Jezzine Marie A. Arguelles, Mary Angelique H. Celiz, John Noel M. Viaña (March 2008)
Philippine Science High School Western Visayas Campus – Department of Science and Technology (DOST-PSHS WVC), Brgy. Bito-on, Jaro, Iloilo City 5000, Philippines
ABSTRACT
Diesel Oil has been considered one of the most acutely toxic oil types. Oil dispersed in open water can adhere to fine-grained suspended sediments and get deposited on the sea floor thus damaging the ecosystem and organisms in there. Biodegradation is the process in which organic substances are broken down by living organisms. Usually, the microorganisms use the hydrocarbons as their carbon source. Several species of bacteria have been found out by some studies to degrade diesel oil.
This study aims to determine the potential of pure cultures, co-cultures , and mixed cultures of Pseudomonas fluorescens, Psuedomonas putida and Pseudomonas stutzeri to degrade diesel.
The diesel oil in the microtiter plates were used as the carbon source of the bacteria in the microtiter plates containing Bushnell-Haas medium. In the study, the bacteria were first sub-cultured. Then, the bacterial dilutions were prepared. After which, the bacterial culture combinations were introduced in the microtiter plates. Each bacterial culture combination namely pure culture of Pseudomonas putida, pure culture of Pseudomonas fluorescens, pure culture of Pseudomonas stutzeri, co-culture of Pseudomonas putida and Pseudomonas fluorescens, co-culture of Pseudomonas putida and Pseudomonas stutzeri, co-culture of Pseudomonas fluorescens and Pseudomonas stutzeri, mixed culture of Pseudomonas putida, Pseudomonas fluorescens, and Pseudomonas stutzeri, and control were each designated three microtiter wells. After such, they were incubated for three weeks and were then subjected to physical examination for signs of the bacterial metabolism indicators namely change in color, change in amount of diesel oil left, and amount of water and Bushnell-Haas medium left.
Results of the study showed that all of the bacterial combinations exhibited color change. It also showed that almost all of the dilutions of pure cultures of P. putida and P. fluorescens, co-cultures of P. stutzeri, and P. fluorescens, and mixed culture of P. putida, P. fluorescens, and P. stutzeri, showed full evaporation of media. It also showed that no amount of diesel was left in the 10 negative 3 dilution of mixed culture of P. putida, P. stutzeri, and P. fluorescens, 10 dilution of pure culture of P. fluorescens, and 10 raise to negative 1 dilution of co-culture of P. stutzeri and P. fluorescens.
From the results obtained in the study, it can be concluded that only the mixed culture of P. putida, P. stutzeri and P. fluorescens, pure culture of P. fluorescens, and co-culture of P. stutzeri and P. fluorescens showed potential in degrading diesel oil.