Phototrophic biofilm

In addition to these natural roles, phototrophic biofilms have also been adapted for applications such as crop production and protection, bioremediation, and wastewater treatment.

The chemoheterotrophs use the photosynthetic waste products from the phototrophs as their carbon and nitrogen sources, and in turn perform nutrient regeneration for the community.

[1][2] Various groups of organisms are located in distinct layers based on availability of light, the presence of oxygen, and redox gradients produced by the species.

[1] Eukaryotic algae and cyanobacteria in the outer portion use light energy to reduce carbon dioxide, providing organic substrates and oxygen.

[2] Communication between the microorganisms is facilitated by quorum sensing or signal transduction pathways, which are accomplished through the secretion of molecules which diffuse through the biofilm.

[1] Phototrophic biofilms and microbial mats have been described in extreme environments like thermal springs,[3] hyper saline ponds,[4] desert soil crusts, and in lake ice covers in Antarctica.

The 3.4-billion-year fossil record of benthic phototrophic communities, such as microbial mats and stromatolites, indicates that these associations represent the Earth's oldest known ecosystems.

Biofilms in terrestrial systems can contribute to improving soil, reducing erosion, promoting growth of vegetation, and revitalizing desert-like land, but they can also accelerate the degradation of solid structures like buildings and monuments.

[1] There is a growing interest in the application of phototrophic biofilms, for instance in wastewater treatment in constructed wetlands, bioremediation, agriculture, and biohydrogen production.

[1] Promoting growth of phototrophic biofilms in agricultural settings improves the quality of the soil and water retention, reduces salinity, and protects against erosion.

Biofilm growth can also degrade other pollutants by oxidizing oils, pesticides, and herbicides and reducing heavy metals like copper, lead, and zinc.

[2] Heavy metal detoxification in wastewater treatment can also be achieved with these microbes primarily through passive mechanisms such as ion exchange, chelation, adsorption, and diffusion, which constitute biosorption.