The invention relates to the technical field of
water body nitrate pollution treatment and control, and is a method for culturing a denitrifying bacterium and using the bacterium to determine
water body nitrate nitrogen isotopic composition. The method comprises the following steps of: (1) carrying out
enrichment culture of the
denitrifying bacteria, (2) detecting whether the
denitrifying bacteria completely converse NO3- in a
culture fluid, (3) concentrating of the
denitrifying bacteria, (4) adding the concentrated
cell culture to a sample
bottle, purifying an upper space and removing N2O in the denitrifying bacterium liquid, (5) conversing NO3- in the sample to N2O, (6) determining the N2O
nitrogen isotope, and (7) correcting the
nitrogen isotope determination result to complete the test. The positive effects of the invention are as follows: the culture of the denitrifying
bacteria can be completed by using only a common
saline bottle or a triangular flask, the detection of
sulfanilamide color development improves the reliability of the determination result, and the determination cost is reduced. For the current situation that severe
water body nitrate pollution is urgently needed to be treated, the method of the invention has the advantages of scientificalness, simplicity, and high maneuverability, and has a broad popularization prospect.