Comparative transcriptomics analysis of the G20 biofilms grown on copper and polycarbonate surfaces.

Sulfate-reducing bacterial (SRB) biofilms are prevalent across diverse environments, playing key roles in biogeochemical sulfur cycling while also contributing to industrial challenges such as biofouling and biocorrosion. Understanding the genetic and physiological adaptations of SRB biofilms to different surfaces is crucial for developing mitigation strategies. This study presents a comparative transcriptomic analysis of G20 biofilms grown on copper and polycarbonate surfaces, aimed at elucidating their differential responses at the molecular level. RNA sequencing revealed 1255 differentially expressed genes, with copper-grown biofilms exhibiting upregulation of Dde_1570 (flagellin; log2FC 2.31) and Dde_0831 (polysaccharide chain length determinant; log2FC 1.15), highlighting enhanced motility and extracellular polymeric substance production. Conversely, downregulated genes on copper included Dde_0132 (Cu/Zn efflux transporter; log2FC -3.37) and Dde_0369 (methyl-accepting chemotaxis protein; log2FC -1.19), indicating a metabolic shift and stress adaptation to metal exposure. Morphological analysis via SEM revealed denser biofilm clusters with precipitates on copper, whereas biofilms on polycarbonate were more dispersed. AFM analysis showed a 4.6-fold increase in roughness on copper (44.3 ± 3.1 to 205.89 ± 8.7 nm) and a 3.8-fold increase on polycarbonate (521.12 ± 15.2 to 1975.64 ± 52.6 nm), indicating surface erosion and structural modifications. Protein-protein interaction analysis identified tightly regulated clusters associated with ribosomal synthesis, folate metabolism, and quorum sensing, underscoring their role in biofilm resilience. Additionally, functional annotations of uncharacterized genes revealed potential biofilm regulators, such as Dde_4025 (cytochrome-like protein; log2FC 4.18) and Dde_3288 (DMT superfamily permease; log2FC 3.55). These findings provide mechanistic insights into surface-dependent biofilm formation, with implications for designing antifouling materials and controlling microbial-induced corrosion.