1. Acid Mine Drainage

2. Microorganisms and Metal Toxicity microorganisms can modify toxicity of metals differing sensitivities of multicellular organisms and microorganisms to metals are basis of many antiseptic procedures

3. Soil as an Environment for Microorganisms dominated by inorganic geological material, which is modified by organisms to form soils typically not water saturated, so O 2 readily available can contain “mini” aquatic environments

4. Microorganisms in the Soil Environment peds – aggregated soil particles

5. Microbial populations in soils numbers can be very high –only small portion have been cultured microbes are constantly being added to soil –most do not survive make important contributions to biogeochemical cycling gram-positive bacteria are important members of soil communities

6. Deserts Soils desert crusts –microbial communities on soil surface cyanobacteria and associated commensals –help retain water from infrequent rainfalls –are fragile and easily damaged

7. Desert crusts or cryptogamic crusts Biological soil crusts are formed by living organisms and their by-products, creating a crust of soil particles bound together by organic materials Crusts are predominantly composed of cyanobacteria, algae, mosses, and lichens. Liverworts, fungi, and bacteria can also be important components