Isolation of bacterial consortium from aquatic plant roots and immobilization on cockle shell and water mimosa sponge for bioremediation of diesel-contaminated water
Abstract:
Bacterial consortium TS1 was isolated from water hyacinth roots (Eichhornia crassipes), collected from diesel-contaminated fresh water. TS1 could utilize 84.78% of 1% diesel within 7 days. TS1 was immobilized on cockle shells and water mimosa sponges by adsorption method. Scanning electron microscope (SEM) revealed bacterial cells attached on the surface of shells and water mimosa sponges. The shell and water mimosa sponges immobilized cells could degrade 1% diesel 97.05% and 96.26% within 7 days, respectively. PCR-DGGE showed that TS1 was present on both carriers as well as in culture media. The sterile shells and water mimosa sponges could absorb diesel 30% and 70%, respectively. After 7 days, water mimosa sponges were decomposed but shells were not biodegradable. Factor affecting immobilization and diesel degradation revealed that the optimum of initial cell concentration, immobilization time and cockle shell size were 6 log CFU/mL for 30 minutes and 5x5 millimeter, respectively. The immobilized cell could degrade 1%, 3% and 5% diesel in liquid medium significantly more than free cells and could be reused more than 5 cycles. The immobilized cells kept in plastic zip lock bag at 4OC for 2 months remained active for diesel degradation. Moreover, the immobilized cell could degrade 1% diesel in liquid media which was 20-fold of shell weight. TS1 consisted of Pseudomonas aeruginosa, Stenotrophomonas sp., Ochrobactrum sp., Microbacterium sp., Shinella sp., Pusillimonas sp. and Pseudomonas sp. Individual bacterial strains were significantly less capable of diesel degradation than bacterial consortium TS1.