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不同水平蛋白质底物对猪结肠微生物体外发酵特性和菌体合成能力的影响 被引量:6
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作者 葛婷 孙巍巍 朱伟云 《动物营养学报》 CAS CSCD 北大核心 2016年第7期1998-2004,共7页
本试验旨在体外条件下,探究不同水平蛋白质底物对猪结肠微生物发酵特性的影响,了解猪结肠微生物对蛋白质的利用规律。以成年猪结肠内容物为微生物接种物,在结肠微生物发酵液中分别添加0(C组)、0.10(L组)、0.25 g/L(H组)酪蛋白水解物,厌... 本试验旨在体外条件下,探究不同水平蛋白质底物对猪结肠微生物发酵特性的影响,了解猪结肠微生物对蛋白质的利用规律。以成年猪结肠内容物为微生物接种物,在结肠微生物发酵液中分别添加0(C组)、0.10(L组)、0.25 g/L(H组)酪蛋白水解物,厌氧发酵不同时间点(3、6、9、12、18、24 h),分别测定累积产气量、p H及微生物蛋白、氨态氮、挥发性脂肪酸浓度。结果显示:1)发酵3、6 h时,L组和H组p H显著低于C组(P<0.05)。2)L组和H组累积产气量均高于C组。3)L组和H组各时间点微生物蛋白浓度均显著高于C组(P<0.05),6 h时H组又显著高于L组(P<0.05)。3)L组和H组各时间点氨态氮浓度均显著高于C组(P<0.05)。4)短链脂肪酸和支链脂肪酸浓度随着发酵时间延长而增加,同时随着蛋白质水平增加而增加。由此可见,蛋白质底物的添加促进了肠道微生物菌体合成,但是过多的蛋白质底物水平并不能进一步提高微生物蛋白浓度;随着蛋白质水平增加,肠道微生物发酵特性进一步提高。 展开更多
关键词 蛋白质水平 结肠微生物 发酵特性 菌体合成能力
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Recent advances in the molecular genetics of resin biosynthesis and genetic engineering strategies to improve defenses in conifers
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作者 唐巍 《Journal of Forestry Research》 SCIE CAS CSCD 2003年第2期171-179,共9页
Since the first terpenoid synthase cDNA was obtained by the reverse genetic approach from grand fir, great progress in the molecular genetics of terpenoid formation has been made with angiosperms and genes encoding a ... Since the first terpenoid synthase cDNA was obtained by the reverse genetic approach from grand fir, great progress in the molecular genetics of terpenoid formation has been made with angiosperms and genes encoding a monoterpene synthase, a sesquiterpene synthase, and a diterpene synthase. Tree killing bark beetles and their vectored fungal pathogens are the most destructive agents of conifer forests worldwide. Conifers defend against attack by the constitutive and inducible production of oleoresin that accumulates at the wound site to kill invaders and both flush and seal the injury. Although toxic to the bark beetle and fungal pathogen, oleoresin also plays a central role in the chemical ecology of these boring insects. Recent advances in the molecular genetics of terpenoid biosynthesis provide evidence for the evolutionary origins of oleoresin and permit consideration of genetic engineering strategies to improve conifer defenses as a component of modern forest biotechnology. This review described enzymes of resin biosynthesis, structural feathers of genes genomic intron and exon organization, pathway organization and evolution, resin production and accumulation, interactions between conifer and bark beetle, and engineering strategies to improve conifer defenses. 展开更多
关键词 Genetic engineering strategies Resin biosynthesis Bark beetles GENOMICS Molecular genetics
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