Borrelia burgdorferi Complete genome

Characteristics Borrelia burgdorferi are spiral shaped microorganism (spirochetes) Gram-negative Motile On the average, seven periplasmic flagella are located at each cell end, and these flagella overlap at the central region of the cell. inhabit the gut of deer ticks ( Ixodes scapularis ). Named after American scientist Willy Burgdorfer who in 1982 isolated and determined the bacterium. Lymes disease is the most common tick-borne disease in the US.

Characteristics Chemo-organotropic derive energy by metabolizing organic molecules. Microaerophilic they require oxygen to survive, but only at low concentrations. Too much or lack of oxygen can be harmful to them. Catalase negative they are unable to break down hydrogen peroxide. They cannot synthesize their own amino acids, fatty acids, enzyme cofactors, and nucleotides.

Characteristics Optimal growth temperature is 34° to 37°C Generation time of 11 to 12 hours at 35°C. Their life cycle is directly linked to their host, and they depend on arthropod vectors (ticks) to infect mammals. They reside in infected mammals as well as in the gut of ticks. They multiply when there is enough blood ingested by the tick to support bacterial growth.

Genome structure DNA Molecule Summary 18 DNA molecules 28.5%G+C chromosomal bases 63.1% linear DNA bases Chromosomal Gene Summary 853 genes 793 protein coding genes 502 genes assigned a role, 51 genes not assigned a role 102 hypothetical genes

Cultivation The organism's small genome lacks the genes that are necessary for the synthesis of amino acids, fatty acids, enzyme cofactors, and nucleotides. In order for these spirochetes to be cultured, a very special type of medium is used called Barbour- Stoenner-Kelly (BSK) medium.

BSK =Barbour-Stoenner-Kelly Contains serum-supplemented mammalian tissue-culture that enables the bacterium to reproduce without ever having the need to synthesize too many biological compounds. Contains over thirteen ingredients in a rabbit serum base. Optimal temperature for growth =32-35 o C A microaerobic environment. Even under optimal conditions, the generation time is slow, about hours. BSK solidified with 1.3% agarose allows the production of colonies from single organisms.