Elena Kurilovich and Konstantin Severinov from Skoltech have co-authored a paper “Bacteriostatic antibiotics promote CRISPR-Cas adaptive immunity by enabling increased spacer acquisition” that has been recently published in Cell Host & Microbe journal. Using bacterium Pseudomonas aeruginosa and its phage DMS3vir as a model, the researchers demonstrate that conditions that reduce bacterial growth rates, such as exposure to bacteriostatic antibiotics that inhibit cell growth without killing, promote the evolution of CRISPR immunity. Furthermore, other environmental factors slowing down cell growth also promote CRISPR-Cas immunity. The authors of the article demonstrate that this is due to slower phage development under these conditions, which provides more time for cells to acquire phage-derived sequences and mount an immune response. They revealed that the speed of phage development is a key determinant of the evolution of CRISPR immunity. Thus, one may suggest that use of bacteriostatic antibiotics can trigger elevated levels of CRISPR immunity in human-associated and natural environments. Full text of the paper is available here.