Objective  To screen for a high-yielding nitrite reductase-producing strain, isolate and purify the enzyme produced, and study its enzymatic properties, thereby providing strain resources and experimental basis for the application of nitrite reductase in the food industry.

Methods A high-yielding nitrite reductase-producing strain was isolated from fermented sausages. The enzyme was purified through ammonium sulfate precipitation, dialysis, DEAE-52 cellulose anion-exchange chromatography, and Sephadex G-150 gel filtration. The molecular weight of the purified enzyme was determined by SDS-PAGE electrophoresis, and the enzyme type was preliminarily inferred. Single-factor experiments were conducted to optimize the production conditions of nitrite reductase by Pediococcus acidilactici A3, including temperature, pH, kinetic parameters, and the effects of inhibitors and activators on the enzymatic reaction.

Results Pediococcus acidilactici A3 was successfully screened and yielded highly purified nitrite reductase. SDS-PAGE analysis revealed a molecular weight of 63.83 kDa, suggesting that the enzyme is likely a cytochrome cd1-type nitrite reductase. The optimal conditions for enzyme production by Pediococcus acidilactici A3 were determined to be 35℃ and pH 6.0, with a K_m value of 43.6 mmol·L⁻¹. Metal ions and inhibitors significantly affected enzyme activity: Fe²⁺ and Fe³⁺ markedly enhanced activity, while Zn²⁺, K⁺, and EDTA exhibited inhibitory effects.

Conclusion This study successfully isolated Pediococcus acidilactici A3, a strain capable of producing high levels of nitrite reductase from fermented sausages. An effective purification protocol combining ammonium sulfate precipitation and chromatography was established, yielding cytochrome cd1-type nitrite reductase. The optimal enzyme production conditions and key enzymatic characteristics were clarified: Fe²⁺ and Fe³⁺ act as effective activators, whereas Zn²⁺, K⁺, and EDTA serve as inhibitors. The strain and its nitrite reductase show promising potential for application in the food industry, laying a foundation for future development and utilization of this enzyme.