Metabolism and Genomics of Nitrite-Oxidizing Bacteria: Emphasis on Studies of Pure Cultures and of Nitrobacter Species

Abstract

This chapter attempts to place the physiology and biochemistry of nitrite-oxidizing bacteria (NOB) into context with information derived from the annotated Nitrobacter genomes. Daims et al. provide an excellent review of insights gained into the physiology and ecology of Nitrospira that were obtained primarily by using genomics tools and other cultivation-independent methods. The genome of N. hamburgensis is the largest of the Nitrobacter genomes and appears to have maintained a greater level of metabolic flexibility and adaptability than the other sequenced representative. The genes on the largest plasmid, pPB13, appear to be biased toward carbon/energy metabolism. A discussion of the current status of knowledge about carboxysomes is presented in this chapter. The chapter talks about genomic evidence for a potentially different mechanism of CO2 fixation by ''Candidatus Nitrospira defluvii'' presented by Daims et al. The glyoxylate pathway genes were annotated, and several genes encoding for enzymes that facilitate metabolism of pyruvate, acetate, and glycerol were identified. The genome analysis of Nitrobacter has provided some new and confirmatory insights into the biology of this genus.