Question

Why is iron so often a limiting nutrient, organisms overcome this problem? 40. when it seems to be so abundant in the environment, and how can

Answer 1

Iron is essential for almost all living organisms as it is involved in a wide variety of important metabolic process. However iron is not readily available to the organisms because it is not present in environment in soluble form, so iron is often a limiting nutrient. In early days of life on Earth due to emergence of photosynthesis, the atmosphere become oxidative and so iron prevailed in its trivalent form. The consequence was that most microorganism live today in a surrounding where the concentration of the soluble iron compounds is much too low to satisfy their physiological needs.

Microorganisms therefore employ various iron uptake systems to secure sufficient supplies from their surroundings. There is considerable variation in the range of iron Transporters and iron sources utilised by different microbial species. Pathogens in particular require efficient iron acqusition mechanisms to enable them to complete successfully for iron in the highly iron restricted environment of the host tissues and body fluids.

Many microorganisms cause this problem with the production of so-called siderophores, compounds which can form water soluble complexes with Fe^+3. They are released in situations of iron defieciency. Many siderophores has elaborate structures which can bind to the cell surface of the producing species.

Iron is often a trace element necessary for photosynthesis in plants. It is often defiecient in sea water because it is highly insoluble in seawater when in a variety of location it is the limiting nutrient for phytoplankton growth. Iron is also needed for nitrogen cycle. Microbial enzymes need iron to process phosphorus so it is important in the ocean.

Organism take iron from various sources with the help of various processes which enable them to utilise the insoluble form of iron.