高温堆肥中微生物的生长特征及动力学建模

对高温好氧堆肥中微生物的生长特征和动力学进行了研究，发现微生物的生长受温度影响很大，随温度变化呈波动性变化．同时，基于Logistic模型和Malthus模型，对微生物生长进行分析，得到了描述堆肥过程中的微生物生长动力学模型和模型参数．用实验数据与模型计算值进行验证比较，模型计算与实验结果拟合良好，模型正确地反映了高温好氧堆肥中微生物的生长过程及其动力学机制．图3表1参12     

Ag(I)对大肠杆菌抑制作用影响因素的分析

通过测定在各种条件下Ag(I)对大肠杆菌Escherichia coli的生长的抑制作用,系统分析了各参数对Ag(I)毒性的影响.结果表明:好氧、厌氧状态下,Ag(I)对E.coli的抑制能力基本相同;在LB培养基、氨基酸基本培养基和标准基本培养基中Ag(I)开始抑制E.coli生长的浓度差异较大,分别为10、0.5、0.1μmol/L; LB组分中的酵母粉的加入完全消除了Ag(I)对E.coli的抑制作用;此外,菌体浓度越高抑制其生长所需的Ag(I)浓度也越高.因此Ag(I)对E.coli生长的抑制作用与氧化应激无关,而与培养基种类、培养基组分及菌体浓度高度相关.     

Ag（Ⅰ）对大肠杆菌抑制作用影响因素的分析

通过测定在各种条件下Ag（Ⅰ）对大肠杆菌Escherichia coli的生长的抑制作用,系统分析了各参数对Ag（Ⅰ）毒性的影响。结果表明：好氧、厌氧状态下,Ag（Ⅰ）对E.coli的抑制能力基本相同;在LB培养基、氨基酸基本培养基和标准基本培养基中Ag（Ⅰ）开始抑制E.coli生长的浓度差异较大,分别为10、0.5、0.1μmol/L;LB组分中的酵母粉的加入完全消除了Ag（I）对E.coli的抑制作用;此外,菌体浓度越高抑制其生长所需的Ag（Ⅰ）浓度也越高。因此Ag（I）对E.coli生长的抑制作用与氧化应激无关,而与培养基种类、培养基组分及菌体浓度高度相关。     

Cu（Ⅱ）对海洋浮游植物生长影响的初步研究

选择赤潮异弯藻(Heterosigma akashiwo Hada)、三角褐指藻(Pheodactylum tricornutum Bohlin)、海洋原甲藻(Prorocentrum micans Ehrenber)、裸甲藻(Gymnodinim sp.)、亚心型扁藻(Platymonas subcordiforus)、旋链角毛藻(Chaetoceros curvisetus Cleve)、中肋骨条藻(Skeletonema costatum(Greville)Cleve)、青岛大扁藻(Platymonashelgolanidica)8种浮游植物,采用一次培养实验方法,研究了重金属Cu(Ⅱ)对海洋浮游植物生长的影响,并在Logistic生长模型的基础上结合Lorentz方程和GaussAmp方程,引入Cu(Ⅱ)浓度项,建立了Cu(Ⅱ)胁迫下海洋浮游植物生长动力学模型——Logistic-W模型,描述了Cu(Ⅱ)存在条件下海洋浮游植物的生长过程.结果表明,较高浓度Cu(Ⅱ)对8种浮游植物的生长普遍具有抑制作用,而较低浓度Cu(Ⅱ)则可促进旋链角毛藻、中肋骨条藻、青岛大扁藻的生长;Lorentz方程可以描述Cu(Ⅱ)浓度对浮游植物生长速率参数的影响,而GaussAmp方程可以描述Cu(Ⅱ)浓度对浮游植物生物量的影响;Cu(Ⅱ)胁迫下浮游植物的生长可用动力学方程Logistic-W描述,实验验证该模型合理,其拟合相关系数R2为0.817～0.993,平均为0.916.论文提出的生长模型可以预测不同浓度Cu(Ⅱ)胁迫下海洋浮游植物的生长情况,也可根据浮游植物的生长情况推测相应海区的Cu(Ⅱ)浓度.     

