NAP enzyme recruitment in simultaneous bioremediation and nanoparticles synthesis

Our study aims to exploit the denitrifying bacteria MMT and its NAP enzyme in dual missions, nitrate removal from wastewater and nanoparticles synthesis. Therefore, the crud NAP enzyme was characterized and immobilized by entrapment technique for aforementioned application. To the best of author knowledge, the immobilization for denitrifying bacteria and NAP enzyme for simultaneous bioremediation and bionanoparticles synthesis was not studied previously. [Display omitted] •This study employed the immobilized strain MMT and its NAP enzyme in concurrent denitrification and NPs synthesis.•The properties of crude NAP enzyme were assessed at different ranges of pH and temperatures and also its stability at 4 °C and 30 °C was studied.•The effect of several types of additives were evaluated at concentration rang (1 mM, 2.5 mM, 5 mM and 10 mM).•Concurrently, the immobilized MMT cells completely removed NO3− upon 8th day with AgNPs synthesis ranging from 23.26 to 58.14.•Immobilized NAP exhibited lower efficiency with 28.6% of NO3 elimination and large aggregated AgNPs ranging from 94.44 nm to 172.22 nm. The periplasmic nitrate reductase enzyme (NAP) has become attractive catalyst, whose exploitation has emerged as one of the indispensable strategies toward environmentally benign applications. To achieve them efficiently and overcome the sensitivity of NAP in harsh environmental circumstances, the immobilization for denitrifying bacteria and NAP enzyme for simultaneous bioremediation and bionanoparticles synthesis was studied. NAP catalyzed NO3− reduction at Vmax of 0.811 μM/min and Km of 14.02 mM. Concurrently, the immobilized MMT cells completely removed NO3- upon 192 h with AgNPs synthesis ranging from 23.26 to 58.14 nm as indicated by SEM. Wherase, immobilized NAP exhibited lower efficiency with 28.6% of NO3− elimination within 288 h and large aggregated AgNPs ranging from 94.44 nm to 172.22 nm. To the best of author knowledge, the immobilization for denitrifying bacteria and NAP enzyme for simultaneous bioremediation and bionanoparticles synthesis was not studied before.