Characterization of a mycobacterial cellulase and its impact on biofilm- and drug-induced cellulose production.

It was recently shown that Mycobacterium tuberculosis produces cellulose which forms an integral part of its extracellular polymeric substances within a biofilm set-up. Using Mycobacterium smegmatis as a proxy model organism, we demonstrate that M. smegmatis biofilms treated with purified MSMEG_6752 releases the main cellulose degradation-product (cellobiose), detected by using ionic chromatography, suggesting that MSMEG_6752 encodes a cellulase. Its overexpression in M. smegmatis prevents spontaneous biofilm formation. Moreover, the method reported here allowed detecting cellobiose when M. smegmatis cultures were exposed to a subinhibitory dose of rifampicin. Overall, this study highlights the role of the MSMEG_6752 in managing cellulose production induced during biofilm formation and antibiotic stress response.