Team:TUST China/Description

Team:TUST China 2017

Description

In this section, we describe the background and our bacterial cellulose project in brief.
We advise you to have a quick overall understanding of our project before viewing result pages.

What is Bacterial Cellulose ?

  • Cellulose is a major component of natural plant cellulose and plant cell wall; it covers 1/3 to 1/2 of plants’ dry weight and is the largest conservation pool of polysacchrides. Cellulose also exists in numerous lower level plants, some lower level animals and bacteria. Bacteria synthesizing cellulose was first reported by Brown in 1886. Bacterial cellulose is pure cellulose secreted by microorganism and its molecular composition shows no differences compared with normal cellulose. They are all β-D-glucose linked by β-1,4-glycosidic linkage forming linear chain. These linear chains,as known as β-1,4-dextran are paralleled ,branchless and exhibits no alpha helical conformation.The main differences between them is that bacterial cellulose doesn’t contain other polysacchrides such as hemicellulose and plant cellulose contains lignin, hemicellulose among others.

Character of Bacterial Cellulose

  • In terms of chemical property, bacterial cellulose are the same with those from plants and seaweeds. However, as a new-type of bio-material, bacterial cellulose possesses many unique properties[1]
    • 1)High degrees of crystallinity and chemical properties. 100% cellulose, doesn’t contain any hemicellulose, lignin, components of cell walls so the purification process is easy.
      2) High degrees of tensile strength and elasticity modulus. After washing and drying, the Young's modulus of bacterial cellulose can reach to 10MP ; after autoclave, the Young’s modulus of it can reach to 30MP, 4 times stronger than organic synthetic fibers.
      3) Outstanding water binding property. Its internal structure have many poles, it has fine air and water permeability. Capable of absorbing water 60-700 times of its own dry weight. Therefore, it possesses wonderful water retention quality and wet-maintaining quality.
      4) Outstanding shape-retention tear-resistance quality. Bacterial cellulose is 5 times more tear-resistant than polyethylene and polyvinyl chloride film
      5)fine bio-compatibility and Biodegradability.
      6) Functional tunability during biosynthesis. Adopting different methods of culturing for Acetobacter, such as in static or spinning environment, can result to different advanced structure of bacterial cellulose. Through adjusting fermentation conditions, collecting bacterial cellulose with different chemical properties is also possible.

Application of Bacterial Cellulose

  • Since the discovery of bacterial cellulose 100 years ago, its application is limited due to low yield and lack of understanding to its physical property. In recent decades, as scientists learn more about bacterial cellulose’s biosynthesis mechanism and refine its fermentation condition, the industrialization of bacterial cellulose is accelerated. Owing to its excellent characteristic in purity, water retention, physics, and mechanical properties, bacterial cellulose is now promising bio-material in business world receiving attention worldwide. Until now, the cost of producing bacterial cellulose is still high for which its application still focus on high-value added product.

Application in Medical Fields

  • Bacterial cellulose possesses good bio-compatibility ,tensile strength and degree of hydration, which is good for skin tissue growing and contamination-resistance[2,3]. Physical, chemical, mechanical and biomedical test of refined bacterial cellulose have proved that it possesses some unique quality such as bioactivity, biodegradability, bio-compatibility and is not irritable. Especially, the good mechanical tensile strength makes it possible to be new-type of bio-medical material. Dieter[4] has conducted research on using bacterial cellulose as artificial vessel in microsurgery. In his research, he found out that this material has a promising future in clinical application. For instance, it can function as vector for slow-release carrying various medicine, which is beneficial to applying medicine on skin surface and promoting wound healing and recovery. The up side of this material is that it can alleviate pain for the patience and has good adhesivity, which help prevent bacterial invading and contaminate the wound. It is permeable to water and electrolyte. Additionally, compared to tradition material, bacterial cellulose require shorter time to process and the the regeneration of healthy skin is faster.
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References

[1] Napoly C.， Dazzo F.， Hubbel D. (1975)Production of cellulose microfibrils by rhizobium [J]. Applied Microbiol,30：123-131

[2] Gatenholm, P. and Klemm, D. (2010) Bacterial nanocellulose as a renewable material for biomedical applications. MRS Bull. 35, 208–213

[3] Lin, S-P. et al. (2013) Biosynthesis, production and applications of bacterial cellulose. Cellulose 20, 2191–221

[4]Dieter Klemm， Dieter Schumann，(2001) Ulrike Udhardt and Silvia Marsch. Bacterial synthesized cellulose—artificial blood vessels for microsurgery [J]. Progress in polymer science26(9)：1561-1603

[5]Peter Ross， Raphael Mayer,and Moshe Benziman.(2005) Cellulose Biosynthesis and Function in Bacteria [J] . Microbiological Reviews，55(1)：35-58

[6] White,A.P.etal.(2010)AglobalmetabolicshiftislinkedtoSalmonella multicellular development. PLoS ONE 5, e11814