Extraction And Performance Study Of Antifouling Compounds Produced By Marine Microorganism And Microalgae

In the marine industry, the accumulation of living organisms on artificial surfaces byadhesion, growth, and reproduction is known as marine biofouling. With the advances in moderntechnology, human development and utilization of the oceans has made significant progress, andbiofouling become thorny issues need to be resolved, therefore, the antifouling technologyhas obtained the widespread application. Antifouling coating is the most nature, economical andwidely used method among all the solutions proposed the history of navigation. The traditionalantifouling paints, including organic tin, cuprous oxide antifouling agents, cause serious pollutionof the marine environment. With the gobal ban of application of organotin-based marine coatingsby International Maritime Organization in2008, there is a practical and urgent need of identifyingenvironmentally friendly low-toxic and non-toxic antifouling compounds for marine industries.Marine natural products have been considered as one of the most promising cources of antifoulingcompounds in recent years. To meet various needs, a variety of effective and environmentallyfriendly AF compounds from natural sources have been developed and adopted in both researchand commercial laboratories. In this paper, the antifouling compounds were isolated and extractedfrom marine microalgae and the microorganism that screened from biofilm through chemicalmethods, and the antifouling activity was tested. The results showed that:（1）A fungus Aureobasidium pullulans HN and a bacteria Bacillus cereus, were isolated frommarine biofilm and identified. A bioassay-guided fractionation procedure was developed to isolateand purify antifouling compounds from A. pullulans HN and B. cereus. The procedure was:fermentation broth—aeration and addition of sodium thiosulfate—graduated pH and liquid-liquidextraction—SPE purification—GC-MS analysis. A toxicity test was conducted following eachstep. The antifouling active substances were extracted through inhibitive activity of thefermentation broth against Skeletonema costatum and barnacle larvae. The96h-EC50of thechloroform extract of A. pullulans HN against S. costatum was90.9μg·ml-1, and its24h-LC50 against B. ampHitrete larvae was22.2μg·ml-1; the96h-EC50value of the petroleum ether crudeextract of B. cereus against the test microalgae was391.5μg·ml-1, and the24h-LC50value againstthe test larvae was178.2μg·ml-1. After separation and purification, GC-MS was used for structuralelucidation of the compounds, the myristic, palmitic acids and octadecanoic acids were detected.Results also indicated that TIE was a highly useful tool for antifouling compound extraction.(2) Dinoflagellates are a major source of bioactive natural products compounds. In this studywe selected six marine dinoflagellates to investigate the antifouling potential of the bioactivecompounds. A preliminary examination was conducted to the crude extracts, the Amphidiniumcarterae that had the highest effect on anti-algal activity was conducted for further research. Then,the methanol crude extract was purified gradually to botain the organic extract B, the antifoulingactivity was elevated, and tested for antifouling activity, the EC50value against the test microalgaewas12.9μg·mL-1, and the LC50against B. amphitrete larvae was15.1μg·mL-1. Then, IR andUHR-TOF-MS were used to determine the type of the compounds, a series of unsaturated andsaturated fatty acids was detected. GC-MS was used for structural elucidation of the compounds,the palmitic, octadecanoic and eicosapentaenoic acids were detected. The data suggested that thefatty acids extracted from the microalgae A. carterae were with high antifouling activity, could beused as the source of the natural antifouling active substances.(3) Dunaliella salina has a wide range of applications in pharmaceuticals, cosmetics,nutritional supplements and aquaculture feeds, however, as we know, the potential application ofmetabolites produced by D. salina in antifouling has not been explored. In this study weperformed a series of operations to investigate the antifouling potential of the marine microalgaeD. salina. The test organisms used for antifouling evaluation were S. costatum and barnacle larvae.For the ethyl acetate crude extract, the antialgal activity were significant, the EC50value against S.costatum was58.9μg·ml-1. Then, the ethyl acetate crude extract was isolated gradually to botainthe organic extract B, the antifouling activity was elevated, and tested for antifouling activity, theEC50value against the test microalgae was21.2μg·mL-1, and the LC50against B. amphitretelarvae was18.8μg·mL-1. Then, IR、 UHR-TOF-MS and GC-MS were used for structuralelucidation of the compounds, a series of unsaturated and saturated16and18carbon fatty acidswere detected: palmitic acid;7,10-hexadecadienoic acid;4,7,10-hexadecatrienoic acid;4,7,10,13-hexadecatetraenoic acid; octadecanoic acid;9,12-octadecadienoic acid; linolenic acid. The data suggested that the fatty acids extracted from the microalgae D. salina were with highantifouling activity, could be used as substitutes for potent toxic antifouling compounds, resultingin a novel and environment friendly antifoulants in comparison with currently used biocides...