Formation of micella containing solubilized sterols during rehydration of active dry yeasts improves their fermenting capacity     

Soubeyrand V  Luparia V  Williams P  Doco T  Vernhet A  Ortiz-Julien A  Salmon JM 《Journal of agricultural and food chemistry》2005,53(20):8025-8032

During their rehydration in aqueous media, active dry yeasts (ADY) may be supplemented with inactive yeasts, yeast derivatives, or other optional complementary nutrients to improve their fermentation capacity. We found that yeast sterols solubilized in situ during ADY rehydration were particularly efficient for stimulating the fermenting capacity of ADY. Spontaneous solubilization of sterols during rehydration occurred by the formation of micelles by membrane phospholipids and specific cell wall polysaccharides and sterols, both compounds being provided by inactive dry yeasts (IDY). These micelles contained a specific distribution of the initial sterols from the inactive yeasts. Above a concentration of 100 mg L(-1) in the rehydration medium, these micelles acted as emulsifiers. Their critical micellar concentration (cmc) was found to be about 4 g L(-1). During rehydration, purified micelles, at a concentration near the cmc, were able to interact quickly with yeast cell membranes by modifying the yeast plasma membrane order [monitored by steady-state fluorescence anisotropy of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene-p-toluenesulfonate (TMA-DPH) probe] and by increasing the sterol contents of ADY. Such an enrichment of ADY by very low concentrations of solubilized sterols was very efficient for the completion of fermentations. This is useful when musts are limited in available phytosterols or when micro-oxygenation is not desirable during fermentation.  相似文献   

Use of an avoidance test for the assessment of microbial degradation of PAHs     

Christine Lors  Sandrine Salmon 《Soil biology & biochemistry》2006,38(8):2199-2204

An avoidance test using the soil springtail Folsomia candida was used to assess changes in contamination levels at low doses of PAHs following incubation with indigenous microflora. A soil from a former coke site was diluted to 1% in an unpolluted soil from the same site, which was used as a control, then both substrates were remoistened to 80% field capacity. The diluted soil was previously shown to be strongly repellent to F. candida, although not toxic. After 2-month incubation at 20 °C, the mixture lost its repellence capacity and became attractive to the test animal, while the global 16 PAHs content had decreased to a great extent (50%). PAH disappearance was linked to the occurrence of indigenous microbiota able to degrade hydrocarbons.  相似文献   

Earthworm excreta (mucus and urine) affect the distribution of springtails in forest soils   总被引：1，自引：0，他引：1  

Sandrine Salmon 《Biology and Fertility of Soils》2001,34(5):304-310

The collembolan species Heteromurus nitidus, exclusively located in soils at pH>5, can be cultured in acidic humus. As this species is attracted to the excreta of earthworms from calcic mull, its distribution is supposed to be determined only indirectly by soil pH through the distribution of earthworms. Higher densities and biomasses of Lumbricidae were observed in a calcic mull (pH 7.8) than in an acidic mull (pH 4.8) and a moder humus (pH 4.2). Choice experiments were performed to compare the attraction of H. nitidus to the mucus-urine mix of five earthworm species from the calcic mull and the acidic mull. H. nitidus was attracted to the excreta of the five species, whatever their ecological category and the humus form from which they originated. The collembolan Heteromurus major, which was indifferent to soil pH, was not attracted to earthworm excreta, which emphasizes the significance of this phenomenon for the distribution of H. nitidus over a pH range. The attraction of H. nitidus to earthworm excreta tended to be weaker and more variable when earthworms originated from acidic mull compared to calcic mull, particularly in the case of Lumbricus terrestris. Increased earthworm density reinforced by better mucus quality and quantity could determine the distribution of H. nitidus according to soil acidity. The only urine compound capable of attracting H. nitidus was NH₃ at a low concentration (0.03 g l^-1). The NH₃ content of the mucus-urine mix which attracted H. nitidus was 0.037 g l^-1, and was therefore responsible, at least partly, for the attraction.  相似文献   

小熊猫源铜绿假单胞菌耐药性和耐药基因的研究     

邹洁建  古河祥  翟俊琼  萨家祺  陈武  杜雪晴 《野生动物学报》2021,(2):437-444

为了鉴定小熊猫(Ailurus fulgens)肺源致病菌并研究其耐药性和耐药基因,从死亡小熊猫肺部组织中无菌分离培养致病菌,进行革兰氏染色及16S rDNA测序鉴定。采用纸片扩散法(K-B法)进行细菌药敏试验和小鼠致病性试验,应用PCR法检测分离株的28种β-内酰胺酶相关基因、6种氨基糖苷类修饰酶基因(AMEs)、外膜蛋白D2基因(oprD2)、磺胺耐药基因(qacE△1-sul1)、3种整合子基因(intⅠ1、2、3)和主动外排泵调节基因(mexR)等共40种耐药基因。肺组织样品中分离培养的1株菌鉴定为铜绿假单胞菌,革兰氏染色阴性,药敏试验对氯霉素敏感,对β-内酰胺类、头孢类、氨基糖甙类、大环内酯类、硝基咪唑类、喹诺酮类和利福霉素等均具有耐药性,小鼠表现与小熊猫相似的症状而死亡。5种耐药基因TEM、aac(3)-Ⅱ、ant(3″)-Ⅰ、qacE△1-sul1、intⅠ1为阳性,其他35种为阴性。该小熊猫肺源铜绿假单胞菌具有较强的致病性和多药耐药性,其耐药机制与5种耐药基因有关。  相似文献   

