A Probiotic Organism’s Delivery of CRISPR Expression Vectors Engineered with a Low-Magnesium-Induced Biosensor for the CRISPR-Cas13b Knockdown of ACC in EHEC Intestinal Pathogens

Objective: The overuse of antibiotics has led to the worldwide proliferation of antibiotic resistant and pathogenic bacteria, in which antibiotic resistant pathogens have become increasingly problematic for the medical community. Pathogenic bacteria such as enterohemorrhagic Escherichia coli and enteropathogenic E. coli cause bloody diarrhoea and are a byproduct of many gastrointestinal disorders. Overuse of antibiotics has increased the proliferation of antibiotic resistant and pathogenic bacteria. Probiotics have been used to treat and prevent pathogenic E. coli infections; however, the probiotics currently used are limited in the ability to specifically target and treat colonic diseases due to a lack of understanding of probiotic mechanisms of action during their production. As a consequence, using synthetic biological methods to engineer probiotics may allow a more precise targeting and treatment of many colonic diseases. One such synthetic biological tool includes modifying probiotic organisms with recombinant plasmids to more accurately prevent and treat intestinal infections. Probiotic bacterial strains could be engineered with a Clustered Regularly Interspaced Short Palindromic Repeat expression plasmid to help reduce bacterial pathogens in the colon. The CRISPR expression plasmid could be designed to inhibit essential enzymes required for the function of many biological processes in pathogenic bacteria, such as the acetyl-CoA carboxylase enzyme needed for fatty acid synthesis. However, more research is required for discovering new strategies that can more effectively deliver CRISPR-based antibacterials to reduce the pathogenic bacteria present in the colon. Results: Conclusion: Therefore, this review will discuss the immense potential and the limitations of utilising engineered probiotic organisms to deliver CRISPR-based gene therapies into the gastrointestinal tract. The review will specifically explore a novel gene therapy, of which probiotic organisms deliver recombinant plasmids engineered with synthetic gene circuits that can sense low intestinal magnesium levels and induce the release of CRISPR/Cas13b effectors to inhibit ACC in target EHEC bacterial cells to potentially clear EHEC pathogens from the colon.