Phototrophic biofilms and their potential applications

Phototrophic biofilms occur on surfaces exposed to light in a range of terrestrial and aquatic environments. Oxygenic phototrophs like diatoms, green algae, and cyanobacteria are the major primary producers that generate energy and reduce carbon dioxide, providing the system with organic substrates and oxygen. Photosynthesis fuels processes and conversions in the total biofilm community, including the metabolism of heterotrophic organisms. A matrix of polymeric substances secreted by phototrophs and heterotrophs enhances the attachment of the biofilm community. This review discusses the actual and potential applications of phototrophic biofilms in wastewater treatment, bioremediation, fish-feed production, biohydrogen production, and soil improvement

COMPETITION BETWEEN ANOXYGENIC PHOTOTROPHIC BACTERIA AND COLORLESS SULFUR BACTERIA IN A MICROBIAL MAT

The populations of chemolithoautotrophic (colorless) sulfur bacteria and anoxygenic phototrophic bacteria were enumerated in a marine microbial mat. The highest population densities were found in the 0-5 mm layer of the mat: 2.0 X 10(9) cells CM-3 sediment, and 4.0 X 10(7) cells cm-3 sediment for the colorless sulfur bacteria and phototrophs, respectively. Kinetic parameters for thiosulfate-limited growth were assessed for Thiobacillus thioparus T5 and Thiocapsa roseopersicina Ml, both isolated from microbial mats. For Thiobacillus T5, growing at a constant oxygen concentration of 43-mu-mol l-1, mu(max) was 0.336 h-1 and K(s) 0.8-mu-mol l-1. Phototrophically grown Thiocapsa strain Ml displayed a mu(max) of 0.080 h-1 and a K(s) of 8-mu-mol 1-1 when anoxically grown under thiosulfate limitation. In a competition experiment with thiosulfate as electron donor, Thiocapsa became dominant during a 10-h oxic/14-h anoxic regimen at continuous illumination, despite the higher affinity for thiosulfate of Thiobacillus

COMPETITION BETWEEN ANOXYGENIC PHOTOTROPHIC BACTERIA AND COLORLESS SULFUR BACTERIA IN A MICROBIAL MAT

The populations of chemolithoautotrophic (colorless) sulfur bacteria and anoxygenic phototrophic bacteria were enumerated in a marine microbial mat. The highest population densities were found in the 0-5 mm layer of the mat: 2.0 X 10(9) cells CM-3 sediment, and 4.0 X 10(7) cells cm-3 sediment for the colorless sulfur bacteria and phototrophs, respectively. Kinetic parameters for thiosulfate-limited growth were assessed for Thiobacillus thioparus T5 and Thiocapsa roseopersicina Ml, both isolated from microbial mats. For Thiobacillus T5, growing at a constant oxygen concentration of 43-mu-mol l-1, mu(max) was 0.336 h-1 and K(s) 0.8-mu-mol l-1. Phototrophically grown Thiocapsa strain Ml displayed a mu(max) of 0.080 h-1 and a K(s) of 8-mu-mol 1-1 when anoxically grown under thiosulfate limitation. In a competition experiment with thiosulfate as electron donor, Thiocapsa became dominant during a 10-h oxic/14-h anoxic regimen at continuous illumination, despite the higher affinity for thiosulfate of Thiobacillus