Bacterial synthesis method: Detailed explanation of green and efficient nanocellulose preparation technology

Bacterial synthesis method: Detailed explanation of green and efficient nanocellulose preparation technology

Nanocellulose ( NC) is an emerging nanomaterial, attracting much attention due to its excellent performance and wide application prospects. Traditional nanocellulose preparation methods, such as mechanical methods and chemical methods, have problems such as high energy consumption and high pollution. As a green and environmentally friendly and mild preparation method, bacterial synthesis has developed rapidly in recent years. This article will focus on the process flow of nanocellulose preparation by bacterial synthesis, and elaborate on the key control points of each step in detail.

1. Process flow for preparing nanocellulose by bacterial synthesis

The preparation of nanocellulose by bacterial synthesis mainly includes the following steps:

Sperm selection and culture

Strain selection : Commonly used strains include Gluconacetobacter xylinus, rhizobacterium, etc. Among them, Acetobacterium leukococcus is the most commonly used species, with strong ability to synthesize bacterial cellulose and high yield.

Media preparation : Media is the basis for bacterial growth and synthesis of cellulose, and its composition and ratio directly affect the yield and quality of bacterial cellulose. Commonly used culture medium ingredients include carbon sources (such as glucose, fructose, etc.), nitrogen sources (such as peptone, yeast extract, etc.), inorganic salts (such as dipotassium hydrogen phosphate, magnesium sulfate, etc.).

Culture condition control : Bacterial growth and metabolism require appropriate environmental conditions, including temperature, pH, dissolved oxygen, etc. Generally speaking, the optimal growth temperature of Acetobacterium leucorrhea is 28-30℃, and the optimal pH is 5.0-6.0, and sufficient oxygen supply is required.

Generation of bacterial cellulose membranes

Static culture : The inoculated culture medium is placed under static conditions and the bacteria will form a gel-like bacterial cellulose membrane on the surface of the culture medium. Static culture is simple to operate, but the yield is low.

Dynamic culture : In order to increase the yield of bacterial cellulose, dynamic culture methods can be adopted, such as shaker culture, fermenter culture, etc. Dynamic culture can increase the contact area between the culture medium and the air, increase the amount of dissolved oxygen, and promote bacterial growth and metabolism.

Extraction and purification of bacterial cellulose membranes

Cleaning : Remove the bacterial cellulose membrane from the culture medium and wash repeatedly with deionized water to remove residual medium components.

Alkaline treatment : Soak the washed bacterial cellulose membrane in sodium hydroxide solution to remove residual bacterial and proteins and other impurities.

Bleaching : Soak the alkali-treated bacterial cellulose membrane in sodium hypochlorite solution to remove pigments and improve the purity of bacterial cellulose.

Preparation of nanocellulose

Mechanical dispersion : The purified bacterial cellulose membrane is mechanically dispersed, such as high-speed stirring, high-pressure homogenization, etc., to obtain a nanocellulose suspension.

Ultrasonic treatment : The mechanically dispersed nanocellulose suspension is sonicated to further disperse the nanocellulose and improve its dispersion stability.

2. Key control points

Strain selection : Selecting strains with strong synthesis ability and high yield is the key to improving bacterial cellulose production.

Media ingredients : Optimize the media ingredients and ratio to provide sufficient nutrients for bacterial growth and metabolism.

Culture conditions : Strictly control the temperature, pH value, dissolved oxygen and other culture conditions to create an environment suitable for bacterial growth and metabolism.

Extraction and purification : Use appropriate extraction and purification methods to remove impurities and improve the purity of bacterial cellulose.

Nanocellulose preparation : Select appropriate mechanical dispersion and sonication conditions to obtain uniformly sized, stable dispersion of nanocellulose suspension.

3. Summary

Bacterial synthesis method, as a green and efficient nanocellulose preparation method, has broad development prospects. By optimizing bacterial strains, culture medium composition, culture conditions and extraction and purification processes, the yield and quality of bacterial cellulose can be further improved, laying the foundation for its application in various fields.