Discovery, Yield Improvement, and Application in Marine Coatings of Potent Antifouling Compounds Albofungins Targeting Multiple Fouling Organisms

Abstract

Marine biofouling caused huge economic losses of maritime industries. We aim to develop high-efficient, less-toxic, and cost-effective antifoulants to solve the problems of biofouling. In this study, we described the antifouling compounds albofungin and its derivatives (albofungin A, chrestoxanthone A, and chloroalbofungin) isolated from the metabolites of bacterium Streptomyces chrestomyceticus BCC 24770, the construction of high-yield strains for albofungin production, and application of albofungin-based antifouling coatings. Results showed that these albofungins have potent antibiofilm activities against Gram-positive and Gram-negative bacteria and anti-macrofouling activities against larval settlement of major fouling organisms with low cytotoxicity. With the best antifouling activity and highest yield in bacterial culture, albofungin was subsequently incorporated with hydrolyzable and degradable copolymer to form antifouling coatings, which altered biofilm structures and prevented the settlement of macrofouling organisms in marine environments. Our results suggested that albofungins were promising antifouling compounds with potential application in marine environments.

Mode of action of antimicrobial agents albofungins in eradicating penicillin- and cephalosporin-resistant Vibrio parahaemolyticus biofilm

“…As a polycyclic isoquinolone-xanthone compound first isolated from Actinomyces in the 1970s ( 15 , 16 ) and later discovered in different Streptomyces species ( 17 ), albofungin shows a wide range of potent bioactivities, including antitumor, antifungal, and anti-HIV activity ( 17 – 19 ). More importantly, albofungin exhibits predominant antibacterial and antibiofilm properties according to our previous studies, which can be utilized to reduce biofouling in marine environments ( 18 , 20 ). For example, albofungin was capable of inhibiting the formation of biofilms in multiple strains of marine bacteria and “ESKAPE pathogens,” including Staphylococcus aureus , Sulfitobacter pontiacus , Escherichia coli , and Acinetobacter baumannii with low cytotoxicity ( 18 , 20 ).…”

“…More importantly, albofungin exhibits predominant antibacterial and antibiofilm properties according to our previous studies, which can be utilized to reduce biofouling in marine environments ( 18 , 20 ). For example, albofungin was capable of inhibiting the formation of biofilms in multiple strains of marine bacteria and “ESKAPE pathogens,” including Staphylococcus aureus , Sulfitobacter pontiacus , Escherichia coli , and Acinetobacter baumannii with low cytotoxicity ( 18 , 20 ). Furthermore, albofungin binds to the transglycosylase domain of penicillin-binding proteins in cell wall biosynthesis ( 21 ).…”

“…Albofungin exhibited broad-spectrum antibacterial and antibiofilm activities against Gram-negative and Gram-positive bacteria ( 18 , 20 ). It can be used as a coating agent in marine environments because of its significant antifouling activity and low cytotoxicity ( 20 ). The present study is the first to elucidate the possible underlying mode of action of albofungin against Gram-negative bacteria.…”

“…The overnight culture of V. parahaemolyticus cells was diluted into around 10 7 CFU mL –1 in LB medium added with 0.5% of glucose. The biofilm inhibition assay was measured through the MTT assay ( 20 ). The absorbance was determined using the CLARIOstar Plus microplate reader under 570 nm.…”

Mode of action of antifouling compound albofungin in inhibiting barnacle larval settlement

“…We previously isolated a series of albofungin derivatives from Streptomyces chrestomyceticus BCC 24770, and all the derivatives showed a broad spectrum of antibiofilm activities against both Gram-positive and Gram-negative bacteria. 10 Albofungin also exhibited potent antilarval settlement activity against two major fouling organisms, the barnacle A. amphitrite and the bryozoan B. neritina in both lab and field tests and its antilarval settlement performance was comparable with butenolide, 10 indicating that albofungin is a promising antifouling reagent in maritime applications.…”