天然碱碱泥分离用微生物絮凝剂产生菌的筛选

为解决内蒙天然碱泥分离的问题,从土壤、污水和活性污泥中,经初筛得到的57株产絮凝剂菌株,均有絮凝活性。并通过复筛从中筛选出絮凝活性较高、性状相对更稳定的2株菌株W23和L42。细菌的全培养液对强碱性的天然碱碱泥具有较强絮凝作用,其平均絮凝率分别达到79.80%和87.96%。     

生物絮凝剂产生菌的分离与鉴定

通过多点采样,多次反复筛选,从旱田土壤中筛选出1株具有高絮凝活性的细菌。细菌生长过程均可产生具有絮凝作用的胞外分泌物,经实验对内蒙天然碱碱泥具有高絮凝作用。通过对菌株的个体形态特征、菌落形态特征、运动性进行观察;同时对其接触酶、氧化酶等生理生化指标进行了测试,最终确定为粪产碱杆菌（Alcaligenes faecalis)。     

天然碱碱泥分离用微生物絮凝剂产生菌的筛选*

为解决内蒙天然碱泥分离的问题,从土壤、污水和活性污泥中,经初筛得到的57株产絮凝剂菌株,均有絮凝活性。并通过复筛从中筛选出絮凝活性较高、性状相对更稳定的2株菌株W23和L42。细菌的全培养液对强碱性的天然碱碱泥具有较强絮凝作用,其平均絮凝率分别达到79.80％和87.96％。     

天然碱泥絮凝用微生物絮凝剂产生条件的研究

报道了内蒙天然碱碱泥絮凝用微生物絮凝剂适宜产生条件的研究结果。高糖低氮培养基有利于絮凝剂的产生。适宜摇床发酵条件为：初始PH值7．5－8．5,培养温度30℃,摇床转速180r/min,发酵60h;在摇床优化的培养条件的基础上进行5L罐放大试验,发酵周期缩短12h,絮凝活性提高了14．45％。     

一株絮凝剂产生菌的筛选鉴定及培养条件

从淤泥中筛选到1株高效微生物絮凝剂产生菌JX18,经过对其形态特征、生理生化特性、以及16SrRNA序列分析初步鉴定为荧光假单胞菌。该菌培养40h进入稳定期,48h时絮凝活性达到最大。进一步研究表明:菌株JX18最适培养基初始pH值7.0,培养温度30°C,摇床转速160r/min,最佳碳源和氮源分别为葡萄糖和蛋白胨。最适培养条件下,所产絮凝剂对高岭土悬浮液的絮凝活性达到90.56%。     

微生物絮凝剂产生菌的筛选及培养研究

从活性污泥中筛选出3株能产生高效絮凝活性的微生物,对其中1株TJ3进行其最佳培养条件及废水絮凝实验研究。结果表明TJ3的最佳培养条件为：以葡萄糖、蛋白胨作碳,氮源,初始pH值6～7,温度25～30℃,摇床转速120～160r/min,培养时间72h,可产生高絮凝活性的絮凝剂,对高岭土悬浊液絮凝率达92.4%,同时在最佳培养条件下,该菌所产絮凝剂对多种废水净化效果明显,尤其对净化分散兰染液,酵母菌菌液分离最为突出,絮凝率均在95%以上,具有较高的絮凝性能。     

竹红菌素产生菌的筛选与鉴定

通过多点采集、反复筛选,从野生竹黄子实体中筛选出1株产北醌类光敏色素的真菌。通过对菌株的个体形态特征、菌落形态特征进行观察,结合其显微结构特征最终鉴定为竹黄菌（Shiraia bambuscola)。     

一株生物絮凝剂产生菌的筛选及絮凝活性研究

从活性污泥中筛选到一株产絮凝剂的菌株WJ-100。该菌株产絮凝剂的适宜pH塑6．5。适宜温度为25℃～40℃,摇床速度为80～240r／min;Na^＋、K^＋、Ca^2＋、Fe^3＋均有较好的促絮凝作用,Ca^2＋尤为显著;WJ-100以多种糖类为良好碳源,絮凝率达99.2％、99．8％甚至100％;该菌株在高岭土悬液pH2．0～10．0范围均有较好的絮凝效果。WJ-100在较大的pH、温度、碳源、摇床速度、搅拌速度等范围内均具有很高的絮凝活性,显示出重要的研究和应用价值。     

