“Microbes – The Good, The Bad, and the Globally Powerful”

Important Groups of Microbes 1. Bacteria 2. Fungi 3. Protozoa Eukaryotes (“true nucleus”) Fungi -- single cells (e.g., yeasts); mycelia (e.g., mushrooms) Plants (algae) Animals (e.g., protozoans, rotifers, nematodes) Prokaryotes (“before the nucleus”) Bacteria – Eubacteria (true bacteria) – E. coli, Cyanobacteria – Archaebacteria (old bacteria) – deep oceans, hot springs

Important Groups of Microbes 1. Bacteria * Found everywhere * Resting stages * Short generation times * Locomotion

Soils – bacteria = 10 9 per mL (fungi = m per mL) Water (ocean, lakes, streams) – bacteria = 10 6 per mL (no fungi) Elemental composition of bacteria = Element% of dry weight C55 O20 N10 H8 P3 S1

Bacteria on the head of a pin (~5 μm long)

Cholera - intestine thin section

Campylobacter - (food poisoning) rotary 6,000 rpm

Proteus - 20 μm

Microbial “mat” on the surface of a salt marsh – an ecological community

Evolution of Bacteria 1. Two Main Groups = Eubacteria and Archaebacteria 2. Evolutionary Distance: Eubacteria Archaebacteria Plants Animals (a) Eubact -- Archae Plant Animal ? - OR - ? (b) Eubact Archae Plant Animal

Important Groups of Microbes 2.Fungi * Thin strands called “hyphae” * Uncommon in aquatic environments * Common in terrestrial environments * Secrete enzymes to break down cellulose

* Fungal hyphae (~15 µm). A network of hyphae = a mycelium. * Picture of “fairy ring” of mushrooms. Ring moves outward as easily digestible organic matter is used up. * One mycelium covered 1290 acres and was thousands of years old (100s of tons). Soils - fungi = m/mL Water = no fungi

Gall on tree – fungal infection

Bread mold Hyphae strands & sporangia

Fungus fruiting bodies

Root fungus “mycorrhizae”

Important Groups of Microbes 3.Protozoa * Single-celled eukaryotes * Important predators on bacteria

Protozoan ciliate. Their primary food is bacteria and very small algae.

1.Assimilative versus Dissimilative Processes All cells need ATP and a source of Carbon 2.How do Microbes make a Living? “Production” versus “Respiration”

Respiration requires a reduced organic compound as an electron donor and an oxidized molecule as an electron acceptor (Freeman 2002). Taken together, this is a “Reduction-Oxidation” or “Redox” reaction.

Cyanobacteria (blue green algae) and “heterocysts” where the nitrogen fixation occurs. Oxygen poisons N-fixation.

Legume roots with nodules that enclose the N-fixing bacteria PeaClover

Root fungus – “endotrophic”

Summary Be able to answer these questions: What is the diversity of microbes? How do the different kinds of microbes function in gaining energy? What impacts do microbes have on ecosystems and our globe? Take-home points: 1. Microbes can do anything they want, wherever they want, and 2. Without microbes, humans wouldn't be alive.