Inhibition of glycosidases by Lepidoptera; roles in the insects and leads to novel compounds?

Summary Glycosidase inhibitors are widespread in plants and can be sequestered by Lepidoptera, for which they can presumably serve as defences by making the insects indigestible to a range of potential predators. As a result of this study of eight British species of moth and butterfly it was found that glycosidase inhibitors in the insects could then be detected in the larval food plants which were not previously known to contain them; however, some were only detectable in the plants after concentration. In some cases the inhibition of specific glycosidases by Lepidoptera was detected even though the insects had not apparently acquired them from their food plants. Inhibition of-N-acetylglucosaminidase was observed in most of the adult Lepidoptera analysed but further work is required to identify the inhibitors, though they are likely to be nitrogen-containing compounds. Weak anti-HIV activity was also observed in the glycosidase-inhibiting fractions ofAcherontia atropos and the plantUrtica dioica.     

高等水生植物对藻类生长的克制效应

本文综述了高等水生植物对藻类生长的克制效应的机理研究概况，及国内外最新的抑藻物质提取、分离、鉴定方法，并对其在水体畜养养化治理方面的应用前景作了进一步概述。     

硝化速率法用于活性污泥活性测试的研究

以城市污水厂回流污泥中的硝化细菌(氨氧化细菌和亚硝酸盐氧化细菌)为受试生物,HgCl2为标准毒性物质,通过对两组实验--氨氧化速率实验(NH 4-N→NO-2-N)和亚硝酸盐氧化速率实验(NO-2-N→NO-3-N)的研究表明,氨氧化细菌对HgCl2的灵敏度(IC50=0.034 mmol/L)明显高于亚硝酸盐氧化细菌(IC50=0.20 mmol/L).氨氧化速率法测试活性污泥活性时,使用NH 4-N或NO-X-N指标需要120 min或更长的时间,但使用NO-2-N指标仅需30 min就可完成测试,而且结果重现性要比NH 4-N和NO-X-N好,其变异系数CV为5.9 %.     

Effect of arsenic and mercury speciation on inhibition of respiration rate in activated sludge systems

The inhibition effect of arsenite, As(III), arsenate, As(V), inorganic mercury, Hg(II) and methylmercury, MeHg, on the respiration rate of activated heterotrophic sludge microorganisms was evaluated. As(III) and MeHg were much more toxic to activated sludge than As(V) and Hg(II) respectively. The effect of various experimental parameters on the toxicity, such as sludge age, concentration of suspended solids and exposure time, was investigated. An increase of sludge age or the concentration of suspended solids reduces the observed inhibition. Longer exposure seems to dramatically increase the inhibition of As(III), MeHg and Hg(II) during the first hours of exposure, while the later inhibition increases at a slower rate. On the contrary, in the presence of As(V), 24 hours after exposure, the respiration rate was similar to that of the control biomass.     

发酵稻草抑藻机理研究

稻草在通气条件下经1个月发酵后,发酵稻草及其发酵液对鱼腥藻和念珠藻的生长具有显著的抑制效果,而对小球藻的抑制效果不明显,这说明发酵稻草的抑藻作用是有特异性的;经过灭菌的发酵稻草、没有经过发酵的稻草则没有抑藻作用,显示抑制藻类的物质是在稻草经过发酵后形成的,且该物质对热敏感。我们从发酵稻草中分离出21株微生物,发现其中一株(B3)具有和发酵稻草相同的抑藻效果,它能强烈地抑制鱼腥藻和念珠藻的生长,但它的发酵滤液没有抑制作用。本实验表明发酵稻草的抑藻作用是由于稻草在发酵过程中富集了某种微生物,这种微生物直接作用于藻类,使藻类的生长受到抑制,甚至死亡。     

应用淡水发光菌研究二元重金属混合物的联合毒性

应用新型淡水发光菌一青海弧菌Q67(Vibrio qinghaiensis sp.nov-Q67)发光值的测定。对铜锌、铜汞、铜镉、铜镍等4种重金属混合物的联合毒性进行了评价。结果表明。铜锌混合物对Q67的联合毒性等于两者的毒性之和。作用方式表现为加和作用：铜汞、铜镉、铜镍3种混合物对Q67的联合毒性则表现为拮抗作用。     

