Degradation of crude oil-degrading bacteria isolated from the coastal waters of Bengkalis Island, Riau

Abstract

Bengkalis waters is relatively busy traffic area due to regional and international marine transportation which is very vulnerable to oil pollution. Cleaning of oil spill could be attempted by the use microorganisms (bioremediation). Bioremediation is an effective, economical and environmentally friendly treatment method in which microbes are used to degrade hydrocarbons. The objectives of this research were to isolate oil-degrading bacteria from seawaters in the North coast and in the South area of Bengkalis Island, to examine the bacterial isolates in degrading crude oil and to identify the isolates by phenotype (morphological observation, biochemical tests) and genotype characters (16S rDNA sequence). Bacteria was isolated on SMSS basal medium, oil content was measured by Gravimetry method, DNA sequence was analized by using polymerase chain reaction (PCR) followed by sequencing using genetic analyzer machine. Sixteen bacterial isolates from the seawaters had different morphology, physical and biochemical characters. Six isolates from the North coastal waters (BM 1a, BM 1c, BM 1d, BM 7a, BM 14a and BM 14b) and three isolates from Sungai Pakning waters (S1P26B, S2P35b and S3P35a) showed high ability in degrading crude oil at concentrations 1%, 2% and 3%). DNA sequence analysis indicated isolate BM 1a had similarity to Bacillus circulan W239 (99%), isolate BM 1c was similar to B. thungiriensis LDC507 (92%), isolate BM 1d was similar to B. flexus CORSS01 (96%), isolates BM 7a and S1P26B were similar to B. cereus MBGIPS 18 (94% and 95%, respectively), isolate BM 14a was similar to B. flexus MDLD1 (, isolate BM 14b was similar to B. thuringiensis LDC 507 (98%), isolate S2P3 5b was similar to B. cereus KJW1 (98%) and isolate S3P3 5a was similar to B. cereus MCCC1a06185 (99%). In conclusion, bacteria of genus Bacillus dominated the crude-oil degrading bacteria from Bengkalis Island waters.