Bioremediation of oil-contaminated sediment by hydrocarbonoclastic bacterial consortium immobilized in different types of carrier

Conventional bioremediation using free cells has been proven to be effective for oil spills management in the marine environment. However, there are some drawbacks to this conventional technique such as the decrease of cell concentration due to washing out by the ocean’s wave or current. Cell immobilization techniques can increase cells’ metabolic activities, increase cells’ resistance towards stress, and make the cells reusable. To explore a suitable carrier for oil bioremediation in the coastal environment, we tested the effectiveness of four different carriers for a consortium of hydrocarbonoclastic bacteria isolated from Jakarta Bay Ports. Entrapment was employed as the immobilization method and freeze-drying method was used to preserve the immobilized cells system. This experiment was carried out in microcosms as beach simulators for 28 days. Samples were analyzed for various variables such as total petroleum hydrocarbons (TPH), bacterial density, and environmental changes including pH, temperature, dissolved oxygen, and salinity. The control groups in this experiment were a group with no treatment and a group with free cell culture. The result showed that the effectiveness of immobilized cells in degrading oil in perlite, vermiculite, zeolite, and silica were not significantly different compared to free cells. Oil degradation activity by immobilized cells was observed in the range of 90.49–93.28% after 28 days of observation time. Perlite-immobilized bacterial consortium showed the highest oil degradation activity of 93.28%. Based on our results, we propose perlite as the most suitable carrier for crude oil bioremediation purposes.