共查询到20条相似文献,搜索用时 171 毫秒
1.
2.
3.
4.
研究了共存碳源对克雷伯氏菌NIII2以蔗糖为主要碳源发酵产絮凝剂的影响.实验结果表明:柠檬酸为共存碳源时,克雷伯氏菌NIII2分泌絮凝剂过程中容易产酸,使得絮凝剂的产量和碳源转化率都较低.当丁二酸、乙酸、乳酸为共存碳源时,发酵液pH均高于7.5,絮凝剂产量有所提高,最高可达10.87g/L,碳源转化率也较高,为43.48%.与柠檬酸为共存碳源相比,当投加丁二酸时,克雷伯氏菌NIII2所产微生物絮凝剂中蛋白质与糖含量比值提高了33%,絮凝剂的Zeta电位值由-60.00 mV升高至-28.07 mV,絮凝剂分子粒径广泛分布在0~300μm之间且大粒径分子所占比例增加,聚合度加大,絮凝剂表面形貌呈现结块团状无定型结构,从而提高絮凝剂的活性和性能.该微生物絮凝剂投加量为4.0 mg/L,对2 g/L高岭土的SS去除率可达97.3%. 相似文献
5.
6.
7.
筛选出一株针对屠宰废水有高效絮凝活性的微生物絮凝剂产生菌,并对其所产微生物絮凝剂D6进行单因子絮凝条件优化和正交试验优化得到最佳絮凝条件。絮凝条件包括:微生物絮凝剂D6投加量、pH、金属离子种类、1%CaCl2投加量。试验中发现碱性环境是微生物絮凝剂D6发挥絮凝活性的前提,表明微生物絮凝剂D6分子链的充分伸展对絮凝作用起决定因素,因此微生物絮凝剂D6的絮凝机理为吸附架桥作用。其最佳絮凝条件为微生物絮凝剂D6的投加量为25mL·L-1,1%CaCl2投加量55mL·L-1,pH为8。在最佳絮凝条件下,絮凝率为96.6%,浊度去除率为97.8%,SS去除率为92.6%。 相似文献
8.
9.
从广西大学食用菌废弃料中分离出7株絮凝剂产生菌,以发酵液对高岭土悬浮液絮凝效果为指标衡量其絮凝活性及产絮凝剂能力,经过初筛与复筛,筛选到一株絮凝剂高产菌F00,初步确定属曲霉属(Aspergillus),并对其产生絮凝剂的条件进行优化. 相似文献
10.
利用固定化菌半连续生产微生物絮凝剂的研究 总被引:4,自引:0,他引:4
利用多孔聚酯泡沫为载体,进行了微生物絮凝剂产生菌的固定化条件优化和半连续生产絮凝剂的研究。研究发现,利用多孔聚酯可吸附固定XN1菌丝细胞,且能够较长时间保持高的活性。选择载体颗粒0.5cm×0.5 cm×0.5 cm,固液比为6 g/L,接种量105个孢子/mL培养基可达到较好的固定化和产絮凝剂效果。利用最佳固定化条件进行絮凝剂的摇瓶半连续生产实验发现,在最佳条件下,固定化XN1菌产絮凝剂可连续达12批次,且絮凝活性均在90%以上,说明利用多孔聚酯泡沫颗粒作为固定化载体,连续生产絮凝剂的方法是可行的。且和游离菌生产絮凝剂相比,生产效率可提高77.78%。 相似文献
11.
12.
13.
14.
H.-R. GREGORIUS 《Biological journal of the Linnean Society. Linnean Society of London》1984,23(2-3):157-165
For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment. 相似文献
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment. 相似文献
15.
16.
17.
18.
In this article, we systematically review Dr. Wu Lien-Teh's academic achievements and outstanding contributions in the prevention and control of the plague epidemic in northeast China and introduce the development of the earliest public health epidemic prevention system in China in order to commemorate the 140th anniversary of Dr. Wu Lien-Teh's birth. We hope that this article will provide insights into the effective prevention and control of emerging infectious diseases as well as the current worldwide pandemic of COVID-19, facilitating the improvement and development of public health systems in China and around the globe. 相似文献
19.