Enzyme production by solid-state fermentation of Trichoderma reesei and Aspergillus niger for saccharification of napier grass

• Main Authors: Jian-Wen Wang, 王建文
• Other Authors: 余琬琴
• Format: Others
• Online Access: http://ndltd.ncl.edu.tw/handle/rzk423

碩士 === 國立臺北科技大學 === 有機高分子研究所 === 104 === Napier grass and okara (or soy pulp) were used as the substrate for the production of cellulolytic enzymes by Trichoderma reesei (ATCC 56765) and Aspergillus niger (ATCC 10864) via solid-state fermentation. To overcome the low -glucosidase activity problem of T. reesei monoculture, two strategies were investigated: (1) mix culture approach, i.e., co-cultivation of T. reesei and A. niger; (2) enzyme mixture approach, i.e., mixing crude enzyme extracts from monocultures of T. reesei and A. niger. Both approaches were able to increase the level of -glucosidase activity compared to T. reesei monoculture. The cellulosic enzyme activities achieved by the mix culture approach were 13.1 ± 1.3 FPU/g dry substrate and 13.9 ± 1.2 CBU/g dry substrate, while the enzyme mixture approach attained 12.4 ± 1.1 FPU/g dry substrate and 21.9 ± 0.5 CBU/g dry substrate. The hydrolysis efficacy of our crude enzyme extracts was compared to commercial enzyme preparations at a cellulase loading of 10 FPU/g-glucan and 2 wt% substrate concentration. Three different substrates were used, i.e., pristine (un-pretreated), alkaline pretreated (AP), and alkaline hydrogen peroxide pretreated (AHP) napier grass. The pretreatments partially removed lignin and increased the proportion of cellulose in the substrates, which helped the conversion of glucan. Our crude enzyme extracts, whether from the mix culture or the enzyme mixture approach, show higher hydrolysis efficiency than the commercial enzyme preparations. The highest glucose yield of 44 % was obtained using AHP napier grass as the substrate and the crude extract from the enzyme mixture approach, which was more than twice the glucose yield achieved by the commercial enzyme preparations.