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991.
莠去津降解菌HB-5的最佳产酶培养基及发酵条件 总被引:2,自引:0,他引:2
从农药厂废水中分离到一株降解莠去滓的节杆菌(Arthrobacter sp.)HB-5,以从该菌中提取到的降解酶对莠去津的降解率为指标,进行最佳产酶培养基及发酵条件的优化研究,对其产酶量进行了评价.通过正交试验和均匀试验,对细菌HB-5的发酵培养基进行了优化研究.运用SAS软件进行结果分析,所获优化培养基配方为:蔗糖3.0g·L-1,莠去津0.38g·L-1,K2HPO40.5g·L-1,KH2PO41.2 g·L-1,MgSO4·7H2O 1.2g·L-1,NaCl 0.1g·L-1,微量元素溶液3.8mL·L-1.得到菌株培养的最佳优化条件为:菌株发酵液培养时间为48h.接种量为2%,发酵液初始pH值为9,250mL三角瓶中装液量为80mL经优化后,降解酶对莠去津的降解率(91.64%)比原培养基(40.67%)提高了125%. 相似文献
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993.
Residues of organochlorine pesticides in surface soils from college school yards
in Beijing, China 总被引:1,自引:0,他引:1
Organochlorine pesticides (OCPs) have been a major environmental issue, attracting much scientific concern because of their nature of toxicity, persistence, and endocrine disrupting effects. Soil samples were collected from ten college school yards in Beijing in 2006 and analyzed to determine fifteen OCPs. Dichlorodiphenyltrichloroethanes (DDTs) were found to be the main pollutants, accounting for 93.70% of total OCPs, followed by hexachlorohexanes (HCHs) (2.25%) and hexachlorobenzene (HCB) (1.82%). Content... 相似文献
994.
Assessment of locomotion behavioral defects induced by acute toxicity from
heavy metal exposure in nematode Caenorhabditis elegans 总被引:1,自引:1,他引:0
Locomotion behaviors are susceptible to disruption by a broad spectrum of chemicals and environmental stresses. However, no systematic testing of locomotion behavior defects induced by metal exposure has been conducted in the model organism of nematode Caenorhabditis elegans. In this study, the acute toxicity from heavy metal exposure on the locomotion behaviors was analyzed in nematodes. Endpoints of head thrash, body bend, forward turn, backward turn, and Omega/U turn were chosen to evaluate the locomotio... 相似文献
995.
水体的营养水平对苦草(Vallisneria atans)生长的影响 总被引:3,自引:2,他引:1
在室外控制条件下,以太湖梅梁湾水体现状营养水平(ρ(TN)为5 mg/L和ρ(TP)为0.2 mg/L)为依据,研究营养盐含量升高对苦草生长的影响.结果表明:①在满足光补偿点及无种间竞争等的条件下,苦草在营养水平为ρ(TN)>10 mg/L和ρ(TP)>0.4 mg/L的水中也能成活.②随着营养盐含量的升高,苦草生物量的增长率逐渐降低,当水中ρ(TN)达到10 mg/L和ρ(TP)达到0.4 mg/L时,苦草的生物量开始减少;营养盐含量升高对苦草叶片特征的影响不明显,而苦草根状茎的生物量却随着营养盐含量的升高而逐渐减少,当水体营养水平达到ρ(TN)为10 mg/L和ρ(TP)为0.4 mg/L时,除叶片长度外,苦草的其他形态指标值均显著下降.③在梅梁湾水体现状营养水平的基础上,当水中磷含量增加1倍时对苦草生长造成的抑制作用大于氮含量增加1倍时;当二者均增加时,对植物生长造成的抑制作用显著增加. 相似文献
996.
Microbial reduction of As(V) (i.e., arsenate) plays an important role in arsenic (As) mobilization in aqueous environment. In this study, we investigated As(Ⅴ) reduction characteristics of the bacteria enriched from the arsenic-contaminated soil at an abandoned smelter site. It was found that As(Ⅴ) was completely reduced to As(Ⅲ) (i.e., arsenite) in 21 h. After 3-d incubation, a yellow solid was precipitated and the concentration of As(Ⅲ) decreased sharply. After 150 h incubation, ca. 65% of soluble arsenic was removed from the solution. The analysis of the precipitate by scanning electron microscopy and energy dispersive spectrometer (SEM-EDS) and X-ray diffraction (XRD) revealed that the main component was crystalline arsenic sulfide (ASS). Microbial mediated reduction and mobilization of adsorbed As(Ⅴ) on ferric hydroxide was also examined. In the microcosm slurry experiment, ca. 53% of the adsorbed As(V) was reduced to As(Ⅲ) by the bacteria, which resulted in an appreciable release of arsenic into aqueous phase. The released arsenic was present predominantly as As(Ⅲ). The microbial diversity was analyzed by 16S rDNA-dependent molecular phylogeny. A near-full-length 16S rDNA gene clone library was constructed. The 197 clones were analyzed using RFLP (restriction fragment length polymorphism) and 72 OTUs were obtained, which contributed 51% of the content for total clone number in six OTUs. Six bacterial clones in these six OTUs were selected for sequencing and the sequenced clones were found to belong to the group Caloramator, Clostridium, and Bacillus. 相似文献
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