Detailed explanation of the preparation method of bacterial cellulose

Bacterial Cellulose ( BC ) is a natural polymer material synthesized by specific bacteria . It has high purity, high crystallinity and excellent mechanical properties. It is widely used in the fields of medicine, food, electronic materials and functional membranes. This article will systematically introduce common preparation methods for bacterial cellulose from the aspects of bacterial selection, culture medium formula, preparation method and post-treatment process.

1. Commonly used strains and culture conditions

The production of bacterial cellulose mainly relies on high-yield strains such as Komagataeibacter xylinus .
Common culture conditions include:

Temperature: 28–30℃

pH : 5.0–6.0

Culture medium: Glucose, sucrose, fructose syrup, etc. are used as carbon sources, and corn slurry and yeast soaking powder are used as nitrogen sources
. These conditions provide bacteria with a good environment for synthesizing cellulose.

2. Main preparation methods of bacterial cellulose

1. Standal culture method

Stand culture is the most classic preparation method and is suitable for the preparation of laboratory and medical membrane materials.

Process characteristics: Add the inoculation solution to a shallow dish or triangular bottle, and let it stand for 5-10 days to form a cellulose film on the liquid level.

Advantages: High purity of the product and complete network structure.

Disadvantages: low output, large area, and difficult to scale.

2. Oscillation/smixing culture method

The bacteria can reproduce rapidly under oxygenated conditions by shaking or mechanical stirring.

Product form: granules or clustered cellulose.

Advantages: High volume productivity, suitable for amplification.

Disadvantages: Shear force may inhibit cellulose formation and the stirring conditions need to be optimized.

3. Tank fermentation method

Tank fermentation is the mainstream method of industrial production.

Key control: pH is maintained at 5.0–5.5 , dissolved oxygen remains above 30% , and a feeding strategy is adopted to avoid sugar inhibition.

Advantages: High production efficiency, suitable for large-scale continuous production.

Difficulty: The process is complex and requires precise control of dissolved oxygen and stirring.

3. Post-treatment process

The harvested bacterial cellulose needs to be processed through the following steps:

Alkaline wash : Commonly treated with 0.5–1.0 M NaOH at 80–95°C for 1–2 hours to remove cells and impurities.

Wash and neutralize by water : Rinse repeatedly until neutral, ensuring no residual alkali.

Drying method : You can choose natural air-drying, freeze-drying or supercritical CO₂ drying.

Modification treatment (optional): Improve mechanical properties and functionality through crosslinking or recombination.

4. Comparison of different preparation methods

method	Product form	Productivity	advantage	limitation
Stand-stand culture	Membrane cellulose	低	High quality and good purity	Difficult to scale
Shake /stir	Particles /clusters	中	Easy to enlarge, high flexibility	Shear force affects yield
Tank fermentation	Membrane /granules (adjustable)	高	Mainstream industry, high efficiency	Complex process

5. Summary

The preparation methods of bacterial cellulose mainly include three categories: standstill culture, oscillation / smixing culture and tank fermentation.

Laboratory research often uses standstill culture to obtain high-purity membrane-like materials;

Industrial production prefers tank fermentation, which can achieve high efficiency and scale;

The post-treatment and drying methods have an important impact on product performance.

With the continuous deepening of research on low-cost carbon sources and high-yield strains, the preparation process of bacterial cellulose will be more efficient and green in the future, and the application field will be further expanded.