氨氮对餐厨垃圾厌氧消化性能及微生物群落的影响

为探析氨氮（TAN）对餐厨垃圾厌氧消化性能及微生物群落的影响,在串联批次实验中引入氨氮胁迫,结合Miseq高通量测序分析,研究了不同TAN浓度下厌氧消化系统的过程参数响应以及微生物群落动态.结果显示,随TAN增加,甲烷回收率从（96.53±2.66）%下降至（63.13±0.73）%,消化时间从435h延长至915h,连续驯化下,TAN为3000mg/L的实验组产气性能完全恢复,而高氨氮实验组（TAN³6000mg/L）仍处于抑制状态.相较于乙酸代谢而言,长链挥发性脂肪酸（LCVFAs）代谢对TAN的耐受度更高（6000mg/L）,但一旦被抑制,其功能难以通过驯化恢复.从微生物层面上看,高丰度且功能冗余的水解酸化细菌保证了各TAN梯度下的水解酸化作用;氨氮敏感的Methanosaeta和Methanospirillum也能通过驯化被耐氨的Methanosarcina和Methanoculleus取代,从而维持系统产甲烷功能;相比之下,产氢产乙酸菌功能高度专一,仅C₄~C₁₈降解菌Syntrophomonas和丙酸降解菌Pelotomaculum被检测到,在连续的高氨氮暴露下,前者的丰度虽有一定程度的恢复,但后者未能被驯化,最终系统出现以丙酸为主的LCVFAs积累,产气性能恶化.可见, LCVFAs的互营降解才是氨抑制失稳的关键环节.     

不同小分子物质与传统抗菌剂对混合菌生物膜形成的抑制效应

针对污水处理系统混合菌形成的生物膜,比较了两种传统抗菌剂(银离子和氯)及3种小分子物质,包括双(3-氨基丙基)胺、(Z-)-4-溴-5-(溴乙烯)-2(5H)-呋喃酮(BBF)和香兰素对生物膜形成的抑制效应.结果表明,本研究所选用的传统抗菌剂中,0.05~10 mg·L-1Ag+对生物膜形成的抑制率为23%~70%,0.01~20 mg·L-1氯对生物膜形成的抑制率为23%~53%.而在3种小分子物质中,500~2000μmol·L-1双(3-氨基丙基)胺对生物膜形成的抑制率为16%~68%,0.1~200 mg·L-1香兰素对生物膜形成的抑制率为20%~37%,1~20 mg·L-1BBF对生物膜形成的抑制率为11%~18%.高浓度的Ag+(0.1~10 mg·L-1)会显著抑制混合菌的生长,且浓度越高,抑制效果越显著.1000μmol·L-1以下的双(3-氨基丙基)胺基本不会抑制混合菌的生长,但高浓度(2000μmol·L-1)的双(3-氨基丙基)胺会显著抑制混合菌的生长.     

游离亚硝酸抑制硝化杆菌属(Nitrobacter)活性动力学研究

为探究游离亚硝酸（FNA）对亚硝酸盐氧化细菌中硝化杆菌属（Nitrobacter）活性抑制动力学影响,采用序批式活性污泥（SBR）反应器,在通过改变系统进水FNA浓度达到富集Nitrobacter基础上,以富含Nitrobacter污泥为对象（宏基因组物种注释和丰度分析显示上Nitrobacter占细菌总数40.3%）,基于批次试验,考察不同FNA浓度梯度下亚硝酸盐氧化过程比亚硝态氮氧化速率（SNiOR）变化规律,进而拟合FNA抑制Nitrobacter活性抑制动力学模型,并进行统计学分析.结果表明,当FNA≤0.1mg/L时,随着FNA浓度升高,SNiOR迅速升高.当FNA>0.1mg/L时,SNiOR随着FNA浓度升高而降低.尤其当FNA浓度高于0.7mg/L时,SNiOR始终维持在0gN/（gVSS·d）,表明Nitrobacter活性统被完全抑制.统计学分析结果显示相对于Haldane、Aiba、Edwards-1#、Edwards-2#、Luong抑制动力学模型,Han-Levenspiel模型最适合描述FNA对Nitrobacter活性的抑制影响.其统计学常数：残差平方和（RSS）为0.02、可决系数（R²）为0.90、拟合方程的方差检验统计量F值为78.1、可信度P值为3.29×10^-12,其动力学常数值分别为：最大比亚硝态氮氧化速率（r_max）为1.57gN/（gVSS·d）;半饱和常数（K_S）为0.01mg/L;临界抑制常数（S_m）为0.66mg/L.     

Toxicity evaluation of ZnO and TiO2 nanomaterials in hydroponic red bean (Vigna angularis) plant: Physiology, biochemistry and kinetic transport

The toxicity and kinetic uptake potential of zinc oxide(Zn O) and titanium dioxide(TiO_2)nanomaterials into the red bean(Vigna angularis) plant were investigated. The results obtained revealed that Zn O, due to its high dissolution and strong binding capacity, readily accumulated in the root tissues and significantly inhibited the physiological activity of the plant. However, TiO_2 had a positive effect on plant physiology, resulting in promoted growth. The results of biochemical experiments implied that Zn O, through the generation of oxidative stress, significantly reduced the chlorophyll content, carotenoids and activity of stress-controlling enzymes. On the contrary, no negative biochemical impact was observed in plants treated with TiO_2. For the kinetic uptake and transport study, we designed two exposure systems in which Zn O and TiO_2 were exposed to red bean seedlings individually or in a mixture approach. The results showed that in single metal oxide treatments, the uptake and transport increased with increasing exposure period from one week to three weeks.However, in the metal oxide co-exposure treatment, due to complexation and competition among the particles, the uptake and transport were remarkably decreased. This suggested that the kinetic transport pattern of the metal oxide mixtures varied compared to those of its individual constituents.