Screening of Used Engine Oil degrading Bacteria by 2-6 DCPIP Assay

Abstract

Lubricating engine oil which is used in vehicles and machines to keep them running smoothly, is frequently released during automobile engine servicing or illegally dumped, posing a significant environmental threat because it is less volatile than other types of petroleum fuels and remains in the soil for longer periods of time. To solve this problem, new environmentally friendly techniques must be created. Considering the same, the current investigation, was carried out to screen and evaluate the oil-degrading capability of bacterial isolates from oil-contaminated soil collected from different sites of Udaipur city. The isolation was done on Luria-Bertani agar using the pour plate method. The primary screening of the isolates for used engine oil degradation was done on Bushnell Haas mineral salt agar medium using the spot inoculation method. The 2,6-DCPIP (2,6-Dichlorophenol indophenol) indicator was used to determine the oil degrading efficiency of isolates. A total of ten soil samples contaminated with used engine oil were collected from two distinct locations of Udaipur city. A total of seventy eight bacterial isolates were recovered using pour plate method from various soil samples on LB (Luria-Bertani) agar at 370C after 24 hours of incubation period. Twelve bacterial isolates out of seventy eight showed zone of clearance, indicating oil degrading capability. The diameter for zone of clearance of 12 isolates ranged between 5 to 15 mm. All 12 isolates demonstrated DCPIP decolorization. Color reduction percentage ranged from 68.66 % to 98.57 % for 12 oil-degrading bacterial isolates. Isolate ODB 29 showed the highest color reduction (98.57 %). These isolates may be explored for their possible use in bioremediation.