19-08-2014, 11:33 AM
The present work was undertaken with following objectives: i) Screening of Acetobacter strains for cellulose production ii) optimization of fermentative production by one factor-at-a-time and statistical approach iii) study of various metabolic precursors for enhanced production iv) purification and characterization of bacterial cellulose.
Bacterial cellulose, an exopolysaccharide produced by Acetobacter sp. is a homopolymer of glucose units linked together by -1 4 linkages. It is preferred over the plant cellulose for many applications such as manufacturing of ultrafiltration membrane, as cover membrane for glucose biosensors, as binders, as thickeners and, as an adhesive since it can be obtained in more pure form and exhibits a higher degree of polymerization and crystallinity index. It also has higher tensile strength and water holding capacity, making it more suitable for producing high fidelity acoustic speakers, high quality paper, and dessert foods. Fibrils of bacterial cellulose are about 100 times thinner than that of plant cellulose making it a highly porous material. This allows transfer of antibiotics or other medicines into the wound, and also serves as an efficient physical barrier against any external infection.
The present work was undertaken with following objectives: i) Screening of Acetobacter strains for cellulose production ii) optimization of fermentative production by one factor-at-a-time and statistical approach iii) study of various metabolic precursors for enhanced production iv) purification and characterization of bacterial cellulose.
Of the two strains, Acetobacter xylinum NCIM 2526 and Acetobacter hansenii NCIM 2529 screened for production of cellulose, A. hansenii NCIM gave more cellulose production and was selected for further study. In first step, optimization of cellulose production was carried out for pH, inoculum size, carbon source, nitrogen source and phosphate ions using one factor at-a-time followed by response surface methodology (RSM). One factor at-a-time method resulted in increase of cellulose production from 2.0 ± 0.09 g/l to 3.2 ± 0.14 g/l. Further increase in cellulose production from 3.2 ± 0.14 g/l to 6.2 ± 0.21 g/l was obtained using RSM. In the second step, effects of various amino acids and vitamins on fermentative production were studied.
Structural characteristics of bacterial cellulose were studied by using FT-IR and X-ray diffraction.
Thermal stability and morphology of cellulose was studied by using differential scanning colorimetry (DSC) and scanning electron microscopy (SEM). Furthermore, studies to determine the viscosity profile of fermentation broth during various stages of fermentation and molecular weight determination are in progress.