Molybdenum reductase in Enterobacter cloacae

• Main Authors: Ariff, Arbakariya, Mohamad, Rosfarizan, Ghani, B., Sugio, Tsuyoshi, Abdul Karim, Mohamed Ismail
• Format: Article
• Language: English; English
• Published: Rapid Science Publishers 1997
• Online Access: http://psasir.upm.edu.my/id/eprint/51047/1/51047.pdf; http://psasir.upm.edu.my/id/eprint/51047/7/A_1018562719751.pdf; http://psasir.upm.edu.my/id/eprint/51047/; http://rd.springer.com/article/10.1023/A:1018562719751
• Institution: Universiti Putra Malaysia

Under anaerobic conditions in glucose–yeast extract medium with phosphate, Enterobacter cloacae strain 48 grew well and reduced Mo6+, to Mo5+. The activity of Mo6+-reductase was measured by the formation of molybdenum blue (complexation between Mo5+ and phosphate ion). Models based on logistic and Luedeking–Piret equations were found adequate to describe the growth of E. cloacae and Mo6+-reductase production. Mo6+-reductase production was found to be a growth-associated process. Washed intact cells, membrane fraction (after disruption using a sonicator) and fluid supernatant (after cell disruption) were able to reduce Mo6+. However, Mo6+-reductase activity was much lower in the supernatant fluid. The (NH4)2SO4-precipitated Mo6+-reductase extract from fluid supernatant was assayed for its properties. The optimum pH and temperature for Mo6+-reductase activity were 8 and 30°C, respectively. The apparent Michaelis–Menten constant (Km) and a maximum velocity (Vmax) were 16.5mm and 0.0192μmol/ml.h, respectively.