Abstract:
Bacterial consortium SJ42 isolated from morning glory root could completely degrade 1% diesel in liquid medium within 7 days. SJ42 composed of at least 3 pure bacterial isolates. Morphological characteristics, biochemical reaction and 16S rDNA nucleotide sequence analyses revealed that those strains are Pseudomonas aeruginosa S4A, Stenotrophomonas maltophilia S4B and Ochrobactrum intermedium S4C. P. aeruginosa S4A could degrade 63.30±1.97% of diesel within 14 days whereas S. maltophilia S4B and O. intermedium S4C could not utilize diesel as sole carbon source for growth. Before cell immobilization, indigenous microorganisms on water hyacinth (Eichhornia crassipes) roots were decontaminated by immersion roots into 2% sodium hypochlorite solution together with sonication for 20 min which could reduce 53.81% of root bacteria. SJ42 was immobilized on water hyacinth roots by immersion in bacteria solution for 24 hours. After immobilization, the bacterial cells were as high as 10.32±0.15 log CFU/gram root. Scanning electron micrograph (SEM) as well as 16S rDNA PCR-DGGE analyzes showed that SJ42 attached on water hyacinth roots. Water hyacinth with immobilized SJ42 could reduce 1% diesel in Chao Phraya freshwater samples to the highest of 81.11±0.91% within 7 days whereas natural water hyacinth and planktonic SJ42 could remove only 33.99±4.41% and 31.48±8.1%, respectively which was not significantly different from control experiment (31.39±8.58%) This research proposed a successful method to immobilize a bacterial consortium SJ42 onto water hyacinth roots and plant root-bacterial association enhanced the diesel removal better than the utilization of planktonic bacteria or plant alone.