Compare and contrast the pseudomonads, Azotobacter, and the acetic acid bacteria in terms of O 2 requirements, electron donors, pathogenicity, and habitats. The enteric bacteria are a large group of facultative aerobic rods of great medical and molecular biological significance. Vibrio and Photobacterium species are marine, and many species are bioluminescent. Describe two major properties of Proteus species that distinguish them from other enteric bacteria. The Rickettsias are obligate intracellular parasites, many of which cause disease.
Rickettsias are deficient in many metabolic functions, and obtain key metabolites from their hosts.
Name a disease caused by a Rickettsia species. Section 13.13 Spirilla are spiral-shaped chemoorganotrophic prokaryotes widespread in the aquatic environment. The genera Helicobacter and Campylobacter are pathogenic spirilla. Spirilla are distributed among the alpha, beta, gamma, delta, and epsilon subdivisions Proteobacteria. 13.15 Sheathed bacteria are filamentous Proteobacteria in which individual cells form chain within an outer layer called the sheath.