Three-dimensional low shear culture of Mycobacterium bovis BCG induces biofilm formation and antimicrobial drug tolerance

ABSTRACT: Mycobacteria naturally grow as corded biofilms in liquid media without detergent. Such detergent-free biofilm phenotypes may reflect the growth pattern of bacilli in tuberculous lung lesions. New strategies are required to treat tuberculosis that is responsible for more deaths each year than any other bacterial disease. The lengthy six-month regimen for drug-sensitive tuberculosis is necessary to remove antimicrobial drug tolerant populations of bacilli that persist through drug therapy. The role of biofilm-like growth in the generation of these sub-populations remains poorly understood despite the hypothesized clinical significance and mounting evidence of biofilms in pathogenesis. We adapted a three-dimensional Rotary Cell Culture System to model M. bovis BCG biofilm growth in low-shear detergent-free liquid suspension. Importantly, biofilms formed without attachment to artificial surfaces and without severe nutrient starvation or environmental stress. Biofilm-derived planktonic bacilli were tolerant to isoniazid and streptomycin, but not rifampicin. This phenotypic drug tolerance was lost after passage in drug-free media. Transcriptional profiling revealed induction of cell surface regulators, sigE and BCG_0559c alongside the ESX-5 secretion apparatus in these low-shear liquid-suspension biofilms. Supernatant from biofilms induced greater pro-inflammatory cytokine release from macrophages. This study engineers and characterizes mycobacteria grown as a suspended biofilm, illuminating new drug discovery pathways for this deadly disease.

ORGANISM(S): Mycobacterium tuberculosis variant bovis BCG str. Pasteur 1173P2

SUBMITTER: Simon Waddell 

PROVIDER: E-MTAB-9904 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress