How do environmentally friendly antifouling alkaloids affect marine fouling microbial communities?

Development of Antifouling Strategies for Marine Applications

Marine biofouling is an undeniable challenge for aquatic systems since it is responsible for several environmental and ecological problems and economic losses. Several strategies have been developed to mitigate fouling-related issues in marine environments, including developing marine coatings using nanotechnology and biomimetic models, and incorporating natural compounds, peptides, bacteriophages, or specific enzymes on surfaces. The advantages and limitations of these strategies are discussed in this review, and the development of novel surfaces and coatings is highlighted. The performance of these novel antibiofilm coatings is currently tested by in vitro experiments, which should try to mimic real conditions in the best way, and/or by in situ tests through the immersion of surfaces in marine environments. Both forms present their advantages and limitations, and these factors should be considered when the performance of a novel marine coating requires evaluation and validation. Despite all the advances and improvements against marine biofouling, progress toward an ideal operational strategy has been slow given the increasingly demanding regulatory requirements. Recent developments in self-polishing copolymers and fouling-release coatings have yielded promising results which set the basis for the development of more efficient and eco-friendly antifouling strategies.

Metabolomic Insights of Biosurfactant Activity from Bacillus niabensis against Planktonic Cells and Biofilm of Pseudomonas stutzeri Involved in Marine Biofouling

In marine environments, biofilm can cause negative impacts, including the biofouling process. In the search for new non-toxic formulations that inhibit biofilm, biosurfactants (BS) produced by the genus Bacillus have demonstrated considerable potential. To elucidate the changes that BS from B. niabensis promote in growth inhibition and biofilm formation, this research performed a nuclear magnetic resonance (NMR) metabolomic profile analysis to compare the metabolic differences between planktonic cells and biofilms of Pseudomonas stutzeri, a pioneer fouling bacteria. The multivariate analysis showed a clear separation between groups with a higher concentration of metabolites in the biofilm than in planktonic cells of P. stutzeri. When planktonic and biofilm stages were treated with BS, some differences were found among them. In planktonic cells, the addition of BS had a minor effect on growth inhibition, but at a metabolic level, NADP+, trehalose, acetone, glucose, and betaine were up-regulated in response to osmotic stress. When the biofilm was treated with the BS, a clear inhibition was observed and metabolites such as glucose, acetic acid, histidine, lactic acid, phenylalanine, uracil, and NADP+ were also up-regulated, while trehalose and histamine were down-regulated in response to the antibacterial effect of the BS.

Diversity and distribution of culturable fouling bacteria in typical mariculture zones in Daya Bay, South China

The diversity and distribution of culturable fouling bacteria in shellfish, fish and non-mariculture zones in Daya Bay were investigated by using a traditional culture-dependent approach combined with an analysis of bacterial 16S rRNA gene sequences. A total of 129 isolates of fouling bacteria belonging to 37 species in 25 genera were collected and identified, which indicated that the three different mariculture zones harbored abundant and diverse fouling bacterial community. At the genus level, Pseudomonas, Arcobacter and Curtobacterium dominated the fouling bacterial community. Moreover, approximately 46% of the 37 representative isolates could form biofilms. After comparing the diversity and distribution of the biofilm-forming bacteria in three different mariculture zones, it was concluded that the ratios of biofilm-forming bacteria in shellfish (68.4%) and fish (63.4%) in mariculture zones were much greater than those in non-mariculture (42.0%) zone. These results provide important information, for the first time, regarding the fouling bacterial community in typical mariculture zones in South China, which will establish a foundation to develop strategies for biofilm control and disease defense.