Screening of Biofilm Forming Bacteria from the Surfaces of Different Immersed Panels in the Process of Biofouling

Biofouling remains a persistent concern in aquatic environments, largely initiated by biofilm-forming bacteria that colonize submerged surfaces. The present study (2023) evaluates biofilm formation and bacterial diversity in the Vellar estuary, South east Coast of India. Aluminum, fiberglass, and wooden panels were immersed at a depth of one meter and the associated environmental parameters such as temperature (21.5–37.1 °C), salinity (13.3–35.5 ppt), pH (7.1–8.6), dissolved oxygen (3.12–5.16 mg L⁻¹) and rainfall (1.0–129.4 mm) were recorded monthly. Fifteen bacterial genera were isolated and identified based on morphological and biochemical characteristics, including Aeromonas sp, Bacillus sp, Pseudomonas sp, Vibrio sp, and Staphylococcus sp. Total viable bacterial density ranged from 2.9 × 10³ to 6.1 × 10³ CFU mL⁻¹, with the highest colonization on wooden panels (37.6%), followed by fiberglass (34.2%) and aluminum (28.1%). Pearson’s correlation analysis indicated strong positive associations between bacterial load and salinity (r = 0.77–0.79; P = 0.01), temperature (r = 0.47–0.57), and dissolved oxygen (r = 0.72–0.79), while rainfall and pH exhibited negative relationships. The findings highlight that both substrate type and seasonal variability driven by climatic factors significantly affect microbial colonization and biofilm development.