Biofilm and pellicle formation under low and high nitrogen condition. A. M. bovis, wild type M. smegmatis and MSFP were grown 7H9 medium to form biofilm in low and high nitrogen medium. B. Biofilm formation assayed using the 1% crystal violet (CV) staining assay. Cells in low nitrogen (black bars), High nitrogen (crossed bars) and control (grey bars) in 7H9 media were grown in low and high nitrogen on polystyrene plates. The experiments were repeated three times with similar result. Control, medium only. C. Pellicle formation at the air-liquid interface of the standing 7H9 culture by strains M. bovis (i), M. smegmatis (ii) and MSFP (iii) in low and high nitrogen condition. Results are representative of at least three independent experiments. LN, low nitrogen; HN, high nitrogen.