Integrating kinetic models, gene circuits, and biofilm dynamics for enhanced exopolysaccharide production in...

Bacterial consortia enriched from domestic wastewater were studied through kinetic and genetic circuit modelling to optimize extracellular polysaccharide (EPS) production and nitrogen removal. This study integrates kinetic modelling and synthetic biology to optimize consortia performance. Growth kinetics were simulated using extended Monod and Verhulst models, under controlled nitrogen flux (10 ppm NH₄Cl), yielding a maximum biomass concentration (OD₅₉₀ = 5.39) and an EPS production of 2.63 g/L by day 45. The Monod model described the specific growth rate (μ) as a function of nitrogen concentration (Sₙ), while the Verhulst model estimated biomass accumulation over time. Scanning electron microscopy (SEM) showed the gradual development of biofilms, starting from scattered clusters, and progressing to dense structures. Nitrogen flux analysis revealed that 80 % of ammonia was oxidized by nitrifying bacterial population. PCR amplification confirmed the presence of the exoY gene, which was used to build a BUFFER-gate logic gene circuit for controlling succinoglycan production. Through focused genetic and kinetic optimization, this study demonstrates effective nitrification, providing a strong framework for wastewater treatment and biofilm engineering.