Growth of the mycobacterial strains in low and high nitrogen broth culture. A. OD600 of wild type M. bovis was inoculated to an initial optical density of 0.006 - 0.008 in 7H9 medium containing (●) low nitrogen (3.8 mM ammonium sulphate) and (▲) high nitrogen (60 mM ammonium sulphate). B. OD600 of wild type M. smegmatis and MSFP in low and high nitrogen broth culture. Wild type M. smegmatis, low nitrogen (■), high nitrogen (□); MSFP, low nitrogen (●), high nitrogen (○). Data is mean ± SD of values obtained from three independent cultures. LN, low nitrogen; HN, high nitrogen.