Antonie van Leeuwenhoek

, Volume 104, Issue 5, pp 725–735 | Cite as

Pili contribute to biofilm formation in vitro in Mycobacterium tuberculosis

  • Saiyur Ramsugit
  • Sinenhlanhla Guma
  • Balakrishna Pillay
  • Paras Jain
  • Michelle H. Larsen
  • Siva Danaviah
  • Manormoney PillayEmail author
Original Paper


Organized bacterial communities, or biofilms, provide an important reservoir for persistent cells that are inaccessible or tolerant to antibiotics. Curli pili are cell-surface structures produced by certain bacteria and have been implicated in biofilm formation in these species. In order to determine whether these structures, which were suggested to be encoded by the Rv3312A (mtp) gene, have a similar role in Mycobacterium tuberculosis, we generated a Δmtp mutant and a mtp-complemented strain of a clinical isolate of M. tuberculosis and analyzed these strains for their ability to produce pili in comparison to the wild-type strain. Phenotypic analysis by transmission electron microscopy proved the essentiality of mtp for piliation in M. tuberculosis. We then compared biofilm formation of the derived strains in detergent-free Sauton’s media. Biofilm mass was quantified spectrophotometrically using crystal violet. Furthermore, we examined mtp gene expression by quantitative real-time PCR in wild-type cells grown under biofilm versus planktonic growth conditions. We found a 68.4 % reduction in biofilm mass in the mutant compared to the wild-type strain (P = 0.002). Complementation of the mutant resulted in a restoration of the wild-type biofilm phenotype (P = 0.022). We, however, found no significant difference between mtp expression in cells of the biofilm to those growing planktonically. Our findings highlight a crucial, but non-specific, role of pili in the biofilm lifestyle of M. tuberculosis and indicate that they may represent an important target for the development of therapeutics to attenuate biofilm formation, thereby potentially reducing persistence.


Mycobacterium tuberculosis Curli pili Gene deletion Complementation Adhesin Persistence 



We thank Mr Mhlengi Vella Ncube (UKZN) for his contribution to the generation of the Δmtp mutant; Ms Charissa Naidoo (UKZN) for help with the statistical analysis; and the National Research Foundation (NRF), SA, Medical Research Council (MRC), SA, and College of Health Sciences (CHS), UKZN, for financial support. Mr S. Ramsugit gratefully acknowledges scholarship from the NRF and Canon Collins Trust.

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Saiyur Ramsugit
    • 1
  • Sinenhlanhla Guma
    • 2
  • Balakrishna Pillay
    • 2
  • Paras Jain
    • 3
    • 4
  • Michelle H. Larsen
    • 4
    • 5
  • Siva Danaviah
    • 6
  • Manormoney Pillay
    • 1
    Email author
  1. 1.Medical Microbiology and Infection Control, School of Laboratory Medicine and Medical Sciences, College of Health SciencesUniversity of KwaZulu-NatalDurbanSouth Africa
  2. 2.MicrobiologyUniversity of KwaZulu-NatalDurbanSouth Africa
  3. 3.Department of Microbiology and ImmunologyAlbert Einstein College of MedicineNew YorkUSA
  4. 4.Howard Hughes Medical InstituteAlbert Einstein College of MedicineNew YorkUSA
  5. 5.Department of MedicineAlbert Einstein College of MedicineNew YorkUSA
  6. 6.Africa Centre for Health and Population StudiesUniversity of KwaZulu-NatalDurbanSouth Africa

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