Biodegradation of Crude Oil by Constructed Bacterial Consortia and the Constituent Single Bacteria Isolated From Malaysia

Three bacterial isolates identified as Pseudomonas aeruginosa (UKMP-8T), Rhodococcus sp. M15-2 (UKMP-5T), and Rhodococcus sp. ZH8 (UKMP-7T) based on biochemical, physiological, and morphological characteristics and on 16S rDNA sequences were isolated from groundwater of a crude oil refinery plant. From these three isolates, four bacterial consortia were designed by mixing the single bacterial cultures in the following ratios: (P. aeruginosa:Rhodococcus sp. M15-2, 1:1), (P. aeruginosa:Rhodococcus sp. ZH8, 1:1), (Rhodococcus sp. M15-2: Rhodococcus sp. ZH8, 1:1), and (P. aeruginosa: Rhodococcus sp. ZH8:Rhodococcus sp. M15-2, 1:1:1), respectively. Bacterial isolates and consortia showed differing preferences for nitrogen source (0.01% ammonium chloride, 0.10% yeast extract, or 0.50% peptone) to reach optimum growth. When fortified with the preferred nitrogen sources and grown in minimal salt medium, within 7 days all three single isolates and the four bacterial consortia biodegraded 97.6-99.9% of Tapis Massa oil without any significant differences.