What is the Difference Between Proteobacteria and Nonproteobacteria

The main difference between proteobacteria and nonproteobacteria is that a few proteobatceria are photosynthetic whereas nonproteobacteria are photoautotrophs and chemoheteraotrophs.

Proteobacteria and nonproteobatceria are two types of bacteria with different characteristic features. Generally, proteobacteria are Gram-negative bacteria while nonproteobacteira are Gram-negative and Gram-positive bacteria.

Key Areas Covered

1. What are Proteobacteria
   • Definition, Characteristics, Importance
2. What is Nonproteobacteria
   • Definition, Characteristics, Importance
3. Similarities Between Proteobacteria and Nonproteobacteria
   • Outline of Common Features
4. Difference Between Proteobacteria and Nonproteobacteria
   • Comparison of Key Differences

Key Terms

Nonproteobacteria, Proteobacteria

What are Proteobacteria

Proteobacteria or Pseudomonadota are a diverse group of bacteria that are normally Gram-negative. The outer membrane of proteobacteria is composed of lipopolysaccharides. In general, many proteobacteria contain flagella and some are nonmotile and do not contain flagella. However, the most significant feature of proteobacteria is their metabolism. Usually, proteobacteria can be facultatively or obligately anaerobic, chemolithoautotrophic, and heterotrophic. A wide variety of pathogenic bacteria are in the group of proteobacteria such as Escherichia, Salmonella, Vibrio, Yersinia, Legionella, and many more. The nonparasitic, free-living proteobacteria are mainly responsible for nitrogen fixation.

Figure 1: E. coli

Initially, scientists classified purple bacteria and their relatives into a different taxonomic group: proteobacteria. The bacteria in this group show great diversity. Proteobacteria are a part of the microbiotic community in the lower reproductive tract of women. This group of bacteria is also associated with inflammation. In general, there are six classes of proteobacteria: they are Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Zetaproteobacteria, Hydrogenophilalia, and Acidithiobacillia.

What is Nonproteobacteria

Nonproteobacteria is another group of bacteria that can be either Gram-negative or Gram-positive. Metabolically, nonproteobacteria are either photoautotrophs or chemoheterotrophs. Cyanobacteria are photoautotrophic nonproteobacteria. In addition, chemoheterotrophic nonproteobacteria can be either motile or nonmotile. Generally, spirochetes are such motile nonproteobacteria that possess axial filaments. In contrast, cytophaga are the gliding nonproteobacteria. In addition, the nonmotile nonproteobacteria can be intracellular parasites such as Clamydia. Meanwhile, non-intracellular parasites of nonproteobacteria are either pointed rods such as Fusobacteria while non-pointed rods of nonproteobacteria are Bacteroides.

Figure 2: Spirochetes

Moreover, spirochetes are typically 250 μm long spiral-shaped bodies. As spirochetes are very thin, they are difficult to identify under a microscope. The axial filament of the spirochetes helps to propel and usually, spirochetes are highly motile. Gram-negative nonproteobacteria are Cytophaga, Fusobacterium, and Bacteroides. Cytophaga is an aquatic bacterium that is motile. Fusobacterium inhabits the mouth of humans. In general, most bacteroides are mutualistic and prevent the colonization of pathogens in the large intestine.

Similarities Between Proteobacteria and Nonproteobacteria

• Proteobacteria and nonproteobacteria are two types of bacteria with different characteristics.
• Bacteria are unicellular organisms with cell walls made up of peptidoglycans.
• Moreover, bacteria are prokaryotes that do not contain membrane-bound organelles.

Difference Between Proteobacteria and Nonproteobacteria

Definition

Proteobacteria refers to a domain of bacteria that includes medically and scientifically important species such as Escherichia, Salmonella, Vibrio, Helicobacter, and Yersinia while nonproteobaceria refer to a group of bacteria that contain photosynthetic bacteria.

Gram Stain

Proteobacteria are Gram-negative bacteria while nonproteobacteria are Gram-positive and Gram-negative bacteria.

Energy Metabolism

Proteobacteria are facultatively or obligately anaerobic, chemolithoautotrophic, and heterotrophic, while nonproteobatceria are photoautotrophs and chemohetarotrophs.

Conclusion

In brief, proteobacteria and nonproteobacteria are two types of wide groups of bacteria. Proteobacteria are Gram-negative bacteria while nonproteobacteria are either Gram-positive or Gram-negative. Proteobacteria are heterotrophs and very few are photosynthetic. In contrast, nonproteobatceria are photosynthetic and some are chemoheterotrophs. Therefore, the main difference between proteobacteria and nonproteobacteria is their mode of obtaining nutrition.

References:

1. “Pseudomonadota.” Wikipedia, Wikimedia Foundation, 24 Sept. 2022
2. “4.3: eria NonproteobactGram-Negative Bacteria and Phototrophic Bacteria.” Biology LibreTexts, Libretexts, 5 Mar. 2022.

Image Courtesy:

1. “Escherichia coli Gram Stain” By Dr Graham Beards – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “20100905 211652 Spirochetes ” By Bob Blaylock – Own Work (CC BY-SA 3.0) via Commons Wikimedia