The document describes several species from the three domains of life - Archaea, Bacteria, and Eukarya. It discusses the unique characteristics and habitats of archaea such as Korarchaeum cryptofilum, methanogenic Methanococcus jannischii, and thermophilic Sulfolobus solfataricus. It also summarizes pathogenic bacteria including Salmonella enterica, Chlamydia trachomatis, Borrelia burgdorferi, and Actinomyces israelii. The smallest known photosynthetic organism, Prochlorococcus marinus, and antibiotic-producing Streptomyces griseus are also mentioned.