Lecture 3

Soil Microorganisms• Soil microorganisms include bacteria, actinomycetes,fungi, algae,and protozoa.• Viruses, which only grow in other living cells, are molecules of RNAor DNA within protein coats and are discussed here because theyplay an important part in the microbiology of soils.• Viruses require a viable metabolizing host organism in order toreproduce or duplicate. They induce the host organism tomanufacture the necessary components for virus reproduction.Many viruses can cause diseases such as those found in plants(e.g., tobacco mosaic and potato leaf roll) and animals (e.g., footand-mouthdisease and bovine leukemia).• Survival of viruses that are pathogenic to humans and animals, andwhich are known to be in municipal wastewaters and biosolids,animal manures, and lagoons, as well as household septic wastes,is a potential concern when these materials are used in a landapplication program.