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201.
在玉米干秸秆中分别接种酵母菌、乳酸菌和纤维素分解菌,以筛选出适合玉米干秸秆发酵生产优质粗饲料的理想菌株。结果表明,对秸秆粉处理30d后,乳酸菌组发酵产物的酸碱度和氮损失均最低,即PH4.12,氨态氮和总氮比为6.4%;玉米秸秆粉发酵后感官评价得分最高的是乳酸菌组;酵母菌组,乳酸菌组,纤维素分解菌组的乙酸含量分别为33.35mg/mL、15.57mg/mL和6.32mg/mL,组间差异显著(P〈0.05);乳酸含量分别为15.25mg/mL、30.89mg/mL和1.37mg/mL,组间差异显著(P〈0.05);丁酸含量分别为5.35mg/mL,3.11mg/mL和20.53mg/mL,组间差异显著(P〈0.05)。试验结果提示,在本试验条件下,乳酸菌是玉米干秸秆发酵的最佳菌株。 相似文献
202.
乳酸是一种极具发展潜力的精细化学品,需求量仅次于柠檬酸。目前以纤维素生物质为基质生产乳酸的方法是生产乳酸的重要发展方向。同步水解技术生产乳酸克服了现有的使用纤维素酶水解制备乳酸等方法成本高、发酵菌种有待进一步筛选及发酵条件的控制等难点,具有明显的优势。 相似文献
203.
A 3 125 bp cellulose synthase gene, PtoCesA1, which has a 98% identity to PtrCesA1 from Populus tremuloides, was cloned from cDNA prepared from secondary xylem of P. tomentosa. Four anti-expression vectors with different fragments of PtoCesA1, named as pBIPF, pBICC1, pBIPR and pBIBR, were constructed. Some traits of transformed tobacco of pBICC1, pBIPR and pBIBR
differed from wild types, such as small leaves, “dwarf” phenotype and thinner xylem and fiber cell walls than wild plants
consistent with a loss of cellulose. It indicated that the growth of transgenic tobacco was restrained by the expression of
anti-PtoCesA1. Transgenic tobacco was obtained and the contents of cellulose and lignin were analyzed as well as the width and length of
fiber cells, and xylem thickness for both transgenic and control plants. Transformed tobacco showed a different phenotype
from control plants and it implied that PtoCesA1 was essential for the cellulose biosynthesis in poplar stems.
[Supported by the Hi-Tech Research and Development Program of China (863) (2001AA244060 and 2003AA244020) and National Basic
Research Program of China (973) (J1999016003)] 相似文献
204.
Residual wood meal after extraction of milled wood lignin (WMEM) ofEucalyptus globulus was extracted with alkali and LiCl/N,N-Dimethylacetamide (DMAc). These agents dissolve mainly hemicellulose and cellulose, respectively. The extractability of WMEM in alkali solutions was influenced by the degree of swelling of the cellulose. Under good swelling conditions, considerable amounts of cellulose and lignin were extracted with the hemicellulose. Maximum extractability was about 60% of the WMEM under optimum conditions (3 M or 5 M LiOH or 3M NaOH solution). Some portion of cellulose was extracted with LiCl/DMAc at room temperature. Thus, lignin inE. globulus WMEM was divided into three fractions: hemicellulose-lignin fraction, cellulose-lignin fraction, and insoluble-lignin fraction.Part of this work was presented at the 49th annual meeting of the Japan Wood Research Society, Tokyo, April 1999; and at the 50th annual meeting of the Japan Wood Research Society, Kyoto, April 2000 相似文献
205.
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207.
以松墨天牛幼虫为实验材料,研究了其肠道内纤维素酶的组成和酶解动力学特征等。结果表明,松墨天牛幼虫肠道内有完整的纤维素酶系,其中以C1酶活性最强,Cx酶次之,β-1,4-葡萄糖苷酶活性最弱;C1酶、Cx酶和β-葡萄糖苷酶3者的最适作用温区分别为35~55、45~55、40~50℃,最适pH值分别为5.0、5.6、5.0;Cx酶具有最强的热稳定性(65℃,2h),C1酶次之(55℃,2h),β-1,4-葡萄糖苷酶最低(50℃,1h)。此外动力学参数比较揭示,C1酶具有最大的Vmax和km,分别为1.0838和0.7632,β-1,4-葡萄糖苷酶和Cx酶分别具有最小的Km(0.1832)和Vmax(0.4339),但β-萄糖苷酶具有最大的酶解初速度(0.5938)。 相似文献
208.
209.
Shohei Kaneko Katsuhiko Yoshitake Shuji Itakura Hiromi Tanaka Akio Enoki 《Journal of Wood Science》2005,51(3):262-269
The degradation of wood, filter paper cellulose, and a lignin-substructure model, was measured in cultures of seven fungi usually regarded as brown-rot fungi. Hydroxyl radical production and the accumulation of oxalic acid in the cultures were also measured. Four of the fungi, Gloeophyllum trabeum, Tyromyces palustris, Laetiporus sulphureus, and Postia placenta, were typical brown-rot fungi, in that they preferentially degraded and eliminated the polysaccharides in wood and produced large amounts of hydroxyl radical. The rates of hydroxyl radical generation in cultures of the four fungi were directly proportional to the degradation rates of wood, cellulose, and the lignin-related compound, and inversely proportional to the amount of oxalic acid in the cultures. Two of the fungi, Daedalea dickinsii and Lentinus lepideus, did not degrade any of the substrates significantly and produced very little hydroxyl radical. Coniophora puteana had the highest rate of cellulose degradation, but did not degrade wood or the lignin model significantly and produced only negligible amounts of hydroxyl radical. These results indicate that brown-rot fungi produce large amounts of hydroxyl radical for the degradation of wood and crystalline cellulose. 相似文献
210.
Study of crystalline behavior of heat-treated wood cellulose during treatments in water 总被引:1,自引:0,他引:1
The crystalline behavior of heat-treated wood cellulose treated at 85% relative humidity (RH), in water, or boiled in water after heat treatment was investigated. The normal increased crystallinity was significantly depressed for samples that were oven-dried and then treated in 85% RH or in water. In the case of boiling-water treatment, a more pronounced increased in crystallinity was initially observed, which then decreased gradually. The crystallinity decreased more than untreated wood for samples that were heat treated for long periods and was slightly higher than the decreased crystallinity from the beginning of the above two treatments. On the other hand, no significant change in crystallinity was observed for samples of increased crystallinity or decreased crystallinity that were treated under high-moisture conditions, for all three treatments. The results show that the crystalline state of wood cellulose heat treated under oven dry or high-moisture conditions behave differently if treated in water after heat treatment. Results suggested that the mechanism of crystallization might be different for samples that are subjected to heat treatment under oven-dry and high-moisture conditions. 相似文献