Removing a Molecular Brake to Enhance Antimicrobial Activity
New CRISPR/Cas9 approach enhances natural antimicrobial activity in Lactiplantibacillus plantarum
Lactic acid bacteria naturally produce a range of compounds that can inhibit other microorganisms. Researchers at DWI have now shown how targeted genome editing can strengthen this antimicrobial activity in L. plantarum, while at the same time establishing a CRISPR/Cas9 workflow for a bacterial strain that has previously been difficult to genetically modify.
In a new study published in the Journal of Biological Engineering, Rajat Anand and colleagues at DWI adapted and optimized an optimized an established CRISPR/Cas9-based genome-editing approach for L. plantarum 8P-A3. The bacterium naturally produces antimicrobial peptides called plantaricins, whose production is controlled by a network of signaling and regulatory genes.
Removing a molecular brake
The researchers set their sights on plnD, a regulatory gene involved in the bacterium’s quorum-sensing system. In simple terms, this system enables bacteria to coordinate their gene activity in response to chemical signals. In this case, plnD acts as a negative regulator of plantaricin production.
By specifically disrupting this gene, the researchers were able to remove this molecular “brake”. The challenge, however, was getting CRISPR/Cas9 – often described as “molecular scissors” – to function efficiently in L. plantarum 8P-A3 – a strain that has proven difficult to genetically modify because of its thick peptidoglycan cell wall, low transformation efficiency and other strain-specific barriers.
Through systematic optimization of the genome-editing conditions, Rajat Anand successfully generated a stable modified strain. Compared with the unmodified bacterium, it showed substantially increased expression of the plantaricin-associated genes several genes plnA, plnE and plnF.
More than a genetic change
The genetic modification also translated into a measurable functional effect. Compared with the unmodified strain, the engineered bacteria displayed increased antimicrobial activity in laboratory assays against a sensitive L. plantarum indicator strain.
The results demonstrate that a bacterial signaling network can be rationally reconfigured to increase the expression of plantaricin-associated genes and thus enhance antimicrobial activity. At the same time, the optimized CRISPR/Cas9 workflow provides a practical platform for further genetic engineering of L. plantarum 8P-A3 and potentially related lactic acid bacteria.
A step towards engineered living antimicrobials
The study opens up new possibilities for tailoring lactic acid bacteria with enhanced antimicrobial properties for food, biotechnological, and therapeutic applications. Such engineered microorganisms could contribute to new approaches in areas where conventional antibiotics face increasing challenges, including the development of next-generation antimicrobial strategies.
For now, further research will be needed to explore investigate the stability, safety, and functional efficacy of these engineered bacteria in more complex biological environments and to determine whether their enhanced antimicrobial activity also extends to clinically or industrially relevant microorganisms.
Publication details:
Rajat Anand, Rudolf Lütticken, Laura De Laporte, Andreas Herrmann & Elisabeth Heine, “An optimized CRISPR/Cas9-based genome editing platform enhances bacteriocin production in Lactiplantibacillus plantarum.” Journal of Biological Engineering vol. 20,1 121. 29 Jul. 2026, doi:10.1186/s13036-026-00739-5. PMID: 42527938; PMCID: PMC13420864.