天然碱泥分离用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,从蔬菜土地壤中筛选出一株具有高絮凝活性的细菌,细菌生长过程中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强絮凝作用。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,最终确定为产气肠杆菌（Enterobacter aerogenes)。该菌株可以利用单糖尤其是葡萄糖产酸,并可利用果糖产酸,兼性厌氧。     

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％。     

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。     

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%。     

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。     

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。     

几株絮凝剂产生菌的特性研究

筛选到８３株絮凝剂产生菌,其中絮凝活性最高的四株分属于芽孢乳杆菌属、节细菌属、假单胞菌属、气单胞菌属。四株菌在生长过程中均可产生胞外絮凝物质,在最适培养条件下絮凝剂产量为０．５－０．９ｇ／Ｌ。纯化后的四种絮凝剂中,三种为核蛋白,一种为糖蛋白,均为高分子量物质（ＭＷ＞１０＾６）。四株菌均不含质粒。１２－３０ｇ／Ｌ的絮凝剂在１小时内对所有供试材料均有较好的絮凝效果。动物急性毒性实验表明。     

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)。     

微生物絮凝剂的菌种分离筛选及其产生条件的选择

本研究采用根瘤菌选择性培养基和稀释平板法,从广西大学校园罗汉松和相思树植物根瘤中总共分离出20株菌落光滑型菌株,并分别对其发酵物作絮凝试验.研究结果表明,从罗汉松根瘤中筛选出一株絮凝率较高的菌株,暂编号为P2.对P2进行形态学观察结果表明:其菌落圆形、凸起、光滑、无色透明,其细胞杆状、菌体大小为0.5×(1～2)μm,该类细菌为革兰氏阴性细菌、有糖被、无芽孢,周生鞭毛;测序分析表明其16S rDNA序列与Rhizobium sp.DV8 16S rDNA(DQ873665.1)同源性达98%以上;生长和产絮凝剂最佳条件如下:配方为甘露醇10%,K_2HPO_4 0.3%,酵母膏0.03%,NaCl 0.5%,(NH_4)_2SO_4 0.01%,脲0.03%液体培养基中,30℃,起始pH为7.0,转速为200 r/min条件下培养发酵72 h,产生的絮凝剂可使浓度为5 000 mg/L高岭土悬浮液在20 min内絮凝率最高为92%.     

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％。     

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.     

Strain selection for improvement of Bradyrhizobium japonicum competitiveness for nodulation of soybean

A Bradyrhizobium japonicum USDA 110-derived strain able to produce wider halos in soft-agar medium than its parental strain was obtained by recurrent selection. It was more chemotactic than the wild type towards mannitol and three amino acids. When cultured in minimal medium with mannitol as a single carbon-source, it had one thick subpolar flagellum as the wild type, plus several other flagella that were thinner and sinusoidal. Root adsorption and infectivity in liquid media were 50-100% higher for the selected strain, but root colonization in water-unsaturated vermiculite was similar to the wild type. A field experiment was then carried out in a soil with a naturalized population of 1.8 x 10(5) soybean-nodulating rhizobia g of soil(-1). Bradyrhizobium japonicum strains were inoculated either on the soybean seeds or in the sowing furrows. Nodule occupation was doubled when the strains were inoculated in the sowing furrows with respect to seed inoculation (significant with P<0.05). On comparing strains, nodule occupation with seed inoculation was 6% or 10% for the wild type or selected strains, respectively, without a statistically significant difference, while when inoculated in the sowing furrows, nodule occupation increased to 12% and 22%, respectively (differences significant with P<0.05).     

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）。     

Microbial selection strategies that enhance the likelihood of developing commercial biological control products

Research interest in utilizing microorganisms to create a microbial environment suppressive to plant pathogens has increased exponentially in recent years. Despite intense interest in developing biological control agents, relatively few antagonists have achieved ‘commercial product’ status. The fact that such a small proportion of active laboratory antagonists are developed into biological control products is partly due to several features common to microbial selection strategies that are widely utilized to obtain putative biological control agents: (a) relatively few candidate microorganisms are tested; (b) microbes are selected based on the results of an assay that does not replicate field conditions; and (c) the amenability of microbes to commercial development is excluded as a selection criterion. Selection strategies that enhance the likelihood of developing commercial biological control products are described. These include making appropriate choices regarding the pathosystem for biological control, the method of microbe isolation, and the method of isolate characterization and performance evaluation. A model system of developing a biological control product active against Gibberella pulicaris (Fries) Sacc. (anamorph: Fusarium sambucinum Fuckel), the primary causal agent of Fusarium dry rot of stored potatoes, is used to illustrate the proposed selection strategy concepts. The crucial importance and methodology is described, of selecting strains with enhanced potential for commercial development based on a strain exhibiting both favorable growth kinetics and bioefficacy when grown in commercially feasible liquid media. Received 06 February 1997/ Accepted in revised form 29 May 1997     

Rapid selection of microorganisms producing extracellular lipases]

A method for rapid selection of microorganisms producing extracellular lipases is described. The method is based on diffusion of the enzyme into agar containing olive oil. The hydrolysis zones revcal by 0,05--0,25% OSO4 solution.     

Strain selection and genetic variation in Gracilaria chilensis (Gracilariales, Rhodophyta)

Strain selection processes in seaweed often have assumed that sterile clones could be maintained for long periods in a diversity of environments without major genetic changes. However, clonal species such as Gracilaria chilensis exhibit intra-clonal variation in performance and ongoing studies suggest such changes may be due to rapid changes in DNA composition associated with growth, via mitotic recombinations. Therefore performance of a given ramet in this type of seaweed should be understood as the dynamic outcome of rapid reactions between the environment and the changing genotype of the selected strain. To evaluate this idea, we measured changes in genetic variability, as detected by DNA-fragment polymorphism using RAPDs-PCR, exhibited by clones of G. chilensis after two transfers to different environmental conditions (from field to controlled laboratory conditions and from the laboratory to large-scale tank culture). The transfer to laboratory conditions reduced the frequency of low similarity values and increased the frequency of intermediate similarity values in DNA banding patterns, suggesting the branchlets produced under controlled laboratory conditions have less genetic variability (evaluated as total DNA polymorphism) than plants recently collected in the field. Tank incubation reduced the total range of similarity and significantly increased the frequency of high similarity values. Results thus suggest the dynamic of genetic changes in vegetative clones of Gracilaria chilensis that is fast and strongly affected by the external environment. This revised version was published online in July 2006 with corrections to the Cover Date.