活性污泥动力学模型的建立及在完全混合式污泥系统中的应用

首先建立了微生物衰减系数和污泥浓度、底物浓度的函数关系式,带入Lawrence-McCarty第一方程式得到了Logistic方程形式的微生物生长方程式.在分析污泥泥龄和污泥停留时间关系基础上,引入Monod方程建立了活性污泥动力学模型,推导证明了Lawrence-McCarty方程式是模型静态条件下的表达形式.用建立的活性污泥动力学模型对完全混合式污泥系统进行了模拟,并分析了水力停留时间Hydraulic retention time(HRT)和污泥停留时间Sludge retention time(SRT)对完全混合式污泥系统的影响,表明模型能很好地对活性污泥系统的动态过程进行模拟.根据模型编程画出了污泥系统相关变量关于HRT和SRT变化的三维曲面图,通过编程将复杂模型看作一定输入输出的函数,使得模型更易于应用和推广.     

藻毒素降解菌CQ5对MC-LR粗提液的降解动力学

针对近年来采用微生物法降解水体中的微囊藻毒素(microcystins,MCs)这一研究热点问题,以本课题组前期从太湖芦苇荡底泥中筛出的耐硼赖氨酸芽孢杆菌CQ5(Lysinibacillus boronitolerans)为考察对象,研究微生物对MC-LR的降解动力学.分别采用Logistic生长方程和Monod动力学方程构建菌株CQ5细胞生长动力学模型和MC-LR降解动力学模型.结果表明,菌株CQ5在以MC-LR粗提液为碳、氮源的无机盐培养基中的生长曲线符合Logistic生长模型,其中菌株生长环境承载量K为1.306,菌株生长平均速率r为0.1685,无量纲参数a为1.688;该菌株在6 d内可使MC-LR的浓度由14.12μg·L~(-1)降至1.57μg·L~(-1),降解率达88.86%,其一级反应速率常数k为0.3698,半衰期t_(1/2)为1.88 d;该降解过程中MC-LR浓度、菌株细胞密度和MC-LR降解速率3者间的偶合关系符合低浓度下的Monod模型,其中υ_max/K_s为0.342;一级反应动力学方程式S=e~(2.648-0.3698t)和Monod模型方程式S=14.12e~(-0.342Nt)(N=1.08)均可模拟预测降解体系中的MC-LR浓度,二者的模拟结果高度一致.本文可为研究微生物降解MC-LR的机理和推动MC-LR降解菌的工程应用提供理论参考.     

亚抑菌浓度氟苯尼考作用下质粒pSD11对大肠杆菌适应性的影响

通过分析cfr阳性质粒pSD11对大肠杆菌的适应性影响,并测定氟苯尼考对携带质粒pSD11的大肠杆菌MG1655(Escherichia col MG1655)的最低筛选浓度(MSC),评价亚抑菌浓度氟苯尼考作用下多重耐药基因cfr在大肠杆菌中的持续存在和扩散传播的风险.通过电转化的方法将质粒pSD11导入模式菌E.coli MG1655中,获得耐药菌株E.coli MG1655/pSD11.通过测定生长曲线,比较无抗生素作用下耐药菌株E.coli MG1655/pSD11与同源敏感菌株E.coli MG1655的生长动力学参数,评价质粒pSD11对宿主菌适应性的影响.并通过比较分析不同亚抑菌浓度(0.031 25,0.062 5,0.125,0.25,0.5,1.0和2.0μg/mL)氟苯尼考作用下的生长速率,测定氟苯尼考对携带质粒pSD11的宿主菌最小筛选浓度(MSC).携带质粒pSD11的耐药菌E.coli MG1655/pSD11的延滞时间(2.853 3±0.031 8 h/λ)相对于同源敏感菌E.coli MG1655极显著延长(2.825 3±0.024 4 h/λ),且世代时间也显著延长(分别为:1.705 7±0.006 4 h/G和1.526 9±0.007 8 h/G).氟苯尼考对耐药菌E.coli MG1655/pSD11的MSC为0.042 5μg/mL约为相应敏感菌的MICsus的1/100.本研究表明携带cfr基因的质粒pSD11在无抗生素选择下对宿主菌有明显的适应性影响,但是在极低的氟苯尼考浓度的作用下存在选择优势,能够平衡适应性成本使宿主菌得到富集与传播,以期为对该质粒在环境中的传播风险评估及氟苯尼考的临床应用提供的参考.(图2表2参18)     

复杂环境条件下富勒烯的微生物毒性效应

考察了光照、腐殖酸(HA)、共存污染物对富勒烯胶体悬浮液(nC60)的微生物毒性影响.研究结果表明,黑暗条件下2 h内7 mg·L-1的nC60、3—20 mg·L-1的HA、1.2 mg·L-1的1,2,4,5-四氯苯(TeCB)单独及其联合体系对埃希氏大肠杆菌(E.coli)均不产生急性毒性;光照条件下nC60悬浮液能通过滤光效应对E.coli起到保护作用;虽然HA不同加入方式改变了nC60形貌,但是在对E.coli毒性效应上并无差异;TeCB会与光照产生协同毒性效应,但是相同条件下TeCB与nC60混合体系所表现出的抑菌效应与单纯nC60体系相当,即复合污染体系中nC60的存在遮蔽了TeCB对微生物的毒性作用.复杂环境条件下富勒烯并不一定表现出普遍认为的毒性效应,其滤光作用反而会在一定程度上保护微生物免受光照及其他有毒物质的毒性影响.     

