Electronic “programming” of cell populations

Diagram for programming electrogenetic lysis into bacterial cells. (Download Image)

Programming electrogenetic lysis into bacterial cells. Cells are genetically engineered to respond to hydrogen peroxide (H2O2) produced by a gold electrode and self-lyse (breakdown) as a response. Different synthetic biology communication schemes were tested to assess signal response and design space.

Cell death and lysis (breakdown of a cell) play an important role in a wide array of biological processes. Scientists propose that the genetic “programming” of microbial cell lysis could provide new methodologies for biomanufacturing and biocontainment. To this end, LLNL and collaborators at the University of Maryland are focused on developing robust and generalizable cellular and population level containment mechanisms for improving the use of plant benefiting microbes in the rhizosphere—a soil layer that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome.

In a recent experimental study, researchers set out to mimic the behavior of the rhizosphere, where plant-derived hydrogen peroxide (H2O2) initiates a complex communication network, signaling various microbial functions and microbiome interactions. To do this, they used a gold electrode to externally apply electronic signals capable of locally producing H2O2, therefore initiating genetic circuits that biologically mediate cell lysis. This is known as electrogenetic signaling, i.e., the combination of electronics and genetics.

Two methods were tested. The first explored the direct electronic activation of cell lysis within a clonal population of cells. This required microbial cells to be in close proximity to the H2O2 producing electrode and long signal-durations to effectively activate the lysis switch within the majority of the population. In comparison, the second method transformed the electrogentic signal to a quorum sensing signal—a communication mechanism between bacteria that relies on a bacterially produced small (quorum) molecule to control specific cell processes—which transmitted the lytic signals to neighboring bacteria. This dramatically reduced both the time and input energy requirements needed to activate lysis in a majority of the population.

Overall, the transformation of electronically produced H2O2 into native biological signals that induce quorum sensing dramatically enhanced cell lysis. Future applications of electrogenetic lysis systems will be useful for illuminating the physiology of microbial consortia, as well as potentially controlling synthetic microbial consortia for biomanufacturing and biocontainment applications.

[E. VanArsdale, A. Navid, M. J. Chu, T. M. Halvorsen, G. F. Payne, Y. Jiao, W. E. Bentley, and M. C. Yung, Electrogenetic signaling and information propagation for controlling microbial consortia via programmed lysisBiotechnology and Bioengineering (2023), doi: 10.1002/bit.28337.]