Formation of Mycobacterial Pellicles In Vitro and their Possible Impact on Tuberculosis Infection

Studies about in vitro pellicle formation by slow-growing, pathogenic mycobacteria has just gained a new momentum, and in Mycobacterium tuberculosis, cells growing in this environment showed enhanced tolerance to antitubercular drugs. c-di-GMP, an ubiquitous bacterial second messenger, regulates phenotypes such as motility, biofilm formation and expression of acute virulence factors in several microorganisms. Recently, enzymes encoded by Rv1354c and Rv1357c were shown to produce and degrade c-di-GMP in vitro, respectively. Here we review the processes in which c-di-GMP regulates biofilm production and virulence in some human pathogens, discuss the possibility of these same processes existing in Mycobacterium tuberculosis, and how these mechanisms could impact the outcome of tuberculosis infection.