Ingredient review
Crosslinked Bacillus Ferment
INCI: CROSSLINKED BACILLUS/GLUCOSE/SODIUM GLUTAMATE FERMENT
A gentle, biotech-derived film former that helps lock in moisture and improve skin feel, though research is still emerging.
In plain English
This ingredient is made by feeding glucose (a sugar) and sodium glutamate (a salt form of an amino acid) to Bacillus bacteria in a controlled lab setting. The bacteria ferment these nutrients into a polymer, which is then crosslinked — meaning the polymer chains are chemically linked together to form a more stable, flexible film. When applied to skin, this film helps reduce water loss, smooth the skin's surface, and give a soft, non-sticky feel. It's a modern alternative to traditional film formers like hyaluronic acid or silicones.
Review score
Safety, usefulness, and evidence
Potentially useful with some tradeoffs
The evidence base is still emerging, so marketing claims deserve extra caution.
Risk flags are low for most users, though the finished product can still irritate.
- Source
- biotech
- Evidence
- emerging
- Irritation
- low
- Clogging risk
- low
Quick decision guide
Useful, but context matters
Crosslinked Bacillus Ferment is generally a lower-concern ingredient when the full formula suits your skin.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Crosslinked Bacillus Ferment.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
lowLess likely to sting, burn, or bother most users, though sensitive skin can still react.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
emergingThe ingredient may be promising, but claims should be treated more cautiously.
What it is
A biotechnologically produced, crosslinked polymer derived from the fermentation of glucose and sodium glutamate by Bacillus bacteria. The crosslinking step creates a stable, flexible network that can form a thin film on the skin.
How it works
After application, the crosslinked polymer dries to form a flexible, breathable film on the skin's surface. This film acts as a physical barrier that slows transepidermal water loss (TEWL), helping the skin stay hydrated. It also smooths the skin's texture and can help other ingredients adhere better or last longer.
Pros
Gentle and non-irritating
Clinical and anecdotal reports indicate very low irritation potential, making it suitable for sensitive skin types.
Improves skin feel
Leaves a soft, smooth, non-sticky finish that can enhance the texture of serums and moisturizers.
Cons and cautions
Limited research
As a relatively new ingredient, there are fewer peer-reviewed studies on its long-term efficacy and safety compared to established humectants.
Not fully natural
While biotech-derived, the crosslinking step involves chemical modification, which may not appeal to those seeking completely natural or unprocessed ingredients.
Best for
- Anyone looking for a gentle, non-irritating film former to boost hydration
- People with normal to dry skin who want a smoother skin feel
Use caution if
- Those with known sensitivities to fermented ingredients or Bacillus-derived products (rare)
Usage tips
Safety summary
Current data suggests a low risk of irritation or sensitization. However, as with any new ingredient, patch testing is recommended for those with very sensitive skin or allergies to fermented products.
Research notes
Evidence is primarily from manufacturer studies and early clinical trials. Peer-reviewed research is limited, but existing data supports its role as a gentle film former and hydrator.
Common label clues
- Typical concentration
- 0.5% to 5%
- Regulatory status
- Generally recognized as safe for cosmetic use in the EU and US, though not specifically listed as a regulated substance. Always check local regulations.
- Common uses
- Serums, Moisturizers, Masks, Primers
- Environmental note
- Produced via controlled fermentation, which typically has a lower environmental footprint than petroleum-based film formers. However, the crosslinking step may involve chemical reagents that require careful disposal.
Good to know
- Crosslinking is a common technique used to improve the stability and performance of polymers in cosmetics.
- This ingredient is often used as a vegan-friendly alternative to animal-derived film formers like collagen.
Common questions
What is Crosslinked Bacillus Ferment in beauty products?
This ingredient is made by feeding glucose (a sugar) and sodium glutamate (a salt form of an amino acid) to Bacillus bacteria in a controlled lab setting. The bacteria ferment these nutrients into a polymer, which is then crosslinked — meaning the polymer chains are chemically linked together to form a more stable, flexible film. When applied to skin, this film helps reduce water loss, smooth the skin's surface, and give a soft, non-sticky feel. It's a modern alternative to traditional film formers like hyaluronic acid or silicones.
What does Crosslinked Bacillus Ferment do in a beauty product?
After application, the crosslinked polymer dries to form a flexible, breathable film on the skin's surface. This film acts as a physical barrier that slows transepidermal water loss (TEWL), helping the skin stay hydrated. It also smooths the skin's texture and can help other ingredients adhere better or last longer.
Is Crosslinked Bacillus Ferment safe for most people?
Current data suggests a low risk of irritation or sensitization. However, as with any new ingredient, patch testing is recommended for those with very sensitive skin or allergies to fermented products.
Who should be careful with Crosslinked Bacillus Ferment?
Those with known sensitivities to fermented ingredients or Bacillus-derived products (rare)
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.