Surendran Sankunny

Marine biofouling refers to the undesirable growth and adhesion of marine organisms such as barnacles, macro-algae, microbial slimes etc. on immersed structures. Tropical ocean environment teems with microorganisms, of which some adhere, both to the static ship hull and while en-route to the destination increasing roughness1. A laboratory-scale LIBS technique was used to analyse biofouling samples and its constituent common water-borne algae and bacterial species2. Biofouling composition was determined by collecting samples from marine structures and vessels and analysing them in laboratories. Biofouling characterization tests were also done such as SEM analysis. The Quanta 200 FEG Scanning Electron Microscope (SEM) was used for obtaining the SEM images. The structure of quartz crystal in the biofouling samples was also determined.

Marine biofouling refers to the undesirable growth and adhesion of marine organisms such as barnacles, macroalgae and microbial slimes on immersed structures. Biofouling composition is determined by collecting samples from marine structures and vessels and analyzing them in laboratories. Alternatively, an approach of online sensing based on Laser Induced Breakdown Spectroscopy (LIBS), which consists of analysis of the spectral emission from laser-induced plasma, can be considered for the elemental composition of biofouling. The study of marine biofouling using LIBS has not been attempted previously. In the present work, a laboratory-scale LIBS technique is used to analyze biofouling samples and its constituent common water-borne algae and bacterial species. First, LIBS database is created under controlled conditions for the selected biofilm constituent algae (Nitzschia sigma and Chaetoslorenzianus) and bacterial (Pseudomonas aeruginosa, Bacillus subtilis, E.coli) species. LIBS spectra are also acquired for Biofilm samples grown on Fiber Reinforced Plastic (FRP) and Stainless steel (SS) 316 L substrates suspended at a depth of 1 m in the tropical Indian Ocean. The studies are carried out for fouling growth period of 5, 10, 15 and 20 days in the intertidal region at a distance of 480 m from the shore. The study shows that the LIBS technique combined with the Principal Component Analysis (PCA) can be used for acquiring the spectra of biofouling species, its rapid classification and studying the growth characteristics. The LIBS database would serve as a means for early identification of marine fouling bacteria and algae species.

In the present study, LIBS spectra of biomolecules have been analyzed. The basic biomolecules considered for the analysis were Carbohydrates, Protein and Nucleic acids. It was possible to detect the characteristic emission lines of C, H, N, O, S etc. in the above biomolecules. The samples were prepared for laser ablation as biofilms on glass slides. Interference from substrate was observed in the LIBS spectra of samples. Raman spectra would also be acquired in future studies to obtain molecular information for the biomolecules.