1. Bacteria: Examples include Rhizobium, Azotobacter, and Pseudomonas. 2. Fungi: Examples include Mycorrhizae, Trichoderma, and Penicillium. 3. Protozoa: Examples include Amoeba, Paramecium, and Euglena. 4. Algae: Examples include Chlorella, Spirogyra, and Diatoms. 5. Actinomycetes: Examples include Streptomyces and Actinomyces. 6. Nematodes: Examples include C. elegans and Root-knot nematodes.