[P005] Poster

12:10 PM - 1:00 PM JST(3:10 AM - 4:00 AM UTC)

[P03-409] Optimizing cathodic algal–bacterial symbiosis in a microbial electrosynthesis system for enhanced carbon fixation and PHB production

○Bei-Jhen Hsu¹, Baala Anandapanmanaban¹, Shu-Hui Liu¹, Chung-Yen Yeh¹, Chi-Wen Lin¹ (1. National Yunlin University of Science and Technology (Taiwan))

Keywords:

microbial electrosynthesis system,algal–bacterial symbiosis,carbon fixation,polyhydroxybutyrate,response surface methodology,sustainable bioproduction

In response to the dual challenges of carbon neutrality and plastic pollution, developing bioelectrochemical systems capable of simultaneous CO2 utilization and bioplastic production has become increasingly important. In this study, a microbial electrosynthesis system (MES) integrating cathodic algal–bacterial symbiosis was developed to enhance carbon fixation and polyhydroxybutyrate (PHB) production. Response surface methodology (RSM) was applied to optimize key operating parameters, including the algal-to-bacterial ratio, temperature, pH, and influent CO2 concentration. System performance was evaluated in terms of electrochemical behavior, biomass accumulation, CO2 fixation, and PHB productivity. The MES achieved a maximum voltage output of 485 mV and a current density of 7.916 mA per cm2. The dry biomass concentrations of microalgae and bacteria reached 2.04 and 9.18 g per L, respectively, corresponding to an overall biomass productivity of 1.37 g per L per day. Meanwhile, the CO2 fixation rate and PHB productivity reached 0.246 g per L per day and 5.391 mg per L, respectively. RSM predicted the optimal operating conditions to be an algal-to-bacterial ratio of 1 to 8.32, a temperature of 25.5 degree C, a pH of 8.95, and an influent CO2 concentration of 27.89 percent. These results demonstrate that coupling MES with algal–bacterial symbiosis, together with statistical optimization, is an effective strategy for improving both carbon fixation and bioplastic production. This study highlights the potential of symbiotic bioelectrochemical systems for sustainable carbon conversion and the synthesis of value-added bioproducts.