Nanoenhanced Bacterial Stimulation of <i>Rhodococcus jostii</i> RHA1: A New Pathway for Sustainable Degradation of Phthalate in Complex Water Matrices

Bioremediation offers a promising and eco-friendly solution for the degradation of emerging contaminants; however, its field-scale application is constrained by the availability of essential nutrients and environmental variability. Here, we present a nutrient-activated biodegradation platform using engineered nanophosphates to stimulate the growth of Rhodococcus jostii RHA1 and enhance bacterial degradation of phthalate under nutrient-deficient conditions. The synthesized nanophosphates, composed of struvite/dittmarite phases, exhibited high crystallinity and were enriched with macronutrients (P, Mg, Ca) and trace metals (Fe, Mn, Zn, Cu, Co). Supplementation of 200 mg/L nanophosphate-supported rapid bacterial proliferation (biomass up to 92.8 mg/L) of R. jostii RHA1 and near-complete degradation of phthalate (100 mg/L) even in minimal or oligotrophic conditions within 3 h in diverse water matrices, using nanophosphates alone. No lag phase was observed in biomass growth or degradation kinetics, as modeled effectively by the Verhulst equation (R2 > 0.95) across higher phthalate loads (20–100 mg/L), confirming continuous nutrient release and persistent biostimulation. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) analyses further confirmed bacterial colonization, particle dissolution, and dynamic nutrient mobilization. The findings highlight the dual role of nanophosphates as nutrient reservoirs and stimulants for pollutant-degrading microbes, offering a scalable, low-input solution for remediating aromatic contaminants.