technology, but its original function as an adaptive immune system in bacteria is equally amazing. Bacteria are found in almost every environment on Earth, including the human body, and where there are bacteria there are also viruses that infect bacteria. The CRISPR-Cas immune system is one defense mechanism bacteria have in their toolkit – bacteria can store pieces of virus DNA and “remember” past virus attackers.

We will take a tour through the world of microbial ecology. I will talk about the intricate dance between bacteria and viruses, where CRISPR-Cas enters the story as both an immune system and a powerful genome editing tool, and how physics can help us understand the invisible life teeming all around us.