A Complete Scientific Explanation

Gellan gum is widely used in food, beverages, plant tissue culture, pharmaceuticals, and biotechnology. Yet one question comes up again and again—especially from technically minded customers and researchers:

What kind of bacteria is in gellan gum?
Or more accurately: What bacteria produces gellan gum?

This article provides a clear, scientifically accurate, and easy-to-understand explanation of the bacterial origin of gellan gum, how it is produced, and why the final product is completely safe and bacteria-free.



Understanding Gellan Gum at a Molecular Level

Gellan gum is a high-molecular-weight polysaccharide. It does not occur naturally in plants or seaweed like agar or carrageenan. Instead, it is produced through microbial fermentation, a process commonly used to manufacture food ingredients such as xanthan gum, citric acid, and many amino acids.

Importantly:

Gellan gum itself is not a bacterium and does not contain bacteria.
It is a purified biopolymer produced by bacteria.

The Bacterium That Produces Gellan Gum

🦠 Scientific Name: Sphingomonas elodea

Gellan gum is produced by the bacterium:

Sphingomonas elodea

Key characteristics of this microorganism:

  • Gram-negative
  • Aerobic
  • Non-pathogenic
  • Naturally occurring in the environment
  • Safe for industrial fermentation

When gellan gum was first discovered, this bacterium was classified as Pseudomonas elodea. Later taxonomic studies reassigned it to the genus Sphingomonas, which is now the accepted scientific classification.

Why Sphingomonas elodea Produces Gellan Gum

During fermentation, Sphingomonas elodea secretes gellan gum as an exopolysaccharide—a protective carbohydrate layer released outside the bacterial cell.

From a biological perspective, this polysaccharide helps the bacterium:

  • Protect itself from environmental stress
  • Retain moisture
  • Form stable extracellular structures

From an industrial perspective, this same polymer happens to have excellent gelling, stabilizing, and suspending properties.

Industrial Fermentation Process (Simplified)

To avoid confusion, it's helpful to understand how gellan gum is actually manufactured:

Step 1: Controlled Fermentation

The bacterium is grown in sterile fermentation tanks containing sugars, minerals, and nutrients.

Step 2: Gellan Gum Secretion

As the bacteria metabolize the sugars, they secrete gellan gum into the liquid medium.

Step 3: Bacterial Removal

After fermentation is complete, all bacterial cells are removed through filtration and purification.

Step 4: Purification and Drying

The gellan gum is purified, washed, dried, and milled into a fine powder.

✅ Final Result

A pure polysaccharide powder with:

  • No live bacteria
  • No microbial activity
  • No genetic material

Does Gellan Gum Contain Bacteria?

No.
This is one of the most common misconceptions.

By the time gellan gum reaches the customer:

  • The producing bacteria are completely removed
  • The product is microbiologically clean
  • It meets food, pharmaceutical, and laboratory safety standards

This is why gellan gum is approved for use in:

  • Food products
  • Infant nutrition
  • Plant tissue culture
  • Pharmaceutical formulations

Why Gellan Gum Is Preferred Over Agar in Microbiology

Because of its microbial origin and controlled structure, gellan gum offers several advantages over agar, especially in laboratory and plant tissue culture applications:

  • Higher gel clarity
  • Stronger gels at lower concentrations
  • More consistent gel strength
  • Better thermal stability control
  • Reduced batch-to-batch variation

These properties are directly linked to its bacterial fermentation origin, which allows precise molecular control.

High Acyl vs Low Acyl Gellan Gum (Brief Context)

The same bacterium produces gellan gum, but post-fermentation processing determines whether the product is:

  • High acyl gellan gum – soft, elastic, thermoreversible gels
  • Low acyl gellan gum – firm, brittle, thermo-irreversible gels

This distinction is important for food texture design, plant tissue culture media, and pharmaceutical gels—but the producing bacterium remains the same.

Safety and Regulatory Perspective

Because Sphingomonas elodea is non-pathogenic and the final product is purified, gellan gum is recognized globally as safe when produced under proper manufacturing standards.

It is accepted by:

  • Food authorities
  • Pharmaceutical regulators
  • Research institutions worldwide

Final Clarification (Key Takeaway)

Let's summarize clearly:

  • Gellan gum is not bacteria
  • Gellan gum does not contain bacteria
  • It is produced by the bacterium Sphingomonas elodea
  • The final product is a purified polysaccharide

This bacterial fermentation origin is exactly what gives gellan gum its unique, reliable, and highly controllable functional properties.