T The complexity of diesel oil hydrocarbons chains makes diesel oil pollution in thesoil difficult to decompose and is classified as a priority pollutant. This study aimsto 1) determine the growth response of Lactobacillus fermentum bacteria andDekkera bruxellensis fungi in soil polluted with diesel oil; 2) determine theoptimum environmental conditions namely temperature, contact time and microbialconcentration to degrade Total Petroleum Hydrocarbon (TPH); 3) determine thehighest degradation efficiency in diesel oil. The degradation test of diesel oil wascarried out in artificial liquid media Stone Mineral Salt Solution (SMSS) and soilsolid media with controlled environmental conditions using a limited system (batchculture). Variations of stimulus applied to SMSS liquid media are temperaturevalues (°C) 25, 30, 35; contact time (days) 7, 14, 21 and microbial concentration(%) 5, 10, 15. In the soil medium applied the same variation in microbialconcentration. The degradation efficiency of TPH is carried out gravimetrically,while to detect organic compounds, analysis is carried out with GasChromatography-Flame Ionization Detector (GC-FID). All samples were incubatedusing a shaker incubator with a rotating speed of 150 rpm and pH 7. The results ofthe microbial growth response show that microbes are able to grow and are resistantto 10% diesel oil. The optimum conditions for degrading TPH in SMSS artificialliquid media are 30ºC temperature and 14 days contact time with TPH degradationefficiency of 94.32%. In soil media polluted with diesel oil, the addition of 15%microbes to sterile soils, 5% to non-sterile soils and without exogenous microbesresulted in degradation efficiencies of 94.62%, 92.85% and 9.8% respectively. Thedegradation efficiency value is supported by the results of - analysis, namely thereduction of the Carbon (C) atomic chain before and after degradation. The kineticsof the rate of degradation is most appropriate using the Monod equation of order 2with the value R2=1.00. The pilot scale design was carried out assuming 250 m3ofdiesel oil-polluted soil required 60,830,153 L of microbial mixed culture with adegradation time of 133 days. This proves that microbes are able to degrade TPHof diesel oil under controlled environmental conditions. The existence of thisresearch has a very positive impact and can be an effective and efficient alternativein dealing with cases of soil polluted with diesel oil in the environment.