| Summary: | 碩士 === 中興大學 === 食品暨應用生物科技學系 === 95 === Preliminary screening twelve Acetobacter strains in this study, Gluconacetobacter sp. C07 had a better bacterial cellulose(BC) yield and cellulose-pellicle integrity than others. Therefore we chose Gluconacetobacter sp. C07 as the fermentative bacterium and determined the optimal fermentation conditions for the bacterial cellulose production in SH medium .
To optimalize the fermentation conditions, we used bacterial culture that activied by static incubation and a 10 % (v/v) inoculum size to study the effect of temperature and pH on BC yield. Results indicated that 30℃ and the higher initial substrate pH (pH = 6.0) could result in a better BC yield.
To investigate the effect of substrate compositon on BC yield, the concentrations of two factors (sucrose and yeast extract) were statistically estimated by Response Surface Methodology (RSM). The optimization fermentation condition for the largest BC yield (1.82 cm) by Gluconacetobacter sp. C07 grown in the SH medium is that added sucrose and yeast extract ( 5.87 and 1.81 g/100ml respectively) in SH medium and initial substrate pH 6.0 at 30℃ for 12 days under static condition. The practical tests by using optimal condition can produce the BC with the similar yield (1.81 cm).
For the physical and mechanical properties, the cellulose-pellicle from optimization fermentation codition in this study was compared with cellulose-pellicle from the market. Results showed that the cellulose-pellicle in this study was higher in syneresis, water-holding capacity, water content, fracturability and adhesiveness than that from market, and hardness, springiness, cohesiveness, gumminess, cheesiness, resilience were lower than the cellulose-pellicle from the market.
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