Cellulose is the major biopolymer on earth with tremendous economic importance
as it has been utilised in a multitude of industrial applications including tissueengineering
products, composite materials and electronics. It exhibits outstanding
physical and mechanical properties when compared to plant-based cellulose.
Although A. xylinum is the most efficient producer of bacterial cellulose (BC), its
long doubling time results in insufficient yields and high cost. In this study, a novel
and functional BC production system was developed by recombinant DNA
technology. The simultaneous expression of bacterial cellulose synthase operon
(bcsABCD) and its upstream operon (cmcax and ccpAx) was achieved by pBCS and
pCDF, respectively. Three different Escherichia coli strains were utilised as host
microorganisms: E. coli BL21 (DE3), E. coli HMS174 (DE3) and E. coli C41 (DE3). It
was verified that bcsABCD and the upstream operon were successfully cloned and
expressed in E. coli strains. Fermentation of genetically modified (GM) strains was
conducted at various IPTG concentrations (0.025, 0.05, 0.1, 0.2, 0.5 and 1.0 mM)
and various temperatures (22, 30, and 37 °C). BC production was achieved by
genetically modified E. coli HMS174 (DE3) in the presence of 0.025 mM IPTG at
22°C. GM E. coli C41 (DE3) accomplished the production when IPTG supplement
was lower than 0.2 mM at 22°C or 30°C. The products were characterised by SEM
and FTIR, which exhibited that morphology of product was stain-specific. Finally a
dynamic mathematical model was developed to design a fed-batch system
capturing characteristics incorporating acetate inhibition and cell death, which
allowed predicting glucose consumption, acetate production and induction time for
batch cultures, resulted in a volumetric productivity of 1.7 mg/L.h.
In conclusion, this thesis reports the development of a novel BC production system
by creating valuable cellulose-producing E. coli strains, resulting in a reproducible
and stable recombinant expression system for potential improvement of BC.