Microbial biosphere

Abstract

Evolution of prokaryotic biosphere is considered from the system point of view. It starts with the appearance of first organisms, the ∼3.5 Ga date makes a border between the observed and imagined biosphere. Prokaryotic community dominated from Archaean to Mesoproterozoic. Prokaryotes make a sustainable community due to the cooperative action of specialized forms. The main route for establishing community is made by trophic links. Structure of the trophic links in prokaryotic community making a trophic network is an invariant, with secondary adaptive deviations. Material balance is the ultimate requirement for a long living self-supporting system. The system of biogeospheric cycles is dictated by the constancy of biomass composition establishing quantitative ratio between Corg:Norg:P org. Biospheric processes are driven by the Corg-cycle. Carbon assimilation is limited by the illuminated moist surface populated by producers, and this means that the Corg-production remains within an order of magnitude of 102 Gt/yr. Evolution of the prime producers makes a stem for evolution of the biospheric-geospheric system but cyanobacteria integrated as chloroplasts remain to be its driving force. Decomposition of organic compounds is performed by organotrophic destructors, anaerobic being less effective. Destructors determine the residual Corg accumulation. Recalcitrant Corg remaining in the sedimentary record is equilibrated by O2 and other oxidized compounds such as Fe-oxides or sulfates. The geospheric and biotic interactions include both direct and biotically mediated processes; the most important is the weathering- sedimentation pathway. The prokaryotic community makes a sustainable frame into which all other more complex forms of life fit in. That makes the prokaryotic biosphere a permanent essence of the whole system. New actors might come in and substitute for functional components only when they fit to the existing system. Evolution of the large system is additive rather than substitutive. All originated from cyano-bacterial community - is the slogan. © Springer 2008.