anaerobic Mn-mediated nitrification. Some bacterial communities, for e.g. photosynthetic mats,
which are diverse and highly structured, play a key-role in the recycling of mineral and biological components in diverse aquatic environments. In soft sediments, most of these microbial mats are formed of vertically stratified, multicolored and cohesive thin layers which are distributed along vertical micro-gradients of oxygen, sulfide and light. These
microbial communities which encompass, cyanobacteria, colorless sulfur bacteria, purple sulfur bacteria, and sulfatereducing bacteria, significantly contribute to carbon, nitrogen
and sulfur cycles and to sediment stability in some shallowwater habitats (Hubas et al., 2011).