Urease-negative uropathogen Kalamiella piersonii YU22 metabolizes urea by urea carboxylase and allophanate hydrolase enzyme system

Urea is one of the major components of the human urine and its breakdown by the uropathogens occurs mainly through the activity of the enzyme urease. However, a few reports suggest the presence of an alternate enzyme system for urea breakdown namely urea carboxylase (UC) and allophanate hydrolase (AH). We have previously reported the UC and AH system in the genome of a urease-negative uropathogen Kalamiella piersonii YU22 of the novel genus Kalamiella (reclassified recently as Pantoea).To validate the UC and AH activity in the presence of urea, we investigated the growth and urea utilization patterns of this bacterium. Growth kinetics, variations in media pH, NH4-N generation and UC and AH gene expressions were probed using urea-containing media. YU22 was able to grow in M9 media containing urea and increase the pH of the media due to the urea breakdown. Further, significantly higher concentrations of extracellular NH4-N (p