Unmasking photogranulation in decreasing glacial albedo and net
autotrophic wastewater treatment
Abstract
In both natural and built environments, microbes on occasions manifest
in spherical aggregates instead of solid-affixed biofilms. These
microbial aggregates are conventionally referred to as granules.
Cryoconites are mineral rich granules that appear on glacier surfaces
and are linked with expanding surface darkening, thus decreasing albedo,
and enhanced melt. The oxygenic photogranules (OPGs) are organic rich
granules that grow in wastewater with photosynthetic aeration and
present potential for net autotrophic wastewater treatment in a compact
system. Despite obvious differences inherent in the two, cryoconite and
OPG pose striking resemblance. In both, the order Oscillatoriales in
Cyanobacteria envelope inner materials and develop dense spheroidal
aggregates. We explore the mechanism of photogranulation on account of
high similarity between cryoconites and OPGs. We contend that there is
no universal external cause for photogranulation. However, cryoconites
and OPGs, as well as their intra variations, which are all are under
different stress fields, are the outcome of universal physiological
processes of the Oscillatoriales interfacing goldilocks interactions of
stresses, which select for their manifestation as granules. Finding the
rules of photogranulation may enhance engineering of glacier and
wastewater systems to manipulate their ecosystem impacts.