Eco-friendly bacterial prodigiosin-based antibiofouling coating for marine structure applications

Abstract

Marine biofouling, the unwanted accumulation of living organisms on manmade structures is worsening and creating an adverse economic impact. In this study, a more sustainable antibiofouling paint was formulated by using natural antibiofouling agent. Prodigiosin, a bacterial pigment extracted from Serratia marcescens was used as the antibiofouling agent and pigment. The antibiofouling properties of crude prodigiosin were studied by assessing the antibacterial properties, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and toxicity assay. The performance of antibiofouling paint at different pigment composition incorporated with crude prodigiosin was studied in laboratory and in natural seawater. Based on the result obtained, the antibacterial test demonstrated the largest inhibition zone against B. subtilis (4.0 ± 0.3 cm) at 10000 ppm and the smallest inhibition zone against E. coli (2.0 ± 0.4 cm) at 1000 ppm. The MIC values ranged from 390 to 3126 ppm and MBC values ranged from 1562 ppm to 6250 ppm for all bacteria tested. Crude prodigiosin showed a low toxicity value (LC50 = 4270.203 ppm). The comparative study of binder showed that vinyl ester resin performed better in comparison to epoxy resin in all tests, namely antibacterial test (B. subtilis: 3.77 ± 0.1 cm, E. coli: 3.43 ± 0.1, P. aeruginosa: 3.63 ± 0.3, S. aureus: 4.00 ± 0.1), surface roughness and adhesion test (Class 5B). Steel plate painted with crude prodigiosin was able to retain its cleanliness at high flowrate areas (significant, p = 0.05) in natural seawater while a thinner mud settlement was observed at low flowrate areas (not significant, p = 0.05). Based on the research outcomes, it was observed that with thorough study, prodigiosin has a high potential as an effective environmental friendly antibiofouling agent since it can inhibit the attachment of marine organisms on wetted surfaces.