In a groundbreaking study from the Scojen Institute for Synthetic Biology at Reichman University, researchers have discovered that beneficial bacteria like Bacillus subtilis can pass on stress resistance and colonization skills across generations, paving the way for advancements in agricultural and probiotic applications. This memory enables them to express genes associated with colonization and symbiosis with their host for generations, even after being separated from the host.

The ability to transfer information across generations allows these bacteria to recolonize new hosts efficiently, giving them a competitive edge over naïve bacteria that have never formed stable interactions with plants. The genes with multigenerational inheritance patterns are linked to stress resistance, underscoring the significance of the defenses developed during plant colonization. This multigenerational inheritance stabilizes the beneficial bacteria's interactions with their hosts. Researchers believe that similar mechanisms facilitate long-term interactions of beneficial probiotic bacteria in the human gut, offering prolonged protection against disease.

Dr. Ilana Kolodkin-Gal of the Scojen Institute remarked, “Our research findings make it possible to manipulate the identified genes to create synthetic circuits with memory for agricultural and industrial applications and to improve the engineering of probiotic bacteria, whose average lifespan is about 30 minutes. We aim for them to act in accordance with the signal they receive for hours or even days.”

Published recently in Microbiological Research, the study was a collaborative effort with Jonathan Friedman’s group from the Hebrew University of Jerusalem and Asaph Aharoni’s group from the Weizmann Institute of Science. Dr. Omri Gilhar from the Weizmann Institute of Science and Dr. Liat Rahamim-Ben Navi from the Scojen Institute  were among the contributing researchers.

The authors listed the following as some key highlights from their findings:

• B. subtilis is a beneficial bacterium that promotes plant growth and defends plants against pathogens.
• Cells of B. subtilis that have contacted the plant's root or its secretions show better stress tolerance and are more effective at colonizing roots than those not exposed to the root.
• Plant exudations, rather than simple carbons or nitrogen, fundamentally alter the bacteria's transcriptome and intracellular signaling, a signature maintained by their descendants.
• Bacteria develop a "memory" that allows them to adapt to plant hosts over multiple generations by activating the stress response system, providing a competitive advantage.

"We found that bacteria previously associated with the root or exposed to its secretions had greater stress tolerance and were more competitive in root colonization than bacteria not previously exposed to the root," the authors stated. "Furthermore, our transcriptome results provide evidence that plant secretions induce a microbial stress response and fundamentally alter signaling by the cyclic nucleotide c-di-AMP, a signature maintained by their descendants."

The authors concluded, "Our work demonstrates a bacterial memory manifested by multigenerational reversible adaptation to plant hosts in the form of activation of the stressosome, which confers an advantage to symbiotic bacteria during competition."