11: Mechanisms of Microbial Impacts

In the first two parts of this book, we consider properties of microorganisms and how environments influence their activities. For the final third of this book, we shift our perspective and consider how microorganisms impact their environments. These impacts are crucial for earth scientists to understand because microorganisms are collectively one of the most powerful forces shaping the planet, from the makeup of sediment being deposited in the oceans to the abundance of greenhouse gases in the atmosphere. Microorganisms make life possible in all higher trophic levels (Cavicchioli et al., 2019), and we cannot paint a complete picture of earth system processes if we leave them out. Moreover, we can combine our understanding of these impacts with our knowledge of the environmental controls on microbial populations to develop solutions for environmental challenges.

None of the major parts of the earth system are immune from microbial impacts. The chapters ahead (12–14) provide examples of impacts to the lithosphere, atmosphere, and hydrosphere. In this chapter, we focus on the coupled mechanisms by which impacts occur, which are divided into four categories: (1) catalyzing reactions, (2) generating biomass, (3) forming minerals, and (4) dissolving minerals.

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