Effect of combined nitrogen on the expression of nitrate reductase and nitrite reductase in Azorhizobium caulinodans
Raju, K.S.; Sharma, N.D.; Lodha, M.L.
Indian Journal of Experimental Biology 35(8): 866-870
1997
ISSN/ISBN: 0019-5189 PMID: 9475063 Document Number: 473712
In aerobically grown Azorhizobium caulinodans strain IRBG 46, in vivo expression of nitrate reductase (NR) and nitrite reductase (NiR) requires the presence of either nitrate or nitrite. On the contrary mere microaerobic conditions are sufficient for the expression of NR and NiR, however, addition of nitrate to the growth medium enhanced the activities of the enzymes. Optimum concentration of nitrate for maximum expression of NR and NiR activities was different in aerobic and microaerobic conditions. Nitrite was released into the medium both in aerobic and microaerobic conditions beyond a particular concentration of nitrate in the medium. Dissimilatory nitrate reduction was affected to a lesser extent by ammonium compared to assimilatory nitrate reduction.