4种中药单体对IncX4型质粒pSD11稳定性的影响

以携带多重耐药基因cfr的IncX4型质粒pSD11为试验材料，研究小檗碱、黄芩苷、芦荟大黄素、姜黄素4种中药单体对耐药质粒稳定性的影响，为中药单体消除病原菌耐药性提供理论依据.通过测定最小抑菌浓度（MIC）及药物作用下携带质粒pSD11的大肠杆菌的生长曲线和生长动力学参数，分析中药单体的抑菌效果.结合实时荧光定量PCR(RTPCR)及平板计数研究药物对质粒稳定性的影响，同时检测胞外乳酸脱氢酶和碱性磷酸酶的含量分析中药单体对细胞壁、细胞膜的影响.结果显示，小檗碱、黄芩苷、芦荟大黄素对大肠杆菌MG1655/pSD11(Escherichia coli MG1655/pSD11)的MIC均为1 280μg/mL，姜黄素> 160μg/mL.4种中药单体对E. coli MG1655/pSD11具有一定的抑菌效果，生长动力学参数结果表明1/2 MIC小檗碱和黄芩苷显著延长E. coli MG1655/pSD11的滞后期；1/2 MIC姜黄素和1/2、1/4MIC芦荟大黄素极显著降低E. coli MG1655/pSD11的最大生长速率、延长时代时间.经1/2和1/4 MIC的小檗碱和黄...     

磺胺类化合物对大肠杆菌突变QSAR预测模型初探

抗生素被广泛应用于医疗、农业和畜牧业等领域,但是长期滥用会促进细菌的突变作用。本文以大肠杆菌(E.coli)为受试生物,测定了10种磺胺类抗生素(SAs)单一暴露时对E.coli的突变效应,采用物化参数Ebinding(抗生素与其靶蛋白的相互作用能力)与突变效应参数lgRC0-2(最高可观测突变促进效应浓度)或lgRCmax(突变促进率最大值对应的浓度),建立了突变效应的QSAR模型,并采用雷达图进行验证。结果表明,lgRC0-2与Ebinding模型和lgRCmax与Ebinding、DMG(偶极矩)模型的拟合系数R2分别是0.888、0.873,即lgRC0-2或lgRCmax与Ebinding相关性均较好,可能由于磺胺类化合物(SAs)会作用于叶酸合成通路,影响嘌呤、嘧啶碱基的合成,从而对E.coli的突变具有促进效应,且雷达图验证表明,上述2个模型均具有良好的内部预测能力。本研究有望为抗生素使用带来的生态风险评价以及药物设计提供相关指导。     

杉木生长对南方涛动的可能响应

对杉木中心产区边缘杉木个体年轮生长规律进行了研究，分析了杉木年轮生长的特点，建立杉木个体年轮的时间模型，求算年轮指数，通过对２０多年来南方涛动指数第一、第二主分量与杉木人工林生长关系的研究，探讨南方涛动对杉木生长的可能影响，以南方涛动第一、第二主分量为自变量，建立杉木人工林年轮生长模型，模拟精度达９１．０５％，说明南方涛动对杉木人工林胸径生长可能存在一定影响（α＝０．０５）。     

经济增长与农业碳排放关系的实证研究

研究首先基于农业投入与生产视角的6个主要方面碳源,测算了1993-2008年我国农业生产活动所导致的碳排放量,分析发现我国农业碳排放总量和强度分别年均增长率为4.08%、2.38%,但环比增速总体上处于阶段性下降态势。化肥、农药、农膜、农用柴油、灌溉、翻耕等导致碳排放年均递增率分别为3.45%、4.65%、7.20%、4.77%、1.22%、0.38%。进一步综合运用协整理论及误差修正模型,实证我国经济增长与农业碳排放之间的关系。结果表明：我国经济增长与农业碳排放总强度,以及经济增长与化肥、农药、农膜、农用柴油、翻耕等5类碳源导致的碳排放强度之间存在协整关系,且人均GDP每增加1%,农业碳排放总强度与化肥、农药、农膜、农用柴油、翻耕等碳源的碳排放强度分别增加1.72%、1.61%、1.18%、0.40%、2.48%和1.31%。最后,据此提出相关政策建议。     

