The key difference between Nitrosomonas and Nitrobacter is that Nitrosomonas is a bacterium that converts ammonium ions or ammonia into nitrites while Nitrobacter is a bacterium that converts nitrite into nitrates in the soil.
The nitrogen cycle is an important biogeochemical cycle. Nitrogen cycle occurs via four major processes: nitrogen fixation, ammonification, nitrification and denitrification. Soil microorganisms participate in most chemical reactions in the nitrogen cycle and convert atmospheric nitrogen into usable forms. Nitrification is the biological transformation of ammonia or ammonium ions into nitrates by oxidation. It is an integral part of the nitrogen cycle. It is facilitated by two types of chemoautotrophic bacteria known as Nitrosomonas and Nitrobacter. They work under aerobic conditions. Nitrification is initiated by Nitrosomonas. Nitrosomonas converts ammonia and ammonium ions into nitrite. Then, Nitrobacter converts nitrite into nitrate.
CONTENTS
1. Overview and Key Difference
2. What is Nitrosomonas
3. What is Nitrobacter
4. Similarities Between Nitrosomonas and Nitrobacter
5. Side by Side Comparison – Nitrosomonas vs Nitrobacter in Tabular Form
6. Summary
What is Nitrosomonas?
Nitrosomonas is a genus of nitrifying bacteria. Nitrosomonas species are Gram-negative and rod-shaped. They are chemoautotrophic bacteria which convert ammonium ions and ammonia into nitrite ions in the soil. Therefore, Nitrosomonas plays a vital role in the nitrogen cycle.
Figure 01: Nitrosomonas spp.
Nitrosomonas species work under aerobic conditions and optimum pH of 7.5 to 8.5. Moreover, Nitrosomonas spp has polar flagella; hence, they are motile bacteria. They belong to a group of beta proteobacteria.
What is Nitrobacter?
Nitrobacter is a genus of gram-negative nitrifying bacteria. Nitrobacter species convert nitrite in the soil into nitrates. This is an important step of the nitrogen cycle. Moreover, it is a crucial step in plant nutrition. Nitrate is the accessible form of nitrogen of plants.
Figure 02: Nitrobacter spp.
Nitrobacter depends on Nitrosomonas for its nitrogen source. Therefore, both Nitrosomonas and Nitrobacter are extremely important bacteria for plant nutrition. Nitrobacter species have sub-terminal flagella. Hence, they are motile bacteria. Moreover, Nitrobacter belongs to the alpha subclass of proteobacteria.
What are the Similarities Between Nitrosomonas and Nitrobacter?
- Nitrosomonas and Nitrobacter are two chemoautotrophic bacteria found in soil and water.
- They participate in oxidizing ammonia into nitrate.
- Therefore, they are nitrifying bacteria.
- They work best at the optimum pH between 7.5 and 8.5.
- Nitrobacterpopulation is strongly dependent on the population of Nitrosomonas.
- Both bacteria are sensitive to a number of environmental conditions such as pH, dissolved oxygen concentration, temperature, and inhibitory chemicals, etc.
- Both bacteria are rod-shaped.
- Moreover, they are Gram-negative bacteria.
- Both use CO2 as their carbon source.
- They reproduce by binary fission.
What is the Difference Between Nitrosomonas and Nitrobacter?
The key difference between Nitrosomonas and Nitrobacter is that Nitrosomonas participates in the first step of nitrification, which is the conversion of ammonia into nitrites, while Nitrobacter participates in the second step of nitrification, which is the conversion of nitrite into nitrates. Nitrosomonas belongs to the group of beta proteobateria while Nitrobacter belongs to the group of alpha proteobacteria. So, this is another difference between Nitrosomonas and Nitrobacter.
Below infographic summarizes the differences between Nitrosomonas and Nitrobacter in tabular form for side by side comparison.
Summary – Nitrosomonas vs Nitrobacter
Nitrification is the conversion of ammonium ions or ammonia into nitrate ions in the soil. It is a two-step process. First, Nitrosomonas converts ammonium ions into nitrite. Then, Nitrobacter converts nitrite ions into nitrate ions. This is a crucial step in plant nutrition since nitrate (NO3–) is the plant accessible form of nitrogen. Nitrosomonas belongs to the beta subclass of proteobacteria while Nitrobacter belongs to the alpha subclass of proteobacteria. Thus, this is the summary of the difference between Nitrosomonas and Nitrobacter.
Reference:
1. “Nitrosomonas.” Wikipedia, Wikimedia Foundation, 1 Jan. 2021, Available here.
2. “Nitrobacter.” ScienceDirect Topics, Available here.
Image Courtesy:
1. “Nm-eutropha” By Asw-hamburg – Own work (CC BY 3.0) via Commons Wikimedia
2. “TEM Image of Nitrobacter winogradskyi str. Nb-255” By Professor William Hickey – (CC BY-SA 2.0) via Commons Wikimedia