Sodium lactate-based enrichment method for isolation of microbial strains and evaluation of bioelectricity generation in bioelectrochemical systems.

Many environmentally relevant microorganisms remain uncultured or insufficiently characterized, limiting the discovery of strains with functional potential for bioelectrochemical applications. Although sodium acetate, glucose, and other carbon sources are commonly used for microbial enrichment, the use of sodium lactate as a defined single carbon source provides a selective strategy for enriching lactate-utilizing microorganisms with potential bioelectrochemical relevance. Therefore, this study developed a sodium lactate-based enrichment strategy for isolating microbial strains from environmental samples and evaluating their bioelectricity-generation potential in bioelectrochemical systems. Bacterial isolates were identified by 16S rRNA gene sequencing. The sediment-inoculated bioelectrochemical system achieved a peak current density of 14.77 μA cm-2, and 20 bacterial strains were isolated, whereas the organic fertilizer-inoculated BES produced 7.91 μA cm-2 and yielded seven isolates. Additionally, 5, 2, and 1 strains were isolated from soil, sediment, and wastewater, respectively. Among the tested strains, Aeromonas eucrenophila AS-26 and Paracidovorax citrulli AS-12 exhibited the highest current densities of 2.18 and 2.10 μA cm-2, respectively, with corresponding anode biofilm protein contents of 227.59 and 162.41 mg. These findings demonstrate that the sodium lactate-based enrichment method provides an effective approach for recovering environmental microorganisms with potential applications in bioelectrochemical systems.