Current application and future prospects of CRISPR-Cas in lactic acid Bacteria: A review

Lactic acid bacteria (LABs) have a long history of use in food and beverages fermentation. Recently, several LABs have gained attention as starter or non-starter cultures and probiotics for making functional fermented foods, which have the potential to enhance human health. In addition, certain LABs show great potential as microbial cell factories for producing food-related chemicals. However, enhancing the outcomes of starter and non-starter cultures, exploring the complicated probiotic mechanism of LABs, and engineering strains to enhance the yields of high-value compounds for precision fermentation remains challenging due to the time-consuming and labor-intensive current genome editing tools. The clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR associated proteins (Cas) system, originally an adaptive immune system in bacteria, has revolutionized genome editing, metabolic engineering and synthetic biology. Its versatility has resulted in extensive applications across diverse organisms. The widespread distribution of CRISPR-Cas systems and the diversity of CRISPR arrays in LAB genomes highlight their potential for studying the evolution of LABs. This review discusses the current advancement of CRISPR-Cas systems in engineering LABs for food application. Moreover, it outlines future research directions aimed at harnessing CRISPR-Cas systems to advance lactic acid bacterial research and drive innovation in food science.