Variation of bacterial community immobilized in polyethylene glycol carrier during mineralization of xenobiotics analyzed by TGGE technique

Abstract

Acinetobacter sp. SMIC-1, Cupriavidus sp. SMIC-2, Pseudomonas sp. SMIC-3, Paracoccus sp. SMIC-4, and Pseudomonas sp. SMIC-5 capable of mineralizing xenobiotics (manmade organic compounds) that are diethyleneglycol monomethyleher (DGMME), 1-amino-2-propanol (APOL), 1-methyl-2-pyrrolidinone (NMP), diethyleneglycol monoethylether (DGMEE), tetraethyleneglycol (TEG) and tetrahydrothiophene 1,1-dioxide (Sulfolane) were immobilized mixedly in polyethyleneglycol carrier (SMIC-PEG). TGGE technique was employed to analyze variation of the immobilized bacterial community during xenobiotics being mineralized. The SMIC-PEG mineralized more than 95% of the xenobiotics except sulfolane in 6 days. When activated sludge (AS) was co-immobilized with SMIC community in PEG carrier (AS-SMIC-PEG), degradation efficiency of DGMEE, NPM was a little decreased; however, the degradation of other xenobiotics was neither increased nor decreased significantly. The bacterial community diversity in the SMIC-PEG was gradually decreased in proportion to incubation time in a batch cultivation reactor. SMIC strains in AS-SMIC-PEG were substituted by other bacterial community after 6 days of incubation time in batch cultivation reactor. The SMIC-PEG mineralized around 90% of xenobiotics in a continuous pilot reactor when 100 or 200 mg/L of xenobiotics was fed for 8 hr of hydraulic retention time (HRT); however, the mineralization efficiency was decreased significantly to around 75% when 200 mg/L of xenobiotics was fed for 4 hr of HRT. The mineralization effect of AS-SMIC-PEG for xenobiotics was lower than SMIC-PEG Bacterial community diversity in both SMIC-PEG and AS-SMIC-EG was decreased in proportion to operation time in the continuous pilot reactor; however, some of them were maintained during operation for more than 50 days.