Escherichia coli MG1655 induces the nitrogen-regulated(Ntr) response when grown in a medium in which ammonia is absent and nitrogen is supplied by an alternate source. We investigated the response to low levels of ammonia using DNA microarray analysis. Our results revealed an increase in expression of genes that coordinate the Ntr response, implying that the Ntr response is activated when E. coli senses diminishing levels of ammonia not simply nitrogen starvation. Early activation of the Ntr response may allow E. coli to maintain basal level metabolism by scavenging for nitrogen-containing compounds.
Title
Microarray analysis of the Ntr response in Escherichia coli in response to diminishing ammonia levels
Palmer, A. K. and L. F. Caslake. (2009) "Microarray analysis of the Ntr response in Escherichia coli in response to diminishing ammonia levels." Journal of the Pennsylvania Academy of Science 83(2/3): 82–86.