Cellulose Production in Escherichia coli

Cellulose Production in Escherichia coli

Gizem Buldum, Alexander Bismarck, Athanasios Mantalaris

Abstractâ?? Over the last 30 years, attention has been paid to bacterial cellulose (BC). BC exhibits unique physical, chemical and mechanical properties when compared to plant-based cellulose, including high purity and biocompatibility. It is currently being used in the production of a wide variety of products such as paper, tissue- engineering products, electronics, biomedical devices, textiles, and food. Although Acetobacter xylinum is the most efficient producer of BC, it has many weaknesses such as long doubling time compared to most other bacteria, low productivity and its susceptibility to culture conditions. These limit the cost-effective production of BC. E.coli is an industrially attractive microorganism because it is a well- characterized host for protein expression and it has a significantly high growth rate. Herein, E. coli C41 (DE3) was selected as the host organism for the expression of bacterial cellulose synthase operon (bcs) of A.xylinum. The expression system was created using the pET-Duet1 carrying bcs operon (bcsABCD) and pCDF carrying upstream of the bcs operon. The upstream region of the bcs operon contains two genes: cmcax (encoding endo-β-1,4-glucanase) and cppAx (encoding cellulose complementing protein). All bcs genes were successfully transferred and expressed in E.coli C41 (DE3). The cells were cultured in LB medium at 37Ë?C and 180 rpm before IPTG induction. Following 0.05 mM IPTG induction, culture temperature shifted to 23Ë?C. After 24 hour culturing, cellulose production was obtained with a yield of 0.026 g/L. Cellulose samples were analyzed by FTIR spectra and scanning electron microscopy. SEM images clearly showed the shape and size distribution of the microfibrils. The microfibrils have lengths of more than 800-1000µm and diameters of the fibres are between 10â??20 µm. The expressions of bcs proteins were analysed by SDS page. The system stability was also monitored by plasmid stability test. The percentage of plasmid harboring cells was obtained 98% of the total viable cells even after 24-hr culturing. This proves that the system has been created for BC production is consistent. This study is novel in functional BC production in E. coli by the transfection of the cellulose production ability of A. xylinum and a big step to create valuable strains for the effective production of BC. BC productivity is affected by many factors such as the composition of the culture medium, environmental factors (pH, temperature, dissolved oxygen content) and the type of cultures used (culture flasks, agitated fermenters). In order to increase the yield of production in E. coli, culture conditions should be optimised by further studies. [1-3].
Keywordsâ?? Bacterial cellulose, E.coli, biopolymer, recombinant expression system

G.Buldum is with Imperial College London, Department of Chemical Engineering, London SW7 2AZ, UK (phone: +44 (0)20 7594 1224; e-mail: g.buldum11@ imperial.ac.uk).

A.Bismarck was with Imperial College London, SW7 2AZ, UK. He is now with Institute of Materials Chemistry and Research, Faculty of Chemistry, University of Vienna, Währinger Strasse 42, 1090 , Vienna , Austria (phone:

+43 (1) 4277 71301; e-mail: alexander.bismarck@univie.ac.at) A.Mantalaris is with the Imperial College London, Department of

Chemical Engineering, SW7 2AZ, London UK (phone: +44 (0)20 7594 5601;

e-mail: a.mantalaris@ imperial.ac.uk).

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