The production of N-nitrosoiminodiacetate from nitrilotriacetate and nitrate by microorganisms growing in mixed culture

Mixed populations of microorganisms growing in a recycling soil percolator produced N-nitrosoiminodiacetate (NIDA) after 30 days growth using sodium nitrilotriacetate (NTA), a detergent additive, and NaNO₃ as C and N source respectively. Control experiments using autoclaved soil or substituting either acetate (C source) or NH⁺₄ (N source) did not show any N-nitroso derivative production. Five distinct strains of microorganisms were isolated which could grow on an NTA/NO^?₃ minimal medium but none produced NIDA in pure culture. Mixed cultures of two strains of Pseudomonas produced NIDA after 4 days percolation, using glass beads as a support. Cell-free extracts of the mixed cultures synthesized NIDA after 30 min incubation at 30°C with an activity of 27 μmoles NIDA produced/mg protein h^?1. Physical separation of the two organisms and the cell-free extracts by a dialysis membrane in a chamber determined that only one of the two organisms was responsible for the synthesis of NIDA, but the production was dependent upon the presence of the other organism. The possible relationship between the two organisms is discussed.