Transcriptome of K. stuttgartiensis mbr1, and organism grown in a mixed culture bioreactor.. kuenenia stuttgartiensis mbr1

Anaerobic ammonium-oxidizing (anammox) bacteria are of global, industrialand cell biological significance. They contribute up to 50% to the nitrogen removal from the ocean, are used in wastewater treatment for the removal of ammonium and do not conform to the typical prokaryotic cell plan. Anammox bacteria combine ammonium with nitrite and produce dinitrogen gas via the intermediates nitric oxide and hydrazine (anammox reaction) while nitrate is formed as a by-product. The Gram-negative anammox cell contains a specialized, membrane-bound compartment called the anammoxosome where this anammox reaction takes place. The anammox substratesammonium, nitrite and by-product nitrate have to cross the outer-, cytoplasmic- andanammoxosome membranes to enter or exit the anammoxosome. The genomes of all anammox species harbour multiple copies of ammonium-, nitrite- and nitrate transporter genes. The reason for the high redundancy in nutrient transporters anammox bacteria is unknown. We hypothesized, and our results show, that distinct transporter proteins are expressed under different growth conditions, i.e. the availability of the substrates ammonium and nitrite. These results give a first insight in the potential role of the multiple nutrient transporters in regulating transport of substrates and products in and out of the compartmentalized anammox cell.