Isolation and characterization of Enterobacter cloacae capable of metabolizing asparagine.
A gram-negative, rod-shaped bacterium capable of utilizing L-asparagine as its sole source of carbon and nitrogen was isolated from soil and identified as Enterobacter cloacae. An intracellularly expressed L-asparaginase was detected and it deaminated L-asparagine to aspartic acid and ammonia. High-pressure liquid chromatography analysis of a cell-free asparaginase reaction mixture indicated that 2.8 mM L-asparagine was hydrolyzed to 2.2 and 2.8 mM aspartic acid and ammonia, respectively, within 20 min of incubation. High asparaginase activity was found in cells cultured on L-fructose, D-galactose, saccharose, or maltose, and in cells cultured on L-asparagine as the sole nitrogen source. The pH and temperature optimum of L-asparaginase was 8.5 and 37-42 degrees C, respectively. The half-life of the enzyme at 30 degrees C and 37 degrees C was 10 and 8 h, respectively.
Nawaz
M S
MS
Division of Microbiology, National Center for Toxicological Research, Jefferson, AR 72079, USA. mnawaz@nctr.fda.gov
Zhang
D
D
Khan
A A
AA
Cerniglia
C E
CE
D001215:Asparaginase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001216:Asparagine / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002851:Chromatography, High Pressure Liquid; D003470:Culture Media; D016972:Enterobacter cloacae / Q000201:enzymology* / Q000254:growth & development / Q000302:isolation & purification*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000378:metabolism; D012988:Soil Microbiology; D013696:Temperature
D003470:Culture Media; D001216:Asparagine; D001215:Asparaginase; D009584:Nitrogen