Lymphocyte stimulation: selective destruction of cells during blastogenic response to transplantation antigens   总被引：8，自引：0，他引：8  

S E Salmon  R S Krakauer  W F Whitmore 《Science (New York, N.Y.)》1971,172(982):490-492

The blastogenic response of human lymphoid cells toward any individual's transplantation antigens can be deleted by the addition of tritiated thymidine of high specific activity during the incubation of the lymphoid cells in mixed leukocyte culture. After the immunocompetent clones which responded to histocompatibility antigens had been destroyed, the remaining population still retained its capacity to respond to unrelated antigens, including other transplantation antigens.  相似文献   

A PRELIMINARY NOTE ON SOIL MOISTURE AND TEMPERATURE FACTORS IN THE WINTER-KILLING OF GRAIN CROPS     

Salmon SC 《Science (New York, N.Y.)》1918,47(1207):173-174

  相似文献   

SA对水分胁迫下红小豆叶片过氧化物酶活性的影响   总被引：3，自引：0，他引：3  

杨剑平  金文林  徐红梅  王文平  陈莹玉 《北京农学院学报》2002,17(4):11-14

水杨酸(SA)处理红小豆叶片3d后,处理叶片及未接受处理叶片内的POD活性增加,并且不同浓度的SA对叶片内POD活性影响不同.通过测定渗透胁迫14d的红小豆植株叶片发现,SA处理能显著增加渗透胁迫下叶片中的POD活性.  相似文献   

Thermally Switchable Periodicities and Diffraction from Mesoscopically Ordered Materials     

JM Weissman  HB Sunkara  AS Tse  SA Asher 《Science (New York, N.Y.)》1996,274(5289):959-960

Two switchable, mesoscopically periodic materials were created by combining crystalline colloidal array (CCA) self-assembly with the temperature-induced volume phase transition of poly(N-isopropylacrylamide) (PNIPAM). Body-centered-cubic CCAs of hydrated, swollen PNIPAM particles Bragg-diffract infrared, visible, and ultraviolet light weakly, whereas arrays of compact shrunken particles diffract efficiently. A tunable diffracting array was also created by embedding a CCA of polystyrene spheres within a PNIPAM hydrogel that swells and contracts with temperature; thus the array lattice constant varies with temperature, and the diffracted wavelength was thermally tunable across the entire visible spectrum. These materials may find applications in many areas of optics and materials science.  相似文献   

不同耕作措施下秸秆还田对土壤速效养分和微生物量的影响   总被引：9，自引：2，他引：7  

李纯燕  杨恒山  萨如拉  张瑞富  曹倩  张丽娟 《水土保持学报》2017,31(1):197-201

为揭示西辽河平原玉米秸秆还田的效应,在2014—2015年设秸秆深翻还田(DR)和秸秆旋耕还田(RR)2个处理,以旋耕不还田(CK)为对照,研究了不同耕作措施下秸秆还田当年和次年对土壤速效养分和微生物量的影响。结果表明:DR和RR均能不同程度的提高土壤碱解氮、速效钾的含量和细菌、真菌、放线菌的数量,且DR较RR的效果更为明显,RR对土壤有效磷含量影响不大。秸秆还田次年完熟期,3个土层(0—10,10—20,20—30cm)的平均值,土壤碱解氮含量DR和RR分别较CK增加了26.60%,16.34%,有效磷含量分别增加了19.81%,0.92%,速效钾含量分别增加了23.95%,12.53%,3个土层的总计,细菌数量分别增加36.46%,9.80%,真菌数量分别增加了22.10%,21.90%,放线菌数量分别增加23.55%,17.38%。秸秆还田当年与次年相比,土壤速效养分除拔节期当年增长幅度低于次年外,其他各时期均表现为当年增长幅度高于次年,微生物量表现为次年增长幅度高于当年;秸秆还田与对照相比,土壤速效养分和微生物量的增加,主要表现在0—10cm土层;不同生育时期相比,土壤速效养分还田当年以完熟期最大,次年以拔节期最大。  相似文献   

山楂PCR-SSCP反应体系与反应条件的优化     

撒云俐  那冬晨 《农业科学与技术》2017,18(3)

[目的]优化山楂PCR-SSCP反应体系与反应条件.[方法]以山楂为研究材料,采用改良的CTAB法分步提取叶绿体DNA和核DNA.从8对候选引物中分别筛选适合对叶绿体DNA和核DNA进行PCR扩增的引物,同时进行PCR-SSCP反应体系和反应条件的优化.琼脂糖凝胶电泳检测PCR扩增产物,非变性聚丙烯酰胺凝胶电泳检测变性后的PCR扩增产物.[结果]筛选出ropB、ropL、rpoC1、ITS2和psbA-tmH五对引物适用于山楂的PCR-SSCP分析.电泳时,上样缓冲液(不含甘油)与PCR产物等量混合,98℃碱(1％NaOH)变性15min,采用6％的聚丙烯酰胺凝胶(交联度29∶1),电泳缓冲液0.5×TBE,在4℃恒温和200 V恒压的条件下,电泳3～4 h,可得到较好的山楂PCR-SSCP电泳图谱.[结论]建立了山楂PCR-SSCP最优反应体系与反应条件,为山楂SSCP分析奠定基础.  相似文献