Role of Carbon Dioxide in the Regulation of Adaptive Proliferation in Bacteria

The adaptive proliferation of bacteria, or cell division in the absence of an exogenous substrate, is controlled by density-dependent mechanisms with the participation of AHL- and AI-2-dependent quorum sensing systems. Along with the signaling molecules of these bacterial communication systems, bacterial metabolites that are permanently released during microbial metabolism, for example, CO₂, can also participate in the regulation and can serve as biomarkers of cell density. It has been found that carbon dioxide is necessary to the adaptive proliferation initiation, and the elevated atmospheric CO₂ content causes this process to terminate prematurely. Thus, CO₂ is able to regulate bacterial adaptive reactions and is probably one of the signals involved in the initiation and termination of the process of adaptive proliferation. It was shown that CO₂ in the form of the bicarbonate ion \({\text{HCO}}_{3}^{ - }\) can activate the cAMP-dependent signaling cascade and is also included in the bacterial cell mass.