CRISPR–Cas-mediated gene editing in lactic acid bacteria

The high efficiency, convenience and diversity of clustered regular interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems are driving a technological revolution in the gene editing of lactic acid bacteria (LAB). Cas-RNA cassettes have been adopted as tools to perform gene deletion, insertion and point mutation in several species of LAB. In this article, we describe the basic mechanisms of the CRISPR–Cas system, and the current gene editing methods available, focusing on the CRISPR–Cas models developed for LAB. We also compare the different types of CRISPR–Cas-based genomic manipulations classified according to the different Cas proteins and the type of recombineering, and discuss the rapidly evolving landscape of CRISPR–Cas application in LAB.