Rapid acetate quantification via microbial electrochemical sensors: A temporal modeling approach with cross-strain validation.

Timely monitoring of volatile fatty acids (VFAs) is critical for maintaining in the stability in anaerobic digestion, however conventional chromatographic analyses delay actionable feedback. Microbial electrochemical sensors (MES) provide continuous electrical signals, yet it remains unclear how early these responses can support quantitative acetate prediction across independently operated systems and when electrochemical context becomes useful. This study investigated four strain-specific MES setups, i.e. Pseudomonas aeruginosa, Shewanella oneidensis MR-1, Bacillus subtilis, and Escherichia coli, over six acetate levels (0.1-10.0 mM). A temporal framework combining truncated voltage trajectories, eight kinetic summaries, and cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) descriptors were evaluated by nested grouped leave-one-strain-out validation. Cross-strain validation showed that acetate concentration could be quantified with R2 = 0.938 at 120 min and R2 = 0.970 at 180 min (RMSE = 0.900 and 0.593 mM, respectively), with no further improvement at 240 min otably, CV/EIS context proved essential for high accuracy at 180 min but contributed little at 120 min, revealing a shift from dynamics-driven early quantification to context-assisted later quantification. Thus, under controlled pure-culture conditions, the MES-based approach enables rapid acetate measurement within 120/180 min, with a clear trade-off between response time and accuracy.