Development of microbial biofilms and the recruitment of propagules on the surfaces of man-made structures in the marine environment cause serious problems for the navies and for marine industries around the world. Current antifouling technology is based on the application of toxic substances that can be harmful to the natural environment. For this reason and the global ban of tributyl tin (TBT), there is a need for the development of “environmentally-friendly” antifoulants. Marine microbes are promising potential sources of non-toxic or less-toxic antifouling compounds as they can produce substances that inhibit not only the attachment and/or growth of microorganisms but also the settlement of invertebrate larvae and macroalgal spores. However, so far only few antilarval settlement compounds have been isolated and identified from bacteria. In this review knowledge about antifouling compounds produced by marine bacteria and diatoms are summarised and evaluated and future research directions are highlighted.

Bacterial quorum sensing (QS) is a cell–cell communication and gene regulatory mechanism that allows bacteria to coordinate swarming, biofilm formation, stress resistance, and production of toxins and secondary metabolites in response to threshold concentrations of QS signals that accumulate within a diffusion-limited environment. This review focuses on the role of QS signaling and QS inhibition in marine bacteria by compounds derived from marine organisms. Since the formation of a biofilm is considered to be an initial step in the development of fouling, direct and indirect effects of QS signals and inhibitors on the process of marine biofouling are discussed. Directions for future investigations and QS-related biotechnological applications are highlighted.

Any natural or artificial substratum exposed to seawater is quickly fouled by marine microorganisms and later by macrofouling species. Microfouling organisms on the surface of a substratum form heterogenic biofilms, which are composed of multiple species of heterotrophic bacteria, cyanobacteria, diatoms, protozoa and fungi. Biofilms on artificial structures create serious problems for industries worldwide, with effects including an increase in drag force and metal corrosion as well as a reduction in heat transfer efficiency. Additionally, microorganisms produce chemical compounds that may induce or inhibit settlement and growth of other fouling organisms. Since the last review by the first author on inhibition of biofouling by marine microbes in 2006, significant progress has been made in the field. Several antimicrobial, antialgal and antilarval compounds have been isolated from heterotrophic marine bacteria, cyanobacteria and fungi. Some of these compounds have multiple bioactivities. Microorganisms are able to disrupt biofilms by inhibition of bacterial signalling and production of enzymes that degrade bacterial signals and polymers. Epibiotic microorganisms associated with marine algae and invertebrates have a high antifouling (AF) potential, which can be used to solve biofouling problems in industry. However, more information about the production of AF compounds by marine microorganisms in situ and their mechanisms of action needs to be obtained. This review focuses on the AF activity of marine heterotrophic bacteria, cyanobacteria and fungi and covers publications from 2006 up to the end of 2012.