Bacterial Cellulose ( BC ) ** is a high-purity β-1,4- glucose chain polymer synthesized by Gram-negative aerobic bacteria (mainly Komagataeibacter xylinus ) under specific culture conditions . Its three-dimensional nanofiber network structure, ultra-high crystallinity ( >80% ) and good biocompatibility make it have wide application potential in cutting-edge technologies such as biomedicine, flexible electronics and bionic materials.

Among all kinds of synthesis paths, static culture method has become the preferred experimental preparation method in current research and high-end applications due to its advantages in control of BC structural integrity and uniformity.

1. Static culture method mechanism and conditional control

The static culture method is based on the formation of an aerobic metabolic reaction microenvironment at the air --liquid interface of BC strains , which prompts them to synthesize cellulose microfiber filaments (diameter 20–100 nm ) and self-assemble into continuous films.

Key culture parameters:

parameter	Typical range	Technical Key Points
Culture temperature	28–30°C	Approximate the optimal enzyme activity area, promoting efficient catalysis of extracellular glucan synthase complex
Initial pH	5.0–6.0	Avoid the accumulation of by-product acids in carbon source metabolism, resulting in decreased yield
Carbon source concentration	20–50 g/L	Glucose, glycerin or waste molasses are commonly used options, which directly affects the synthesis rate.
Oxygen supply	Static gas -liquid interface diffusion	Oxygen is a key speed limit factor, and the design of the culture container must avoid excessive pressure on the liquid surface.
Cultivation cycle	7-14 days (film thickness 0.5~3mm)	Can control film thickness and crystallinity, suitable for different uses

2. Microstructure and performance analysis of BC membrane

The prepared by static culture method BC membrane showed high uniformity and good controllability in morphology and structure:

Typical characterization data (using SEM/TEM, XRD, TGA, FTIR, etc.):

Performance metrics	Static BC membrane data	Application Relevance
Nanofiber diameter	20–60 nm	Influence mechanical enhancement and cell adhesion ability
Specific surface area	80–120 m²/g	Determine adsorption and composite properties
Crystallization degree	≥ 80% (XRD analysis)	Determines mechanical strength and thermal stability
Decomposition temperature	280–320°C (TGA analysis)	Can be used in high temperature coatings or electronic packaging
Water content	≥ 90% (in situ wet)	Suitable for hydrogels, biostents and other scenarios

3. Process advantages and applicable directions of static cultivation method

Dimension	Description of the advantages of static cultivation
Controllable structure	The film has regular morphology and uniform thickness, making it easy to standardize film-level products
Minimum impurities	No lignin and hemicellulose, only NaOH boils + water washing after treatment
Low cost moderate	Simple primary production equipment, no large-scale stirring and fermentation system required
High adaptability	It can adapt to different scenarios through morphology regulation, such as tissue engineering membranes, battery separators, and coated substrates.

4. Technical bottlenecks and future directions

Current Challenge:

Limited yield : static systems have low output per unit volume and are susceptible to oxygen transfer efficiency;

The cost of carbon sources is relatively high : industrialization still relies on high-purity sugar sources, and agricultural by-product replacement needs to be explored;

Long culture cycle : Compared with stirring and fermentation, the production cycle is about 2 to 3 times longer;

Innovation Trends:

Technical path	describe
Synthetic Biological Strain Engineering	Using gene regulation pathways to improve glucan synthase expression and enhance yield
Multi-layer modular static system development	Build a large-scale cultivation platform for automatic temperature control and layered membrane extraction
Functional BC membrane development	Grafting carboxyl, amino, and conductive materials to achieve intelligent response and high conductivity

V. Conclusion

The static culture method has irreplaceable scientific and engineering value in basic research on bacterial cellulose, membrane-level product development and functional material exploration. In the future, through the integration of microbial engineering and materials science, prepared by static method BC will gradually achieve a leap from ' laboratory materials ' to ' industrial platform materials ' and serve a wider range of green manufacturing and high-end applications.