Growth and recruitment of the deep-sea urchin Echinus affinis

Large samples of the sea urchin Echinus affinis Mortensen were obtained from a time-series of Agassiz trawlings from a 2 200 m-deep permanent station (Station M), and at neighbouring positions, in the Rockall Trough (North-east Atlantic Ocean) over a period of 7 yr (1978 to 1985). Counts of growth zones visible in the skeletal elements of the test were used to age individuals. Various growth functions were fitted to counts from a full range of the sizes available. Functions giving a sigmoidal growth curve fit the early phase of growth better than the von Bertalanffy model, although the latter provided better fit amongst larger sizes. The fit of a robust and flexible model recently developed by Preece and Baines to describe the human growth curve overcame this limitation. Skeletal banding is thought to result from seasonally varying growth as a result of annually pulsed fallout of phyto-detrital food to the deep-sea floor. Early stages were found in only a few of a time series of samples obtained with a fine-meshed epibenthic sledge, suggesting that recruitment to the population from its annual breeding may only occasionally be successful. Postlarval growth was estimated from samples taken soon after presumed settlement and later in the year. The fitted growth curve showed good agreement to that obtained from annual banding, and corroborates an initially exponentially increasing growth rate. Postlarval survivorship was estimated, by means of computer simulation, from a sample that included postlarvae along with a range in juvenile size, to be about 10% amongst postlarvae after settlement and thereafter about 90% yr^-1. Adults are inferred to be up to about 28 yr old. A markedly uneven representation of ages in a large subsample of aged adults of even frequency in size is interpreted by means of simulations as probably reflecting multi-year cycles in recruitment success. The possible causes of a varying size structure amongst large samples of adults, which showed some spatial segregation in relation to the track of the trawl on the bottom at Station M, are discussed.     

Copper fractal growth during recycling from waste printed circuit boards by slurry electrolysis

• Copper fractal growth was observed during WPCBs recycling by slurry electrolysis. • Dendrites fractal growth could be controlled by additive during electrodeposition. • Additive was proved to be an effective way to refine the copper crystal. • These findings contribute to enrich the study of slurry electrolysis. Superfine copper particles could be directly prepared from waste printed circuit boards by slurry electrolysis. Meanwhile, copper fractal growth could be observed. To better understand this phenomenon, the factors that affect copper dendrites in a point-cathode system were discussed in detail. These results showed that the fractal degree of copper dendrites increased as the increase of applied voltage and the decrease of copper sulfate and gelatin concentrations. Sodium lauryl sulfate and hydrochloric acid concentrations could not significantly impact the fractal degree of copper dendrites, while gelatin concentration could. The minimum copper fractal dimension was 1.069 when gelatin and copper sulfate concentration was 120 mg/L and 0.1 mol/L, respectively with an applied voltage of 11 V. Moreover, the results diffusion-limited aggregation model demonstrated that particle translational speed, particle numbers and binding probability significantly affected copper dendrite patterns. The scanning electron microscopy results indicated that the three additives greatly affected the refinement of the copper crystal. These findings contribute to enrich the theoretical study on metals recovery from e-waste by slurry electrolysis.     

A hydrodynamic and water quality modeling study of spatial and temporal patterns of phytoplankton growth in a stratified lake with buoyant incoming flow

A three-dimensional hydrodynamic and water quality model was applied to Lake Paldang, a lake in South Korea that is stratified by incoming flows. The spatial and temporal patterns of phytoplankton growth in this lake were determined from the model. The model was calibrated and verified using data measured under different hydrological conditions. The model results were in reasonable agreement with the field measurements, in both the calibration and verification phases. The distributions of water quality and residence time in the lake and phytoplankton response to changes in nutrient loads were examined with the model, and the influence of the hydrodynamics on phytoplankton response was analyzed. The simulation results indicated that Lake Paldang is an essentially phosphorus-limited system, but that phytoplankton growth is limited by low water temperature and short residence time during the winter and the summer monsoon period, respectively. The results of sensitivity analyses also suggested that the hydrodynamics within the lake may have an indirect influence on phytoplankton responses to changes in the limiting nutrient loads, and that reducing phosphorus loading from Kyoungan Stream should be a high priority policy for controlling algal blooms during the pre- and post-monsoon periods. From this study, it was concluded that the three-dimensional water quality model incorporating hydrodynamic processes could successfully simulate phytoplankton response to changes in nutrient loads and that it could become a useful tool for identifying the essential factors determining phytoplankton growth and for developing the best management policy for algal blooms in Lake Paldang.     

