Query: NC_007799:727798 Ehrlichia chaffeensis str. Arkansas, complete genome
Lineage: Ehrlichia chaffeensis; Ehrlichia; Anaplasmataceae; Rickettsiales; Proteobacteria; Bacteria
General Information: This strain is the first isolate of Ehrlichia chaffeensis, which was obtained from a patient on an army base in Arkansas, USA in 1990. Causes disease in humans. This organism is an obligate intracellular pathogen that exists within vacuoles in the cytoplasm of monocytes or granulocytes. Transferred during an insect (tick) bite, it can cause disease in humans (human monocytic ehrlichiosis) and can reside in several other animals and is a problem in immunocompromised patients. The bacterium inhibits phagosome-lysozome fusion as well as programmed cell death (apoptosis) of the host cell, similar to what is observed with Anaplasma phagocytophilum.
Subject: NC_005126:4824500 Photorhabdus luminescens subsp. laumondii TTO1, complete genome
Lineage: Photorhabdus luminescens; Photorhabdus; Enterobacteriaceae; Enterobacteriales; Proteobacteria; Bacteria
General Information: This strain was isolated on Trinidad and Tobago. It is a symbiont of the nematode Heterorhabditis bacteriophora. Bioluminescent bacterium. This organism is unusual in that it is symbiotic within one insect, and pathogenic in another, the only organism that is known to exhibit this dual phenotype. Enzymes are then released by the bacteria that result in rapid degradation of the insect body, allowing both bacteria and nematode to feed and reproduce. During this period Photorhabdus luminescens releases bacteriocidal products, including antibiotics and bacteriocins, that prevent infection of the larva by competitive microbes. The result is promotion of Photorhabdus luminescens-nematode interactions that result in continuation of the symbiotic relationship. In order to engage in a symbiotic relationship with the nematode and a pathogenic one with the insect larva, the bacterium encodes specific factors that encourage both. These include a large number of genes that code for secreted toxins and enzymes, as well as genes that encode products for the production of antibiotics and bacteriocins. Secretion of these products occurs by an array of systems including type I, type II, and type III secretion systems. The type III system is closely related to the Yersinia plasmid-encoded type III system. Genes that promote symbiotic relationships are also encoded on genomic islands on the chromosome including some that affect nematode development. Virulence genes appear to be active during exponential growth. Symbiotic genes appear to function during stationary phase (post-exponential) growth. The switch from one state to another is controlled. Photorhabdus luminescens is capable of giving off light, a complex process that requires the products of the lux operon.