Antifouling method and composition using chromen-4-one derivatives

#This application claims benefit from Chinese patent application number 200810087953.0, filed Mar. 20, 2008, the content of which is hereby incorporated in its entirety by reference.

#The present invention relates to antifouling methods and materials based on nontoxic bioactive agents. Particularly, it relates to an antifouling method and formulation based on one or more bioactive derivatives of chromen-4-one.

#Biofouling is the undesirable accumulation of micro-organisms, plants, and animals on artificial surfaces immersed in water such as ship hulls, docks, buoys, etc. More than 4000 organisms having been reported as being species causing biofouling, including bacteria, micro-algae, macro-algae, sea-grass, molluscs, crustacean, etc. Most fouling-causing organisms have a swimming larval stage followed by a sedentary adult stage that remains attached to its substratum throughout the remainder of its life. The attached adult organisms can increase frictional resistance on the hulls of ships, increase the weight of buoys, increase oil flat loading weight, block seawater pipes, decrease water exchange through aquaculture net boxes, and compete for space and food with cultured shellfish, among other negative effects.

#FIG. 1 is a flowchart of the bioassay-guided isolation of 4′,5,7-tryhydroxy-isoflavone (genistein) from the culture of Streptomyces fungicidicus.

#FIG. 2 shows the inhibitory effect of the compound 4′,5,7-tryhydroxy-isoflavone (genistein) on larval settlement of the barnacle Balanus amphitrite. The results are presented as the mean±standard deviation of at least three replicates (n=3).

#FIG. 3 shows hydrolysis of genistein in buffer solutions, artificial seawater and natural seawater. The concentrations were determined by HPLC before hydrolysis (open bar), after 4 days (gray bar), and 7 days (black bar) of incubation at 50° C. in dark for hydrolysis. Tested solutions included artificial seawater (ASW), filtered natural seawater (FSW), and 20 mM acetic buffers of pH 5, 7, and 9. The concentration of genistein was presented as the mean±standard deviation of three replicates (n=3).

#A. The Strains Producing Antifouling Compounds

#The strain of Streptomyces fungicidicus was isolated from sediment samples from 5000 m depth in west Pacific Ocean (N10o50′35″; W154o05′28″). The samples were kept at 0° C. and 44° C. before and after arriving laboratory, respectively.

#The strain of S. fungicidicus was isolated by the following enrichment techniques. Sediment samples (about 1 g) were suspended in 10 ml artificial seawater. After mixing, 200 μl of the suspension was spread on 2216E agar plate and incubated at 10° C. Colonies with different shape or color were transferred to a new agar plate for new incubation and further isolation. The final identification was conducted by detection of 16S rRNA sequence (SEQ ID No: 1). 16S rRNA sequence was amplified by the primers 8F (5′-AGAGTTTGATCCTGGCTCAG-3′) and 1525R (5′-AGAGTTTGATC CTGGCTCA-3′). Sequencing reactions were performed by using forward primers 26F (5′-AGAGTTTGATC CTGGCTCA-3′) and 355F (5′-A CTCCTACGGGAGGCAGC-3′) and reverse primers 1492R (5′-GGYTACCTTGTTACGAC TT-3′) and 1525R (5′-AAGGAG GTGWTCCARCC-3′), SEQ ID Nos: 2-7, respectively. The sequence was deposited in Genbank under accession NO. AY636155.