Study On Screening And Degradation Characteristic Of A N,N-Dimethyl Ethanolamine Degrading Bacteria L2 And Its Cell Immobilization

In this study, a efficiency N,N-dimethyl ethanolamine degrading strain was isolated fromchemical factory wastewater treatment pool. This strain could use N,N-dimethyl ethanolamine as the sole carbonand nitrogen source for growth, and be named as L2. The strain L2 could be identified as Pseudomonas sp. on the base of its physiological and biochemical properties, and united with its 16S rRNA gene sequence analysis.The strain L2 grew fast in mineral liquid medium of N,N-dimethyl ethanolamine. After 8h’s cultivation, bacteria entered into the logarithmic growth period and 18～28 h was the stable growth period. The optimum temperature was 30℃, and the best pH was 8.0. When the pH was 6.0～8.0, the strain could grow well; The impact of ventilation was rarely on the growth of the strain L2, but the concentration of NaCl had great influence on the growth of stain L2. When the concentration of NaCl was 0～5 g·L-1, the strains could grow better, and the growth of strains are inhibited in NaCl solution with concentration in the range of 10～30 g·L-1. In all carbon sources, the strain L2 had the highest utilize efficiency in glucose and in all the nitrogen sources, the machine nitrogen source of urea and peptone, the inorganic nitrogen of ammonium sulfate possessed the higher efficiency of utilization respectively comparing to others carbon and nitrogen sources.Results of the degradation characteristic of the strain L2 showed that the optimum degradation pH was 6.0～8.0 and the best temperature was 30℃. At the same time, with the increasing of the concentration of the N,N-dimethyl ethanolamine, its degradation concentration by strains will also increased. Improving inoculation rate speeded up the degradation of N,N-dimethyl ethanolamine. When the inoculation amount is 4% and 8%, the N,N-dimethyl ethanolamine are fully degraded after 24 hours; Ventilation hadlittle effect on the degradation of N,N-dimethyl ethanolamine.This study usesodium alginateembedding method to investigate the immobilization conditions for degrading strain L2. The results indicated that the mechanical property of immobilized pellets and the efficiency for degradation of N,N-dimethyl ethanolamine were the best when the concentration of sodium alginate was 3%. And, the concentration of CaCl2 was 3% the immobilized time was 15 h and the packet bacteria were 2.0 g·L-1. The degradation rate of immobilized bacteria was slower than the free bacteria, but immobilized bacteria could tolerate pH and temperature in a wider range.