Study GuideMicrobiology–Soil Microbiology1.Other Biogeochemical CyclesSoil is not only important for thenitrogen cycle—it is also the main setting for several otherbiogeochemical cycles. These cycles move essential elements through living organisms, the soil,water, and the atmosphere. Some of the most important ones involvephosphorus, sulfur, carbon,and oxygen.1.1The Phosphorus CyclePhosphorus is essential for life. Living organisms use phosphorus to make:•Nucleotides(the building blocks of DNA and RNA)•Phospholipids(key parts of cell membranes)•Phosphorylated proteinsPhosphorus enters soil and water mainly asphosphate ions. These come from sources such as:•Decaying plants and crops•Leaf litter•Garbage and organic wasteRole of MicroorganismsIn the soil, microorganisms interact with phosphorus compounds like:•Calcium phosphate•Magnesium phosphate•Iron phosphateMicrobes break phosphorus free from these compounds and absorb it as thephosphate ion (PO₄³⁻).This phosphate is then used to build DNA, RNA, phospholipids, and other vital molecules.When microorganisms are eaten by larger organisms, phosphorus moves up thefood chain,becoming more concentrated at higher levels.Preview Mode
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