Study On The MTBE Degradation By Microbes

A bacterial strain ofβ-Proteobacteria (PM1) that might utilize Methyl tert-Butyl Ether (MTBE) as sole carbon and energy resources was used to biodegrade MTBE. The efficiency of degradation was affected by culture conditions such as pH, initial cell concentration of the culture and the initial concentration of MTBE, it was determined that the optimum conditions were pH 7.2, initial cell concentration 10~7cells/mL and initial MTBE concentration 25mg/L. The effect of diluted oxygen (DO) of the medium in closed system on the degradation was also studied by one "cannula". The results showed supplied oxygen could promote the degradation.One wild-type plasmid in PM1 was exposed by electropherogram. To explore whether the plasmid carried degrading genes, it was transformed into E. coli JM109, eventually transformants did not obtain degrading ability; the other way, through elevating growth temperature, PM1 was cured the plasmid and that plasmid-free mutant was still able to degrade MTBE. Therefore, it was inferred that this plasmid didn't carry any degrading gene.Hexane and cyclohexane were selected as cometabolic substances to evaluate the effect of co-metabolism on MTBE degradation, the result suggested that hexane and cyclohexane could inhibit PM1 metabolism and no MTBE degradation was required for the metabolism and growth of PM1. Furthermore, research that PM1 was entrapped in sodium alginate indicated the immobilized cells decreased activity but broadened arrange of suitable temperature. Because of many merits, immobilized cells were fit for concerned research.The P&T GC-MS result of PM1 degradation system suggested that tert-butyl alcohol, isopropanol and acetone were the key intermediate products.One strain named SCL1 was isolated, which was judged as a strain of Pseudomonas sp. Its optimum degradation conditions were: temperature for degradation is 25℃, pH 6.8, initial cell concentration 10~6cells/mL-10~7cells/mL。Co-culture of Chlorella ellipsoidea and SCL1 suggested that, to some degree, the existence of Chlorella ellipsoidea could accelerate degradation of MTBE.