| Summary: | 碩士 === 中國文化大學 === 生物科技研究所 === 100 === This study investigates the effect of agricultural waste extract and alternative carbon/nitrogen sources on bacterial cellulose (BC) production of Acetobacter xyliunm (BCRC 12334). The application of rumen bacterial cellulolytic system on agricultural waste biomass convertion as A. xylinum production substrate was also investigated.
The first objective was based on the HS medium, it indicated that the BC dry matter yield was higher when initial was between pH 6.0 and 7.0. The result of carbon sources effect on the BC production suggested that single sucrose supported the better BC production (3.53 g/L). However, the highest BC production was obtained when glucose and fructose was used as the mixed carbon source (5.32 g/L). The nitrogen sources test showed that aspatic acid, glutamic acid, and soy protein isolate could replace peptone to support BC production. The highest BC yield was obtained when 15 g/L soy protein isolate (3.32 g/L) as nitrogen source.
The result of the sugar analysis showed that agriculture waste extract from the pineapple peel (PP) (Gloucose 18%, Fructose 27%, Sucrose 55%) had high potential to replace the production medium of A. xyliunm to produce BC., The maximum BC production (11.06 g/L) was found after adjusting the pH of pineapple peel extract between pH 5.5 to 6.0. Addition the mixture of aspatic acid and glutamic acid (2 g/L, 1：1) or soy protein isolate to pineapple peel extract significantly improved the yield of BC(P<0.05). Furthermore, addition pineapple peel with 5 g/L soy protein and pre-incubation for 16 hr resulted in higher BC production (14.24 g/L) (P<0.05).
The second objective of this study was to apply rumen bacterial cellulolytic degradation system on agricultural waste biomass to convert biomass as carbon source for A. xylinum BC production. Biomass including pineapple peel (PP), watermelon peel (WP), napiergrass (NG) and cabbage leaf (CL) were used in this study. The substrate incuced enzyme models from Fiberobacter succinogenes S85 indicated that WP and CL residues stimulated the exoglucanase activity significantly, but WP and NG residues stimulated the hemicellulase activity. Thereducing sugar and glucose production result suggested that PP and NG had higher cellulosic biomass conversion value. The commercial enzyme simulation result also indicated that the mixed enzyme model also improved the sugar conversion efficiency. Owing to the sugar utilization priority of A. xylinum growth and BC production, the agriculture wastes PP and NG after mixed enzyme model treatment were suitable for replacing the carbon source in A. xylinum growth and BC production. It suggested that rumen bacterial cellulolytic degradation model had potential to improve the value of the agricultural waste and reduce the pollution problem.
Key Words: bacterial cellulose, rumen bacteria, agriculture waste, carbon source, nitrogen source
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