Epulopiscium fishelsoni.pdf - Academic lab pages - School of ...

Epulopiscium fishelsoni

Introduction• Discovered in 1985, in the gut of surgeonfish• Belong to the low G-C Gram-positive bacteriaClostridium• Cigar-shaped and tan in colour

Characteristics• Very large : ~600um in length, Normal E. coli is~1um• 2000-million-folder larger in volume. Its cell wallcontains many folds in order to increase surface area• Can contain 200,000 copies of thegenome

Why so large, so many?• Deters predation• Extravagant collection of genomes may be a way for itto reap the benefits of size without cause starvation• Ramps up the rate at which Epulopiscium canproduce RNA and protein from its genes

ReproductionReproduces exclusively through an unusual form ofsporulation: 1-12 daughter cells are grown inside ofthe parent cell, until the cell eventually lyses andthe new bacteriaburst throughthe cell wall.

Symbiosis• Unable to culture it in vitro• Due to the daily cycle of the E. fishelsoni, it affectsthe pH of the surgeonfish's gut fluids differentlyduring the day and night, suggesting that cyclicmetabolic changes occur within the bacterium.• hp://microbewiki.kenyon.edu/index.php/Epulopiscium

Other interesting bugs• Buchnera aphidicola, the old recordkeeper in term of number of genomecopy• Thiomargarita namibiensis: the largestbacterium ~800um, found in 1999• A type of giant bacteria living in theeastern South Pacific was justdiscovered: can grow several cm long