Isolation Of A N,N-Dimethylacetamide-Degrading Bacterium And Its Degradation Characteristics

N,N-Dimethylacetamide (DMAC) is an important chemical material and solent persisting good properties which is wildly used in polyurethane, acrylic fibers, medicines,pesticides, dye and electron industries. DMAC has certain toxic and is harmful to environment and people’s healthy which are difficultly to be degraded.A highly efficient N,N-Dimethylacetamide degrading strain was isolated from pesticide wastewater treatment pool. This strain could use DMAC as the sole source of carbon, nitrogen for its growth. It was identified as rhodococus rubber sp. according to its physiological and biochemical properties, and 16S rRNA gene sequence analysis. The strain was designated as DL-1.Through studying the growth characteristics of strain DL-1, the optimum growth temperature was 30℃ and in 25～35℃, the strain can grow well while both low and high temperatures could inhibit the growth. The strain could grow well in initial at pH 6.0～9.0 and the best pH was 8.0. By changing the liquid volume in the flask, it was found that ventilation had little effect on the growth of the strain. The concentration of NaCl had great impact on the growth of stain DL-1 and when the concentration of NaCl was 0～5 g/L, the strain grew best.In the study on degradation characteristics of DMAC by strain DL-1, results showed that when the inoculation rate was 1%, the concentration of DMAC was 500mg·L-1, the degradation efficiency of DMAC could reach 99% in salts liquid medium after 24h by strain DL-1. The strain has the best DMAC degradation efficiency at 30℃ and pH 8.0. Improving inoculation amount and will speeded up the degradation of DMAC and the if initial concentration of DMAC is too high, the drgradation will be affected.Using sodium alginate in embedding the DMAC degrading strain DL-1, results from investigations on experimental conditions and environmental factors showed that mechanical strength of immobilized beads were the best and the degradation of DMAC effect was the best when the concentration of sodium alginate was 3%, the concentration of CaCl2 being 2% and immobilized time was 12h.The degradation efficiency of immobilized bacteria was slower than the free bacteria, but immobilized bacteria could tolerance pH and temperature in a wider range.