Query: NC_016930:11721 Rickettsia philipii str. 364D chromosome, complete genome
Lineage: Rickettsia philipii; Rickettsia; Rickettsiaceae; Rickettsiales; Proteobacteria; Bacteria
General Information: Rickettsiae are obligate intracellular Gram-negative bacteria mostly found in arthropods, some of which cause mild to severe diseases in humans. Spotted fever group rickettsiae (SFGR) cause disease in humans. R .philippi strain 364D, an SFGR, was isolated in 1966 from Dermacentor occidentalis ticks collected in Ventura county, California, and since then 364D has been detected in up to 11% of D. occidentalis from 8 California counties. It has now been recognized as causing eschar-associated illness.
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.