An engineered live biotherapeutic for the prevention of antibiotic-induced dysbiosis

A strain of Lactococcus lactis engineered to altruistically degrade beta-lactam antibiotics through the secretion and extracellular assembly of a heterodimeric beta-lactamase prevented dysbiosis in the gut of mice treated with ampicillin. Antibiotic-induced alterations in the gut microbiota are implicated in many metabolic and inflammatory diseases, increase the risk of secondary infections and contribute to the emergence of antimicrobial resistance. Here we report the design and in vivo performance of an engineered strain of Lactococcus lactis that altruistically degrades the widely used broad-spectrum antibiotics beta-lactams (which disrupt commensal bacteria in the gut) through the secretion and extracellular assembly of a heterodimeric beta-lactamase. The engineered beta-lactamase-expression system does not confer beta-lactam resistance to the producer cell, and is encoded via a genetically unlinked two-gene biosynthesis strategy that is not susceptible to dissemination by horizontal gene transfer. In a mouse model of parenteral ampicillin treatment, oral supplementation with the engineered live biotherapeutic minimized gut dysbiosis without affecting the ampicillin concentration in serum, precluded the enrichment of antimicrobial resistance genes in the gut microbiome and prevented the loss of colonization resistance against Clostridioides difficile. Engineered live biotherapeutics that safely degrade antibiotics in the gut may represent a suitable strategy for the prevention of dysbiosis and its associated pathologies.