Application of the Mixture Design to Design the Formulation of Pure Cultures in Tibetan kefir

To obtain the optimization formulation of pure cultures in Tibetan kefir, the influence of the different mixtures of five strains in the pure cultures in Tibetan kefir on the flavor components in fermented milk was studied using the mixture design. The regression model on microorganism composition and main metabolites was established. The results suggested that the predictable production of lactate reached the maximum of 8.16 g L-1, while the most predictable production of diacetyl, ethanol, and CO2 were 77.23 mg L-1, 4259 mg L-1, and 2.12 g L-1, respectively. Based on these, the response values that satisfied all expectations were optimized, and the most excellent combination was Lactococcus lactis 27%, Leuconostoc mesenteroides 37%, Lactobacillus kefiri 11%, Lactobacillus casei 10%, and Kluyveromyces rnarxianus 15%. With the aid of analysis software （Design-expert 6.0.5）, the formulation of pure cultures in Tibetan kefir can be optimized for several responses and the best formulation can be obtained.     

苹果属植物的无融合生殖能力研究

对２０个苹果属植物种类花粉生活力测定、去雄不授粉套袋，不去雄不授粉套袋及人工杂交表明，在多倍体种类中，除海棠花外，均无花粉，属兼性无融合生殖。四倍体种类的无融合生殖能力不低于三倍体种类。在二倍体种类中，除马尔康海棠外，均有花粉和较高生活力，无融合生殖能力，仅珠眉海棠和花叶海棠有较低的座果率和结种率。     

转基因实验中愈伤组织受体培养和工厂化扩增技术

介绍了以愈伤组织作转化受体的培养技术要点，对实现转基因体系工厂化的问题进行了讨论，认为建立工厂化转基因体系的关键是改进某些组织培养技术路线来提高繁殖系数．     

真菌诱导子对南方红豆杉细胞生长及紫杉醇合成的影响

用真菌诱导子处理南方红豆杉(Taxus chinensis var.mairer)悬浮细胞,测定细胞生长指数、紫杉醇含量及其细胞酶活的变化,初步探讨真菌诱导子对南方红豆杉悬浮细胞生长的影响。结果表明,在细胞悬浮培养第8天加入100μg/m L真菌诱导子,可明显增加悬浮细胞的生物量,紫杉醇的含量也有提高;添加真菌诱导子能抑制细胞多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)的活性,有利于细胞生长。     

Effect of supplementation of calf starter with fennel powder on performance,weaning age and fermentation characteristics in Holstein dairy calves

The objective of this experiment was to investigate the effects on performance, weaning age and rumen fermentation characteristics in Holstein calves when fennel powder was added to their starter diets. Thirty Holstein calves with a mean birth weight 40 kg (SD = 0.5) were allocated randomly to one of the following experimental diets: (i) control (starter diet without fennel powder), (ii) starter diet containing 0.4% of fennel powder and (iii) starter diet containing 0.8% of fennel powder (DM basis). The effect of treatments on mean dry matter intake was significant (p < 0.05) in the post‐weaning and total experimental periods. Average daily weight gain before (0.38, 0.49 and 0.47 kg/day) and after (0.6, 1.01 and 0.83 kg/day) weaning and during the entire study (0.45, 0.7 and 0.58 kg/day) was influenced by diets of 1, 2 and 3, respectively (p < 0.05). Maximum daily weight gain and the best feed conversion ratio were achieved with 0.4% fennel powder. Mean weaning age of the calves supplemented with fennel powder was lower (p < 0.05) than that of the control group. Ruminal fluid pH in calves offered starter containing 0.8% fennel powder was lower (p < 0.05) compared to calves fed the other diets. Ammonia nitrogen content increased (p < 0.05) in the third week of feeding fennel powder. The mean concentration of total short‐chain fatty acids (SCFA) and propionate molar percentage in the ruminal fluid of the calves fed with the fennel powder were higher (p < 0.05) at 6 weeks and 2 weeks after weaning than control group; however, acetate‐to‐propionate molar ratio was lower (p < 0.05). The results showed that adding 0.4% fennel powder to the starter increased the propionate molar percentage in the rumen and improved the calf performance, allowing the calves to be weaned at an earlier age.     

不同颗粒开食料对早期断奶犊牛瘤胃发育及生长性能的影响

本试验将16头荷斯坦公犊牛随机分为两组:试验组饲喂添加苜蓿叶粉和膨化玉米的一号开食料和二号断奶过渡料,对照组饲喂未添加苜蓿叶粉和膨化玉米的三号开食料。60日龄时对犊牛生长性能进行测定分析,每组屠宰3头犊牛,测定瘤网胃重及容积、瘤胃乳头高度及宽度,结果显示:试验组的瘤网胃重及容积、瘤胃乳头及宽度高于对照组,差异显著(P<0.05);试验组犊牛日增重和体尺与对照组相比差异不显著(P>0.05)。提示在7~40日龄饲喂一号开食料、41~60日龄饲喂二号断奶过渡料在一定程度上促进了犊牛瘤胃组织的发育。     

乳酸杆菌抑制致病菌及生物保鲜发酵剂特性评价

以15株乳酸杆菌为研究对象,动物双歧杆菌乳亚种BB-12作为对照,研究它们对肠道致病菌的抑菌特性.结果表明:9株菌对5株指示菌均有较好抑制作用,2株菌对金黄色葡萄球菌、肠炎沙门氏菌、大肠杆菌和蜡样芽孢杆菌均有抑制作用;以抑菌效果、凝乳状态、产酸性能为指标,筛选出4株菌,与嗜热链球菌ST-21组合制备生物保鲜发酵剂;通过...     

硼钙营养对柠檬幼苗光合生理及根系活力的影响

采用二因素五水平回归最优设计、砂培，两种ｐＨ环境（ｐＨ１５．６～５．８，ｐＨ２７．６～７．８），研究了Ｂ，Ｃａ不同浓度对柠檬幼苗生长、叶片叶绿素含量、光合强度及根系活力的影响，建立了相应的数学模型。结果表明，Ｂ，Ｃａ缺乏或过量降低叶绿素含量和光合强度。叶绿素含量最大时的叶Ｃａ／Ｂ分别为ｐＨ１下４９１，ｐＨ２下２９３；光合强度最大时的叶Ｃａ／Ｂ分别为ｐＨ１下５２５，ｐＨ２下２８５。Ｂ，Ｃａ浓度适量下降提高了根系活力，而Ｂ，Ｃａ浓度过量抑制了其活力，碱性环境的根系活力明显低于酸性环境。