Isolation and Identification of Oil-Degrading and Lead-Bioaccumulating Bacteria and their Degree of Degradation/Bioaccumulation in Coaco Harbor, Sasa, Davao City

Mary G Barluado, Vill Patrick M de Leon, Rae Kristine E Desabelle, May Amor C Gadayan, Anthony B Pascasio, Elisa B Bacus


Hydrocarbons like diesel oil and heavy metals like lead are known water pollutants posing serious damage to marine life. The potential use of microorganisms to remediate water environmental problems is considered a cost-effective large scale solution. Oil-degrading and lead-bioaccumulating bacteria may thrive in environments exposed to the mentioned pollutants. The study attempted to isolate and identify bacterial strain that can both degrade hydrocarbons and bioabsorb heavy metals. Water samples collected near ship refuelling site in Coaco harbor were inoculated onto Bushnel Haas Agar (BHA) and produced growth of five organisms with oil-degrading potential. They were then isolated, subjected to biochemical tests, and identitied to be Escherichia sp., Micrococcus sp., Citrobacter amalonaticus, Enterobacter agglomerans, Citrobacter freundii. They were then used to treat diesel oil-contaminated water, and the degree of oil degradation was determined by measuring the oil concentration in the treated samples through Liquid-Liquid Partition Gravimetric Method. Of the five isolates, Citrobacter amalonaticus, Enterobacter agglomerans and Citrobacter freundii have shown significant ability to degrade oil contaminants in test samples, with Citrobacter freundii exhibiting the highest capacity. The isolated oil-degrading organisms were then used to treat lead-contaminated water to determine their lead-bioaccumulating capacity, which was analyed by determining the remaining lead concentration in the water media measured by Direct Air Acetylene Flame method. Results clearly indicated that the five bacterial isolates showed substantial ability to absorb soluble lead with Citrobacter freundii exhibiting the highest ability in lead absorption, showing significant difference (p<0.05) as compared with the negative control and the rest of the isolates. Thus, the study successfully isolated and identified organisms with both oil-degrading and lead-bioabsorbing capabilities, with Citrobacter freundii isolate consistently exhibiting the highest ability, making it an excellent subject for use in future bioremediation studies.

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