Encapsulation-enhanced genetic switches in lactobacilli

Lactiplantibacillus plantarum , a versatile member of the lactobacillus family, is widely recognized for its potential in healthcare, food production, and environmental biotechnology. Despite its inherent advantages and demonstrated potential as microbial chassis for biotechnological applications, its broader utility is constrained by a limited genetic toolbox, particularly the lack of robust genetic switches for inducible gene expression. Addressing this gap, we report the development of a novel genetic switch for L. plantarum based on a strong bacteriophage-derived promoter and the food-grade inducer, cumate. The dynamic range and temporal profile of this switch exhibits interesting temperature and growth phase dependence that influence its leakiness and induced protein production levels. In the process of identifying ways to overcome both dependencies, we discovered that encapsulation of L. plantarum in alginate seemingly traps them in a growth-phase that maximizes the performance of the switch. For the first time, we show how a material-oriented strategy can be leveraged to improve an engineered gene regulation function in bacteria. Furthermore, this engineered living material approach is promising for developing L. plantarum towards advanced applications in biotechnology, pharmaceutics, and living therapeutics.