Figure 1: Dynamics of the microbial growth as a function of oil concentration in the presence of co-substrate and drilling fluid (▲) and in the media containing only drilling fluid(■). Cp: the peak concentration as the concentration of drilling fluid, which provides maximum growth rate: MSC: the minimum suppressive concentration of drilling fluid, which reduces microbial growth rate compared to control drilling fluid-free media; MIC: the minimum inhibitory concentration (MIC) corresponding to the minimum drilling fluid concentration needed to stop microbial growth; MBC: the minimum bactericidal concentration (MBC) as a minimum concentration of drilling fluid resulting in 99.9% microbial population kill.