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细胞衰减是微生物内源过程的一个重要组成部分,可分为由细胞死亡引起的数量衰减和由细胞活性降低引起的活性衰减两部分.通过挥发性脂肪酸(VFA)吸收速率(VFAUR)测定、荧光原位杂交技术(FISH)以及LIVE/DEAD细胞染色技术,研究了富集聚糖原菌(GAOs)在序批式反应器(SBR)系统中好氧环境下的衰减特征.结果表明,当T=30℃、进料中m(COD)∶m(P)=100时,SBR系统中GAOs富集比例达94%.测定和计算表明,SBR富集系统中GAOs衰减速率和死亡速率分别为0.132 d-1和0.034 d-1,其数量衰减和活性衰减占其细胞总衰减比例分别为26%和74%.可见,GAOs数量衰减只占其细胞总衰减中很小一部分,而绝大部分衰减由活性衰减所引起. 相似文献
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通过常规耗氧速率(OUR)测定方法、荧光原位杂交技术(FISH)和LIVE/DEAD细胞活性实验,分别研究了序批式反应器(SBR)硝化系统和生物营养物去除(BNR)系统中硝化细菌的好氧衰减特征.实验结果表明,SBR硝化系统中硝化细菌在衰减过程中由细胞死亡引起的衰减分别占细胞总衰减的33%(SRT=10 d)和50%(SRT=40 d);相应地,由活性降低引起的衰减分别占细胞总衰减的67%(SRT=10 d)和50%(SRT=40 d).长SRT可能会选择出能够更好地适应饥饿状态的硝化菌种,使细菌能够迅速地做出紧迫反应,从而降低其衰减速率.在BNR系统中(SRT=15 d),硝化细菌在衰减过程中由细胞死亡引起的衰减约占细胞总衰减的45%,由活性降低引起的衰减约占细胞总衰减的55%.两种系统中硝化细菌由细胞死亡引起的衰减比例不同是由于两种系统中不同微生物组成所致. 相似文献
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进水C/N对富集聚磷菌的SNDPR系统脱氮除磷的影响 总被引:1,自引:0,他引:1
为了解富集聚磷菌(PAOs)的同步硝化反硝化除磷(SNDPR)系统的脱氮除磷特性,采用延时厌氧(180min)/低氧(溶解氧0.5~1.0mg/L)运行的SBR反应器,以实际生活污水为处理对象, 通过投加固态乙酸钠调节进水C/N值(约为11,8,4,3),考察其对系统脱氮除磷特性及同步硝化反硝化(SND)脱氮率的影响.结果表明:C/N对系统的除磷性能没有影响,出水PO43--P浓度均稳定在0.3mg/L左右,这是由于系统内聚磷菌(PAOs)含量高,且在低氧段可同时发生好氧吸磷与反硝化吸磷.随着C/N的增大,出水NH4+-N浓度升高,C/N下降时,出水NO3--N浓度升高.此外,随着C/N的减小,厌氧段反硝化所消耗的COD占进水COD的比例增大,SND可利用的内碳源-PHAs储存量减少,但PHV的利用率增加;当C/N为4~8时,SND现象最明显,SND脱氮率达50.8%,而其它C/N条件下,SND脱氮率都有相应程度的减弱.C/N为8时,系统出水综合指标最好,TN去除率高达80.8%. 相似文献
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C/P对EBPR系统PAOs与GAOs竞争及PHAs代谢过程影响研究 总被引:2,自引:0,他引:2
以富含聚磷菌(PAOs)活性污泥为基础,基于FISH技术研究了SBR工艺不同C/P(25∶1、20∶1、15∶1和10∶1)对EBPR系统中功能菌变化特征与微生物胞内聚合物(PHAs)代谢过程的影响.结果表明,经过10 d运行处理,C/P分别为25∶1、20∶1和15∶1系统磷酸盐去除率88%,而C/P为10∶1系统磷酸盐的去除率为0%.FISH检测结果显示,随着C/P从25∶1下降到10∶1,EBPR系统中PAOs的含量相应从(76.42±1.24)%减少到(10.40±0.97)%,而聚糖菌(GAOs)则从(16.36±3.41)%增加到(34.25±2.59)%.在厌氧段,不同C/P条件下EBPR系统中PHB和PHV的合成动力学系数大小分别为K25∶1K20∶1K15∶1K10∶1和K15∶1K20∶1K25∶1K10∶1.随着C/P从25∶1下降到10∶1,合成PHB在PHAs中所占的比例从85%下降到24%,而PHV则从15%上升到76%;在好氧段,不同C/P系统消耗PHB和PHV的动力学系数大小均为K20∶1K25∶1K15∶1K10∶1,且C/P为25∶1、20∶1和15∶1时系统消耗主要成分是PHB(占PHAs 71%~75%),而C/P为10∶1时系统消耗主要成分是PHV(占PHAs 71%).由此表明,随着C/P的降低,EBPR系统内GAOs增加而PAOs减少,从而导致系统内PHB合成与消耗比例逐渐减少,而PHV合成与消耗比例逐渐增加. 相似文献
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Fetal cells were enriched from maternal blood using density gradient centrifugation of Histopaque followed by magnetic-activated cell sorting (MACS) to select CD71-positive cells. For each specimen, cells partially purified by Histopaque were split into equal portions, and each portion was subjected to purification by MACS in parallel. Cells before and after MACS were subjected to dual-color fluorescence in situ hybridization (FISH) analysis with X- and Y-chromosome-specific probes. We found that the hybridization rates were decreased by approximately 10% after MACS based on duplicated analysis for each sample. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Stanislawa Weremowicz Deborah J. Sandstrom Cynthia C. Morton Catherine A. Niedzwiecki Mary McH. Sandstrom Frederick R. Bieber 《黑龙江环境通报》2001,21(4):262-269
Fluorescence in situ hybridization (FISH) was performed with probes specific for chromosomes 13, 18, 21, X and Y on 911 of 11123 (8.2%) amniotic fluid samples submitted to the present authors' laboratory for cytogenetic analysis over an 8-year period. Altogether 3516 hybridizations were performed with an interpretable FISH result on all chromosomes requested in 884/911 (97%) of cases. An uninformative FISH result occurred in 44 hybridizations among 27 cases (3%). Of a total of 89 karyotypically proven cases with aneuploidy that might have been detected by FISH, the overall detection rate was 84%. An inconclusive or incomplete FISH result occurred in 9/89 (10%) of these proven aneuploid cases. In the remaining 80 informative proven aneuploid cases, correct detection of aneuploidy was accomplished in 75/80 (94%) of samples. A false-negative result occurred in the remaining 5/80 (6%) of such informative cases. Eighteen cases had karyotypically proven abnormalities that could not have been detected by the targeted FISH. Aside from these 18 cases, FISH allowed correct detection of normal disomy in 785/804 (98%) of such cases. An incomplete FISH result occurred in 18 normal disomic cases. There was a single possible ‘false-positive’ FISH result for chromosome 21. Interphase FISH analysis of uncultured amniotic fluid cells has been shown to be a useful laboratory tool for rapid fetal aneuploidy screening during pregnancy. As with all clinical laboratory diagnostic tests, incomplete or inconclusive results (or even interpretive errors) occur in a small percentage of cases. Nevertheless, FISH results accompanied by other data and by appropriate counseling provide clinicians and patients with valuable information for clinical decision-making surrounding family planning and pregnancy management. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献