Characterization of biofilm formation by Mycobacterium smegmatis during different environmental stress conditions: An in-vitro study

Abstract

Aim: In-vitro characterisation of biofilm produced by Mycobacterium smegmatis (M. smegmatis), a surrogate model for biofilm production by Mycobacteria, and to evaluate the impact of different environmental stress on mycobacterial growth and biofilm formation. Methodology: M. smegmatis biofilms were studied using tissue culture plate and tube adherence methods. Confocal Laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were used to study the 3D structure and surface morphology, respectively. Additionally, the effect of different environmental stress, such as the absence of essential ions, exposure to harsh environmental conditions, such as acidic environment or oxidative stress, on mycobacterial biofilm formation and mycobacterial growth was assessed. Results: All the exposures, except for carbon supplemented media had a detrimental effect on the number of viable counts and on biofilm formation by mycobacteria (p<0.001). Growth in low pH and oxidative stress was found to be maximum showing reduction by 98% when compared with control. Interpretation: Our findings present various environmental conditions that profoundly affect biofilm formation and thus, may find practical implications in future as effective mycobacterial control strategies having attributes of mycobacterial growth as well as biofilm inhibition. Key words: Biofilm, Environmental stress, Multi-drug resistance, Mycobacterium