Effects Of Ammonia And Nitrate Nitrogen On Cr (â…¥) Reduction Abiliity And Genome Sequence Analysis Of Serratia SP.S2

Objective:To study the effect of Cr (VI) reduction ability of Serratia sp. S2 under ammonia nitrogen (NH3-N) or/and nitrate nitrogen (NO3-N). Analyse the genome sequence of S2 and possible mechanism at the molecular lever.Methods:Domesticated and cultivated S2 containing Cr(Ⅵ) of different concentrations to get the Cr (VI) resistant strains. Simulated the nitrogen pollution of common environment in the laboratory and added different doses of NH3-N and/or NO3-N to the cultivation system in order to different types and concentrations of nitrogen. Shaked culture at constant 37℃ and measured A600, Cr(VI) removal rate, the amount of NH3-N, NO2-N, NO3-N of the cultivation system at a regular intervals. DNA of S2 was extracted. Determinated the genome sequence of S2, analysed related genes and discussed possible mechansim.Results:The growth inhibition of Cr(VI) to S2 was remittenced under the low and middle concentration of NH3-N. The decline of S2 was accelerated under the high concentration of NO3-N and NH3-N. The removal rate of Cr (Ⅵ) and amount of NH3-N among experience and control groups according to the independent effect of NH3-N had no significant difference. The removal rate of Cr (VI) of low concentration groups had a reduction of 10.7%-13.8%(P<0.05) and a increase of 7.1% (P<0.05) according to the independent effect of NO3-N. S2 had the ability to reduce 200mg/l NO3-N to the level of control groups. While NH3-N and NO3-N effect at the same time, NH3-N played a leading role in low concentration groups and NO3-N in high concentration groups during the course of Cr (VI) reduction. Genetic sequence of S2 was got by gene sequencing and it contained several kinds of nitrate reductase, nitrite reductase, regulatory factor, transport protein and so on.Conclusion:The presence of NH3-N had no significant effect to the Cr (VI)-removal ability. Different concentrations of NO3-N had different effect to Cr (VI)-removal ability, high concentration NO3-N groups had an advantage effect, on the other hand, S2 had a significant ability of reducing NO3-N. There were several kinds of nitrate reductase and nitrite reductase which could make the co-governance of Cr (Ⅵ) and NO3-N come true.