Microbes Diversity - Variety of sizes, shapes, environments. Adaptability - Hot springs, thermal vents, salt lakes, ocean depths, the Arctic. Synthetic capabilities. Beneficial - O2 production: N2 fixing, sulfur/carbon/nitrogen cycles. Absolute requirement for life as we know it. Food production. <5% pathogenic. Inner Space - vs. outer space, i.e. like ocean exploration. Personal - Oral cavity - 100,000,000/ml. sliva; 50/50 aerobes/anaerobes. GI Tract - Anaerobes and E.coli Skin Surface - Staphylococus, Propionibactor