Delineation of transcriptional regulators involve in biofilm formation cycle of Mycobacterium abscessus

Mycobacterium abscessus is an intrinsically and acquired multidrug resistant (MDR) intracellular pathogen with biofilm formation capability and limited option for treatment. Biofilm is the major characteristic that leads to failure and prolong treatment, intensifies treatment cost and increases mortality/morbidity rate. However, the biofilm formation regulations of M. abscessus remain largely unexplored. In this study, we identify the putative/ hypothetical transcriptional regulator (TR) of M. abscessus that are involved in biofilm formation. This study includes fifty TRs belonging to thirteen different families viz., AraC, ArsR, AsnC, CarD, CdaR, GntR, IclR, LysR, MarR, PadR, PrrA, TetR and WhiB, including TRs of unknown family. The promoter of these putative TRs were fused individually with GFP and analyzed their expression using CLSM in planktonic phase and early, mid and mature stages of biofilm formation phase, which overall termed as biofilm formation cycle. Further, qRT-PCR was carried out for selected TRs to analyze their differential expressions. This study found thirteen numbers of TR belonging to TetR family, five TRs belonging to MarR family, four TRs of unannotated TR family, two AraC TRs, two LysR, two GntR, two AsnC, one each of ArsR family, CarD family, IclR family, PadR family, PrrA family and WhiB family selected for this study are involved in biofilm formation cycle. Our study characterized the TRs with respect to their role in biofilm formation for the first time in M. abscessus and also found that their biofilm formation is regulated by diverse TR families.