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Rasmussen MA Hespell RB White BA Bothast RJ 《Applied and environmental microbiology》1988,54(4):890-897
Highly methylated, long-chain celluloses strongly inhibited cellulose degradation by several species of cellulolytic bacteria of ruminal origin. Specifically, the inhibitory effects of methylcellulose on the growth of Ruminococcus flavefaciens FD1 were concentration dependent, with complete inhibition at 0.1% (wt/vol). However, methylcellulose did not inhibit growth on cellobiose or cellulooligosaccharides. Mixtures of methylated cellulooligosaccharides having an average degree of polymerization of 6.7 to 9.5 inhibited cellulose degradation, but those with an average degree of polymerization of 1.0 to 4.5 did not. Similar inhibitory effects by methylcellulose and, to a lesser extent, by methyl cellulooligosaccharides were observed on cellulase activity, as measured by hydrolysis of p-nitrophenyl-beta-d-cellobioside. R. flavefaciens cultures hydrolyzed cellulooligosaccharides to cellobiose and cellotriose as final end products. Cellopentaose and cellohexaose were cleaved to these end products, but cellotetraose was also formed from cellohexaose. Methylcellulose did not inhibit hydrolysis of cellulooligosaccharides. These data are consistent with the presence of separate cellulase (beta-1,4-glucanase) and cellulodextrinase activities in R. flavefaciens. 相似文献
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The oligosaccharides extracted from the roots of Arnica montana L., Artemisia absinthium L. and Artemisia dracunculus L. have been analysed by thin-layer and gel-permeation chromatography to assess their applicability as ‘guide’ substances for pharmacological activity. Differences observed in the oligosaccharide component composition of such extracts might be more related to the vegetative stage of the plants at time of harvest than to the species themselves. In addition to a series of non-reducing oligofructosides, a series of reducing inulin-type oligosaccharides was found at the initial stages of growth, whereas in later stages of growth only non-reducing oligofructosides were present. These differences have been related to different stages of biosynthetic activity within the plants. 相似文献