Microalgae[Chlorella] role in the nitrogen cycle.

 

Microalgae are found in freshwater. Algae require an abundant amount of sunlight in the open air to grow and reproduce. All essential nutrient-containing media support microalgae growth. Microalgae consume and utilize nutrients in cellular metabolism. Chlorella is a well-known freshwater unicellular and free-living microalga, cells are 2 to10 µm in size. The cell wall of Chlorella contains membrane protein. These proteins are involved in different activities like preserving membrane potential and these activity control by Na⁺ and K⁺-ATPase pumps. Na⁺ and K⁺ -ATPase belongs to the P-type ATPase family. Osmoregulation, nutrient transport, Na⁺ concentration, and regulation of cell volume all materialize in the presence of the Na⁺ and K⁺ -ATPase pumps. Around 30% energy is required for the sodium-potassium movement in between cell membranes. Figure 1. Briefly explain the ion-pumping enzymes that contribute to the fluid balance and its electrolyte maintenance.

Figure 1 Pictorial represents Na⁺/ K⁺-ATPase cyclic reaction in the plasma membrane. 

Na⁺/ K⁺-ATPase activities arise in place of the plasma membrane (Figure 1). The Na⁺/K⁺ ATPase enzyme has a sodium and potassium bonding site for cations attachment. Conformational changes after attaching the Na⁺/K⁺. Conformational changes are important for the Na⁺/K⁺ influx and efflux. In the first step, the Na⁺/K⁺ ATPase enzyme binds 3 Na⁺ and ATP phosphorylated and 3 Na⁺ ions are released to the extracellular side (step 3).

Nitrification:

78% nitrogen is present in the environment, Atmospheric nitrogen involves the nitrification cycle at various steps (fig. 2). The reaction of nitrification is represented in Figure 2.

Nitrogen gas (N₂) is present in the atmosphere, and N₂ dissolves in seawater near the ocean's surface. Nitrogen gas is the most abundant of nitrogen in the water, yet it is toxic to most living things.

Atmospheric nitrogen cannot be used directly by microalgae, higher plants, and animals. Three major steps in nitrogen fixation processes.

·       N₂ fixation

·       Nitrification

·       Denitrification

Nitrification starts with N₂ fixation. Marine microalgae involve in nitrification, the atmospheric N₂ dissolves into seawater and is utilized by marine microbes according to the nitrogen cycle nitrogen requires for the development of microorganisms but it’s not beneficial for all living creatures. The High amount of nitrogen gives toxic effects on a living organisms.

Very few microorganisms are listed for N₂ consumption such as phytoplankton, cyanobacteria, Blue-green algae, and so on. In N₂ fixation, nitrogen converts into ammonium with the help of nitrogen-fixing microbes. Nitrogen converts into ammonium this process is known as "assimilation".

The next step is nitrification, ammonium is converted into anionic nitrogen compounds such as nitrates (NO₃^-, NO₂^-) this process is known as nitrification. These nitrates are uptake by microalgae. Dead microbes and animal excreta contain nitrogenous wastes.

Over time, these wastes decay and ammonia is released, ammonia again gets converted to nitrates in presence of nitrifying bacteria, and then nitrates denitrify to nitrogen gas and nitrates convert back to atmospheric nitrogen. Chlorella is a well-known microalga, Chlorella utilizes dissolves nitrogen in the form of the primary anion (NO₂^-) for glutamate synthesis and the secondary anion (NO₃^-) utilize in mRNA and production of nitrate reductase.

Figure 2 Schematic representation of microalgae involves the nitrogen cycle and removal of nitrates from the surrounding environment.