Influence of soil-applied coal combustion by-products on growth and elemental composition of annual ryegrass

The total annual production of coal combustion by-products in the USA is expected to exceed 150 million Mg by the year 2000. Agricultural utilisation may offer a partial solution to disposal problems, but the benefits and risks associated with using these materials must be assessed. Four coal combustion by-products, bed ash (BA) and fly ash (FA) from a fluidised-bed combustion furnace and stabilised scrubber sludge (SS) and a high gypsum content by-product (G) from flue gas desulphurisation processes were added to two soils at rates of 0, 20, 40 and 80 g kg-1. The growth and elemental composition of Gulf annual ryegrass (Lolium multiflorum L.) were evaluated in the treated soils. Adding FA, SS and G to both soils at application rates of up to 80 g kg-1 was not detrimental to the growth of ryegrass and resulted in higher yields than controls in some instances. Adding BA created a high alkalinity, high soluble-salt environment that initially inhibited seedling germination and significantly reduced (p<0.05) yields of dry matter, so it will probably need to be restricted to rates of lime requirement. Ryegrass concentrations of Cu, Zn, Ni, Pb, Cd and Cr were similar in control and treated soils, but levels of B, Se, As and Mo were raised in treatments. Based on low trace-element concentrations in ryegrass shoots and in soil solution, Se from FA application may be the only potential food-chain risk associated with application of the four coal combustion by-products used in this investigation.     

A model for measuring leaf growth rate of vegetative shoot in the seagrass, Zostera marina

A new model for determining leaf growth in vegetative shoots of the seagrass Zostera marina (eelgrass) is described. This model requires the weights of individual mature and immature whole leaves and leaf plastochrone interval (P_L) as parameters, differing from the conventional leaf marking technique (CLM) that requires cutting and separation between new and old tissue of leaves. The techniques required for the model are the same as for the plastochrone method, but the parameters differ between both methods in use of the weight of individual immature leaves. In a mesocosm study, eelgrass growth was examined, and parameters for the new model and plastochrone method (the weights of individual mature and immature leaves and P_L) were measured. Leaf growth rate was measured using the CLM and determined by the new method and the plastochrone method. The results were then compared between the CLM, the new model, and the plastochrone method. The results obtained with the new model were similar to those obtained with the CLM. However, the results of the plastochrone method differed from those of the CLM, while the weight of immature leaves varied seasonally. The new model was also used to determine leaf growth in a natural eelgrass bed in Mikawa Bay, Japan, and revealed the growth rates in all shoots and those of different ages. This method would be advantageous as an accurate means of direct measurement in fieldwork, and should therefore be a useful tool for monitoring seagrass growth.     

Interrelation of Cd‐lon concentrations and the growth and activities of microorganisms in two growth media†

Partitioning of native or anthropogenic heavy metals in solid and solution phases of soil is a result of network of several physico‐chemical reactions. The attainment of equilibrium between two phases is also regulated by biochemical processes. For practical purposes, the bioavailability of metal present in soil is predominantly regulated by the soil solution phase which is in dynamic equilibrium with the solid phase. The results of a model laboratory and greenhouse growth experiments have been used to investigate the effect of Cd‐ion concentrations (either in soil solution or in nutrient solution) on the growth and activities of microorganisms. The soil solution has been simulated by preparing a suspension of soil with 0.1 M NaNO₃ (1: 2.5) equilibrated for two hours. Important conclusions are as follows:

Increase in Cd‐ion concentration in soil solution or in nutrient solution induces corresponding adverse effect on the growth and activities of microorganisms. Thus, it seems that Cd‐ion concentration is a more sensitive indicator for assessing the effect of metal pollution upon the growth and activities of soil microorganisms in comparison to total Cd contents.

During active microbial growth phase, a large part of the organically bound Cd was released in the soil solution which is largely bioavailable. This process is termed as mobilisation. There was momentary increase of Cd‐ion concentration in soil solution which intoxicated the growing organisms. After this stage, the Cd ions from the solution phase were removed by the newly formed solid phase (nonviable biomass) and were transformed in non‐available form. This process is termed as immobilisation.

The consequences and importance of these results for practical agriculture and in deciding the limits or guidelines on the maximum tolerable metal load in soils are discussed.