Purpose: The objective of this study was to elucidate if Pseudomonas spp. reduce sodium nitrite reduction and to analyze the gene related to sodium nitrite reduction.
Methods: A mixture of Pseudomonas aeruginosa (NCCP10250, NCCP10338, and NCCP11229) and a mixture of Pseudomonas fluorescens (KACC10326 and KACC10323) were incubated in nutrient broth (NB) plus 120 ppm sodium nitrite at 15°C for 216h. Residual sodium nitrite (ppm) in NB was calculated by diazotization reaction every 24h. After P.aeruginosa was identified for sodium nitrite reduction, transcriptome was analyzed by quantitative real-time PCR (qRT-PCR) to identify the sodium nitrite reductase gene for each P. aeruginosa strain.
Results: P. aeruginosa significantly decreased (P < 0.05) sodium nitrite concentration from 70 ppm to 0 ppm in NB after 168h of incubation, but P. fluorescens did not decrease sodium nitrite concentration compared to control (only sodium nitrite in NB). qRT-PCR analysis for three strains of P. aeruginosa strain showed that nirS, norC, nosF, and nosZ genes (sodium nitrite reductase gene) were expressed higher in NB plus 120 ppm sodium nitrite than that of control.
Significance: This result indicates that P. aeruginosa growth in processed meat products may allow foodborne pathogen growth by reducing sodium nitrite in the products.