Physiological resilience and bioelectrogenic potential of a distinct Shewanella lineage from the Southern Blue Amazon

The genus Shewanella is renowned for its metabolic versatility and role in extracellular electron transfer (EET). This study characterizes Shewanella sp. (REG000848), a lineage isolated from the South Atlantic Blue Amazon. Phylogenomic metrics (ANI < 85% and dDDH < 27%) reveal that REG000848 is a genetically divergent lineage, exhibiting unique adaptations to marine stressors. The strain demonstrated exceptional physiological resilience, maintaining growth at temperatures up to 45°C, salinity levels of 12% NaCl, and a pH range of 4.5-10.0, significantly exceeding the thresholds of the model S. oneidensis MR-1. Genomic analysis identified a robust Mtr respiratory machinery, with multiple paralogs of the MtrB/PioB family and deca-heme cytochromes (MtrC and OmcA), providing the framework for its bioelectrogenic potential. Pangenomic analysis defining REG000848 as a specialized ecotype within the Southern Blue Amazon. In Microbial Fuel Cells (MFCs), the lineage achieved an immediate Open-Circuit Voltage (OCV) of 250 mV, suggesting a biofilm-independent electron transfer mechanism. These findings underscore the South Atlantic as a strategic reservoir of genetic resources, positioning Shewanella sp. (REG000848) as a promising bio-platform for sustainable energy and industrial biotechnology in processes that are usually stressful for most microorganisms.