生物滤塔体系好氧反硝化菌的分离鉴定与特性研究

从实验室生物滤塔填料的生物膜上, 经选择性培养基筛选, 分离出4株好氧反硝化菌。好氧状态下4种菌的40 h反硝化率均大于80%, 其中菌种A1反硝化率可达到99.05%。跟踪菌种反硝化过程中氮元素24 h变化过程, 发现4株菌除A1外都有亚硝酸根积累。菌种A1为短杆菌, 革兰氏阴性。生理生化特性研究与16S rDNA 序列测定(GenBank接受号DQ836052.1)初步判定菌种A1为假单胞菌Pseudomonas putida。适于菌A1生长的初始pH值是7.0左右, 温度30℃左右, 当DO大于2.0 mg/L时, DO的变化对菌种A1的反硝化效果影响很小。     

微生物絮凝剂产生菌的筛选与特性研究

从活性污泥中筛选到1株絮凝活性很高的菌株MY-88。研究结果表明,MY-88的初始培养pH为6.5~7.0,最适温度为25~35℃,最适碳源为葡萄糖;在摇床速度为180 r/min时,其絮凝率达100%。Na 、K 、Ca2 、Fe3 均有较好的促絮凝作用,其中Ca2 尤为显著,使絮凝率达99.6%。MY-88在较大的pH、温度、摇床速度、搅拌速度、水样pH等范围内均具有较高的絮凝活性,显示出良好的应用前景。     

细菌纤维素生产菌株的分离和菌种初步鉴定

从长膜的醋醅中分离出一株发酵生产细菌纤维素产量较高且稳定的醋酸菌M12。根据《常见细菌系统鉴定手册》和《伯杰氏细菌鉴定手册》第九版,对醋酸菌M12进行了形态和生理生化特征的分析、测定了G＋Cmol％含量,初步鉴定该菌为醋化醋杆菌木质亚种（Acetobacter xylinum subsp.xylinum,又称木醋杆菌）。     

Antagonistic natural selection revealed by molecular sex identification of nestling collared flycatchers

Natural selection may act in different directions during different life-history stages, or in different directions on different classes of individuals. Antagonistic selection of this kind may be an important mechanism by which additive genetic variation for quantitative traits is maintained, and can prevent populations or species reaching local adaptive peaks. This paper reports the results of a study of viability selection on morphological traits of nestling collared flycatchers Ficedula albicollis . Analyses performed without knowledge of the sex of nestlings suggested that no selection was occurring on these traits. However, using molecular sex identification with the avian CHD gene, it is shown that selection acts in different directions on male and female body size from fledging to breeding, apparently favouring relatively small males and large females. The results suggest that differential selection on male and female nestlings may contribute to purely phenotypic sexual size dimorphism in this species. These findings highlight the potential of newly developed molecular sexing techniques to reveal the consequences of an individual's gender for many aspects of its life history in taxa where gender cannot be determined on the basis of external appearance.     

The genetic consequences of selection in natural populations

The selection coefficient, s, quantifies the strength of selection acting on a genetic variant. Despite this parameter's central importance to population genetic models, until recently we have known relatively little about the value of s in natural populations. With the development of molecular genetic techniques in the late 20th century and the sequencing technologies that followed, biologists are now able to identify genetic variants and directly relate them to organismal fitness. We reviewed the literature for published estimates of natural selection acting at the genetic level and found over 3000 estimates of selection coefficients from 79 studies. Selection coefficients were roughly exponentially distributed, suggesting that the impact of selection at the genetic level is generally weak but can occasionally be quite strong. We used both nonparametric statistics and formal random‐effects meta‐analysis to determine how selection varies across biological and methodological categories. Selection was stronger when measured over shorter timescales, with the mean magnitude of s greatest for studies that measured selection within a single generation. Our analyses found conflicting trends when considering how selection varies with the genetic scale (e.g., SNPs or haplotypes) at which it is measured, suggesting a need for further research. Besides these quantitative conclusions, we highlight key issues in the calculation, interpretation, and reporting of selection coefficients and provide recommendations for future research.     

