English abstract
Marine biofouling - an undesirable growth of micro- and macro-organisms on man-made surfaces - causes enormous problems in the maintenance of ships, boats, fishing nets, cages and desalination plants worldwide. This study aimed to investigate antifouling effect of Omani traditional paint and a copper based commercial paint. Cotton fibers, polyethylene fibers and wooden panels treated with the paints and control (untreated) were deployed at Im depth in the marina of Bandar Rawdha for six weeks. Every week substrates were collected and microbial biofouling were assessed using 4,6-diamino-2 phenylindol DAPI counting, measurement of chlorophyll a concentration, and determination of dominant diatoms, dinoflagellate and cyanobacterial species using microscopy. Inhibition of bacterial growth and biofilm formation by the paints were screened using bacterial isolates from fibers and panels. The densities of bacteria increased on all tested materials except cotton fibers coated with the copper based paint. The copper based and Omani traditional paints significantly prevented bacterial fouling on cotton fibers only. The lowest chlorophyll a concentrations were found on cotton and synthetic fibers treated with the copper based paint. The type of the substrate determined presence or absence of particular species of diatoms, dinoflagellates and cyanobacteria. Eighteen different bacterial strains belonging to the genera Psychrobacter, Pseudomonas, Enterobacter, Stenotrophomonas, Halomonas, Lysinibacillus, Schewanella, Vibrio, Acinetobacter and Pseudoalteromonas were isolated. All isolates were positive in catalase tests and negative in cellulose hydrolysis and indole production. Two isolates were positive in gelatin hydrolysis and three isolates were positive in starch hydrolysis. Growth of most isolates was inhibited by the Omani traditional paint and antibiotic control (streptomycin) but not by the copper based paint. Only antibiotic control effectively suppressed biofilm formation of the isolates. This study suggested that antifouling performance depends both on the type of substrate and the type of antifouling paint. This study recommended that for the prevention of growth of bacteria on cotton fibers, the copper based paint and the Omani traditional paint should be used.
