MOLYBDENUM AS A MICRONUTRIENT FOR NITROBACTER.

Area of Science:

• Microbiology
• Biochemistry
• Environmental Science

Background:

• Nitrobacter are autotrophic bacteria crucial for the nitrogen cycle.
• Micronutrient requirements for Nitrobacter are not fully understood.
• Molybdenum's role in microbial metabolism is significant.

Purpose of the Study:

• To investigate the requirement of Nitrobacter for molybdenum.
• To determine the optimal concentration of molybdenum for Nitrobacter growth.
• To assess molybdenum's impact on nitrite utilization and cell mass.

Main Methods:

• Utilized chemically purified media and prior bacterial growth for depletion.
• Measured nitrite utilization and cell mass development over 5 days.
• Conducted short-term studies with varying molybdenum concentrations.

Main Results:

• Molybdenum addition increased nitrite utilization and cell mass by approximately 11-fold.
• Maximal response observed at molybdenum concentrations as low as 10(-9)M.
• Estimated 2,000 molybdenum atoms per Nitrobacter cell; no other metal substituted.

Conclusions:

• Molybdenum is an essential micronutrient for Nitrobacter.
• Molybdenum does not directly influence thermodynamic efficiency but is vital for growth.
• A method for obtaining large Nitrobacter cell masses was developed.