Process and industrialization key points for the preparation of bacterial cellulose (BC)

——From strains to finished products: process optimization, quality control and application implementation
(the technical parameters in the article are for reference for process amplification and research and development)

Bacterial Cellulose ( BC ) is directly synthesized by cellulose-producing bacteria (commonly Gluconacetobacter / Komagataeibacter and other genera) under specific nutrients and environments to directly synthesize an extremely pure nanofiber network. BC , with its high crystallinity, high specific surface area, excellent mechanical properties and biocompatibility, is becoming an important raw material for high value-added markets such as medical dressings, tissue scaffolds, functional composite materials and flexible electronics. Based on years of industrial research and development, Nanjing Tianlu Nanotechnology Co., Ltd. (hereinafter referred to as ' Tianlu ' ) has built a complete production system from strain screening, fermentation amplification to downstream modification and quality release, and can provide customers with customized BC materials and technical services.

1. Bacteria and culture media: determinants of productivity and fiber structure

Preferring high-yielding and stable strains is the starting point for high-quality BC . Commonly used culture media are Hestrin–Schramm ( HS ) formulas (to facilitate comparison and amplification with literature) - typical components include glucose ~20 g/L , tryptone ~5 g/L , yeast extract ~5 g/L , disodium phosphate and citric acid buffer, etc. The seed level is enlarged through a ladder: slope → oscillating liquid seed → fermenter inoculation to ensure that the bacteria enter the production tank in the logarithmic growth phase.

Key control parameters:

Temperature: 28–30°C (strain dependent)

Initial pH : 5.0–6.0 ( pH fluctuations during fermentation need to be monitored)

Dissolved oxygen: Static fermentation is used to synthesize membranes at the interface. The stirring / aeration system needs to optimize the balance of shear and dissolved oxygen to maintain morphology and crystallinity.

2. Fermentation mode: choosing from static to industrial mixing tanks

Static fermentation (interfacial membrane method): generates a dense and uniform sheet membrane with excellent crystallinity and mechanical properties, but limited volume production. It is suitable for research and development and high-end medical membrane preparation.

Stirred / air lift fermentation : Higher unit volume output (spherical or fibrous BC ) can be achieved through parameter optimization , but shear force needs to be reduced to avoid fiber breakage. Industrialization usually uses batch or semi-continuous feeding and controlled carbon source feeding rate ( fed-batch ) to balance productivity and quality.

During the pilot and scale-up processes, Tianlu adopted a multi-stage stirring strategy and low shear cycle to significantly increase the volume yield while maintaining the integrity of the nanofiber network.

3. Downstream purification and structure maintenance technology

The primary BC product contains bacterial cells and excess extracellular products, and needs to be desterilized, deproteinized and decolorized: Routinely use 1–5% NaOH to heat and boil with alkali to remove bacterial cells (temperature 80–90°C , time 0.5–2 h ), and then wash with deionized water until neutral. In order to maintain the three-dimensional network and pores to the maximum extent, the drying process needs to be applied selectively: freeze drying and supercritical drying can retain the porous structure, and hot air drying can be used for cost-prioritized large-scale products. Tianlu develops differentiated drying and molding processes for different downstream uses (medical dressings, composite materials, electronic insulation sheets), taking into account both cost and performance.

4. Functionalization and composite routes

In order to meet the application in multiple scenarios, bacterial cellulose BC is often chemically or physically modified: such as introducing carboxyl / amine groups to improve compatibility, cross-linking to enhance wet mechanics, or compounding with chitosan, collagen, and nanofillers to impart functions (antibacterial, conductive, and promote cell adhesion). Tianlu has batch experience in controlled grafting and surface plasma treatment, and can provide customized functions while maintaining the nanofiber network.

5. Quality control and characterization indicators (suggested release standards)

Standardized testing is the guarantee of industrial consistency. Key indicator recommendations include:

Purity (ash / organic residue)

Crystallinity ( XRD ) and crystal form analysis

Nanofiber diameter and network morphology ( SEM/TEM )

Chemical functional groups ( FTIR/XPS )

Thermal Stability ( TGA )

Mechanical properties (tensile strength, wet / dry modulus)

Moisture content, water absorption rate and microbial load (microbial limit)

Tianlu has established a that complies with medical and industrial standards QA/QC process , and provides complete test reports and batch traceability.

6. Key points of industrialization and sustainability considerations

Economics : Carbon source recovery, wastewater treatment and energy consumption optimization are the keys to reducing unit costs.

Safety and compliance : Medical-grade products must comply with relevant in vitro / in vivo safety evaluation and GMP requirements.

Environmental impact : Optimizing medium replacement components and waste liquid biological treatment can significantly reduce environmental burden.

Tianlu has achieved partial carbon source recovery and wastewater treatment up to standard in pilot scale-up, laying the foundation for long-term sustainable production.

Conclusion —Enterprise capabilities and cooperation methods

Nanjing Tianlu Nanotechnology Co., Ltd. combines microbial engineering, materials science and process amplification experience to provide one-stop solutions from strain customization, process pilot testing to large-scale production and downstream functionalization. Welcome to contact us to explore the industrialization path of bacterial cellulose in the fields of medical care, cosmetics, functional films and flexible electronics.