Intra and interspecies control of bacterial growth through extracellular extracts

A variety of bacterial species colonize the human body, many of which reside in the gut microbiome. The disruption of the gut microbiome is linked to several digestive issues and chronic health conditions, such as obesity, Clostridium difficile (C. difficile) infections and colorectal cancer. Bacteria utilize extracellular quorum sensing molecules to communicate, which impacts bacterial growth, resistance to antibiotics, and differential expression of genes. Influence and control over these systems is of clinical importance in treating bacterial infections, such as by modifying a patient’s gut microbiome. This study measured the impact of bacteria-free supernatants collected from Escherichia coli (E. coli), samples from the bacterial environments likely containing quorum sensors, in the death and log phases on the growth of new cultures of E. coli and Enterobacter aerogenes (E. aerogenes). Exposure to E. coli death phase clarified supernatant inhibited E. coli growth by 21.41% - 81.24% and E. aerogenes growth by 19.43% - 58.62%. While E. coli log phase clarified supernatant induced E. coli growth by 15.08% - 52.61% and E. aerogenes growth by 29.93% - 107.52%. A combination of these supernatants could potentially be used to fine-tune population sizes of bacteria in the gut microbiome, rebalancing an altered gut microbiome. Future experiments could characterize the macromolecules within the clarified supernatants, explore their degradation pathways, and how they interact with each other.