Mycobacterium abscessus cultured in SCFM with heme treatment.

Mycobacterium abscessus (Mabs) biofilms are altered in the presence of exogenous heme. We wanted to determine how protein levels were affected by heme. Mabs cells were grown in a modified media formulated to mimic the nutritional environment of the sputum of cystic fibrosis (CF) patients. Mabs cells grown in synthetic CF media (SCFM) typically form submerged biofilms, exogenous heme treatment however prevents this film formation and supports growth of a pellicle at the air-liquid interface. Heme treatment reduced several iron uptake and homeostasis proteins, suggesting heme is acting as an iron source for these bacteria. In addition, multiple proteins were upregulated in heme treatment, however, the function of these proteins remains to be determined.