The conflict between natural and artificial selection in finite populations

Summary A single locus model of the interaction between natural selection and artificial selection for a quantitative character in a finite population, assuming heterozygote superiority in natural fitness but additive action on the character, has been studied using transition probability matrices.If natural selection is strong enough to create a selection plateau in which genetic variance declines relatively slowly, then the total response to artificial selection prior to the plateau will be much less than that expected in the absence of natural selection, and the half-life of response will be shorter. Such a plateau is likely to have a large proportion, if not all, of the original genetic variance still present. In selection programmes using laboratory animals, it seems likely that the homozygote favoured by artificial selection must be very unfit before such a plateau will occur. A significant decrease in population fitness as a result of artificial selection does not necessarily imply that the metric character is an important adaptive character.These implications of this model of natural selection are very similar to those derived by James (1962) for the optimum model of natural selection. In fact, there seems to be no aspect of the observable response to artificial selection that would enable anyone to distinguish between these two models of natural selection.     

抑制绿脓杆菌的放线菌株SM037的筛选、鉴定及发酵条件研究

从土壤样品中分离到一株对绿脓杆菌有抑制作用的放线菌SM037,初步鉴定为黄雀链霉菌黄雀变种S.canariesvar.canaries。对SM037进行液体发酵条件优化,实验表明,最适培养基配方(g/L)为:淀粉30~40,KNO32,K2HPO40.5,MgSO40.5,NaCl 0.5,FeSO40.01。抑菌活性物质的相对效价在发酵培养96-108h时达到最高峰。     

Exploring natural selection to guide breeding for agriculture

Climate change threatens reduced crop production and poses major challenges to food security. The breeding of climate‐resilient crop varieties is increasingly urgent. Wild plant populations evolve to cope with changes in their environment due to the forces of natural selection. This adaptation may be followed over time in populations at the same site or explored by examining differences between populations growing in different environments or across an environmental gradient. Survival in the wild has important differences to the objective of agriculture to maximize crop yields. However, understanding the nature of adaptation in wild populations at the whole genome level may suggest strategies for crop breeding to deliver agricultural production with more resilience to climate variability.     

鸡肾型传染性支气管炎病毒FX株的分离和鉴定

从自然发生的鸡肾病变型传染性支气管炎病例采集病死鸡肾脏为材料,通过接种9－11日龄SPF鸡胚尿囊腔,进行病毒的分离和传代,分离到1株病毒（FX）,敏感鸡人工感染后出现呼吸症状,剖检病鸡时大我鸡肾肿大并有尿酸盐沉积,病毒能死鸡胚和产生侏儒胚;病毒能干扰鸡新城疫病毒LaSota株在鸡胚中增殖,病毒经电镜观察,其大小在80－120nm之间,囊膜外有纤,病毒经IBV单抗ELISA检测呈强阳性反应。研究结果初步表明,FX毒株为肾型IBV。     

Microbiology of Lonar Lake and other soda lakes

Soda lakes are saline and alkaline ecosystems that are believed to have existed throughout the geological record of Earth. They are widely distributed across the globe, but are highly abundant in terrestrial biomes such as deserts and steppes and in geologically interesting regions such as the East African Rift valley. The unusual geochemistry of these lakes supports the growth of an impressive array of microorganisms that are of ecological and economic importance. Haloalkaliphilic Bacteria and Archaea belonging to all major trophic groups have been described from many soda lakes, including lakes with exceptionally high levels of heavy metals. Lonar Lake is a soda lake that is centered at an unusual meteorite impact structure in the Deccan basalts in India and its key physicochemical and microbiological characteristics are highlighted in this article. The occurrence of diverse functional groups of microbes, such as methanogens, methanotrophs, phototrophs, denitrifiers, sulfur oxidizers, sulfate reducers and syntrophs in soda lakes, suggests that these habitats harbor complex microbial food webs that (a) interconnect various biological cycles via redox coupling and (b) impact on the production and consumption of greenhouse gases. Soda lake microorganisms harbor several biotechnologically relevant enzymes and biomolecules (for example, cellulases, amylases, ectoine) and there is the need to augment bioprospecting efforts in soda lake environments with new integrated approaches. Importantly, some saline and alkaline lake ecosystems around the world need to be protected from anthropogenic pressures that threaten their long-term existence.