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Microbiological and molecular characterization of cellulose producing Gluconacetobacter sp

Usha Rani, M. (2011) Microbiological and molecular characterization of cellulose producing Gluconacetobacter sp. Doctoral thesis, University of Mysore.

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Abstract

Biodegradable polymers are in great demand due to their environmental friendly nature. Polysaccharides from microbial source are most commonly used. Microbial polysaccharides are produced by various genera of bacteria having wide variety of applications. The production of bacterial cellulose (BC) is a characteristic feature of Gluconacetobacter sp. In a liquid medium Gluconacetobacter produces BC in the form of floating pellicle comprising of cellulose, entrapped cells and other media ingredients. In the present work BC producing bacterium was isolated, characterized and identified. Based on morphological, biochemical and molecular methods - the isolate was identified as Gluconacetobacter hansenii. The purified BC film produced by native isolate was characterized for its structural and molecular properties by GC, scanning electron microscopy, FT-IR, 13C NMR. The results indicate BC to be made up of only glucose monomers. Physico-mechanical, barrier properties, thermal characteristics of melt, decomposition were analysed by differential scanning caloriemetry and thermal stability by thermo gravimetric analysis. The nutritional and cultural conditions for the enhanced production of BC were optimized from the native isolate G. hansenii UAC09. To economize the BC production, agro wastes like coffee cherry husk extract, and molasses as carbon source and corn steep liquor as nitrogen source were exploited. High yield of BC was achieved from a combination of coffee cherry husk extract and 8% corn steep liquor. Response surface methodology was used for optimization of media components. To understand the utilization of pectin and polyphenols from CCH by G. hansenii UAC09, production aspects of pectinases, tannase and polyphenol oxidase enzymes were studied. ix Experiments were carried out to understand the changes in sugars and polyphenols during the course of fermentation in the coffee cherry husk extract culture broth and cellulose produced. For the improvement of packaging properties, the BC films were coated with vinyl resin - carboxyl modified vinyl chloride (VMCH, food grade) and its properties were studied. The studies conclude that native isolate G. hansenii UAC09 has a high potency to produce BC. The BC produced exhibited good physico-mechanical properties and after coating a fair sealing property.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: bacterial cellulose, Gluconacetobacter, Biodegradable polymers, Microbial polysaccharides
Subjects: 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 27 Polymer Chemistry
500 Natural Sciences and Mathematics > 07 Life Sciences > 04 Microbiology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 14 Nov 2013 09:53
Last Modified: 22 Oct 2018 09:21
URI: http://ir.cftri.com/id/eprint/11301

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