Developing Cyanobacterial Quorum Sensing Toolkits: Toward Interspecies Coordination in Mixed Autotroph/Heterotroph Communities

Abstract

There has been substantial recent interest in the promise of sustainable, light-driven bioproduction using cyanobacteria, including developing efforts for microbial bioproduction using mixed autotroph/heterotroph communities, which could provide useful properties, such as division of metabolic labor. However, building stable mixed-species communities of sufficient productivity remains a challenge, partly due to the lack of strategies for synchronizing and coordinating biological activities across different species. To address this obstacle, we developed an inter-species communication system using quorum sensing (QS) modules derived from well-studied pathways in heterotrophic microbes. In the model cyanobacterium, Synechococcus elongatus PCC 7942 (S. elongatus), we designed, integrated, and characterized genetic circuits that detect acyl-homoserine lactones (AHLs), diffusible signals utilized in many QS pathways. We showed that these receiver modules sense exogenously supplied AHL molecules and activate gene expression in a dose-dependent manner. We characterized these AHL receiver circuits in parallel with Escherichia coli W (E. coli W) to dissect species-specific properties, finding broad agreement, albeit with increased basal expression in S. elongatus. Our engineered “sender” E. coli strains accumulated biologically synthesized AHLs within the supernatant and activated receiver strains similarly to exogenous AHL activation. Our results will bolster the design of sophisticated genetic circuits in cyanobacterial/heterotroph consortia and the engineering of QS-like behaviors across cyanobacterial populations.

Cyanobacteria as cell factories for the photosynthetic production of sucrose

“…Adaptative laboratory evolution could be a useful strategy to domesticate increasingly stable co-cultures by better integrating and adapting the partners to one another ( Konstantinidis et al, 2021 ). Rational engineering strategies to generate more intricate coordination of activities between species and at the population level might also contribute to this goal ( Kokarakis et al, 2022 ). Cyanobacterial and heterotrophic partner species that have been more extensively designed to cooperate and coordinate would also be likely to exhibit higher end-product titers relative to the current productivities achievable from co-culture.…”

Synthetic Light‐Driven Consortia for Carbon‐Negative Biosynthesis

“…AHL synthases were expressed in sucrose‐utilizing E. coli W. The cscB and sucrose phosphate synthase coding gene sps were expressed under S. elongatus AHL promoters for regulating the sucrose yield in the medium by linking sucrose export with E. coli cell numbers. This study could bolster the toolkits of quorum sensing in phototroph‐heterotroph co‐culture systems and the engineering of QS‐like behaviors in synthetic light‐driven consortia [23] . Thus, QS‐based cell‐cell communication systems offer great opportunities for multiple control of artificial microbial consortia.…”

“…This study could bolster the toolkits of quorum sensing in phototroph-heterotroph co-culture systems and the engineering of QS-like behaviors in synthetic lightdriven consortia. [23] Thus, QS-based cell-cell communication systems offer great opportunities for multiple control of artificial microbial consortia.…”