SRB固态发酵条件优选及动力学方程建立

为解决利用微生物法处理酸性矿山废水中菌种扩大培养、菌种保存和接种等问题,研究利用固态发酵法制备硫酸盐还原菌(SRB)固定化产品。实验以亚硫酸盐还原酶(SiR)作为菌种活性检测指标,进行生物质粒径、初始含水率、接种量单因素实验,响应面法确定各生物质载体固态发酵的最优条件并验证;用固载产品处理模拟酸性矿山废水数据按照Lineweaver-Burk作图法,建立SRB菌去除SO2-4的反应动力学方程。结果表明,以玉米芯为载体最佳发酵条件为:粒径8~20目、含水率70%、接种量10%,优化后SiR酶活为2.7385 U/g;木屑:粒径1~8目、含水率80%、接种5%,优化后SiR酶活为2.4863 U/g;甘蔗渣:8~20目、含水率75%、接种10%,优化后SiR酶活为4.2960 U/g。固载产品处理模拟酸性矿井水SO2-4,以1/v对1/[s]作图,玉米芯固载SRB菌的图相关性最好y=1176.9x+0.6034,R2=0.9199,建立玉米芯固载SRB菌的处理SO2-4动力学方程为V=1.657[s]/(1950.45+[s])。     

黑曲霉固态发酵三七渣产淀粉酶的研究

以三七渣为基质,采用黑曲霉固态发酵产淀粉酶,考察了硫酸铵(氮源)添加量、三七渣粒径、固体培养基含水率、发酵温度、发酵时间、菌悬液接种量等因素对产淀粉酶效果的影响,并采用正交实验对发酵条件进行了优化。单因子实验结果表明,黑曲霉固态发酵三七渣产淀粉酶适宜的硫酸铵添加量为40～60mg/g(以干药渣计),最佳三七渣粒径为100目,最适固体培养基含水率为55%,最佳发酵温度为34℃,最适发酵时间为7d,最佳菌悬液接种量为10%(质量分数)。正交实验多重比较的结果表明,优化的发酵条件为:硫酸铵添加量50mg/g,发酵温度34℃,发酵时间5d,在此发酵条件下,黑曲霉固态发酵三七渣产生的淀粉酶的酶活可达84.15U/g(以湿物料计)。     

固定化嗜麦芽寡养单胞菌的制备及其降解羽毛废弃物的初步研究

以自制壳聚糖小球为载体,采用吸附固定法制备固定化嗜麦芽寡养单胞菌(Stenotrophomonas maltophilia DHHJ),并将其用于羽毛废弃物降解。结果表明,采用3.0%(质量分数)的壳聚糖制成的壳聚糖小球的形态较好,经高压灭菌后弹性增加,呈多孔状,有很强的吸水性,有利于细菌的吸附固定和生长;在细胞稀释液中加入10%(质量分数)的壳聚糖小球,固定时间设为2d时,制得的固定化小球在发酵过程中释放的有效活菌数最多,可达7.0×106 cfu/mL;在连续10次、共计40d的序批发酵降解过程中,固定化菌的羽毛降解率和发酵液中的角蛋白酶酶活均保持在最大值的80%以上。固定化菌的发酵稳定性较强,能在较长时间内稳定、有效地降解羽毛,具有连续发酵潜力;固定化菌发酵降解羽毛的最佳工艺条件为:小球投加量50mg/mL,羽毛投加量25mg/mL,摇床转速130r/min,发酵5d。     

嗜麦芽寡养单胞菌DHHJ固态发酵羽毛工艺的研究

为了将微生物处理羽毛工艺产业化,利用课题组筛选得到的嗜麦芽寡养单胞菌,在液态发酵羽毛工艺的基础上进行固态发酵工艺的研究。通过发酵条件和培养基成分的优化,确定了嗜麦芽寡养单胞菌固态发酵羽毛的工艺为:初始pH为7.5,培养温度为35℃,培养时间为4 d,培养基组成是麸皮和干酪素,固液比是1∶1.5,照此工艺发酵,发酵液中蛋白质含量为23.78 mg/mL,角蛋白酶活为20.46 U/mL,菌株的产酶能力及降解羽毛能力显著高于液态发酵条件。     

三七渣固态发酵生产绿色木霉的工艺条件研究

考察了发酵时间、孢子液接种量、固态发酵培养基装料量、培养温度、光照条件等对三七渣固态发酵生产绿色木霉的影响,并采用正交实验优化了发酵工艺条件。结果表明,发酵过程受工艺条件的影响较大,孢子液接种量、固态发酵培养基装料量、发酵时间3个因素的交互作用极显著(p0.01),这3个因素以及它们之间的交互作用对实验结果的影响程度排序为:交互作用固态发酵培养基装料量孢子液接种量发酵时间;在最佳的发酵工艺条件(即培养温度24℃、无光照、接种量20%(1g三七渣接种2mL绿色木霉孢子液)、固态发酵培养基装料量12.5g、发酵时间8d)下,平均产孢量可达10.10×109 cfu/g。     

新型固定化硝化菌活性填料硝化活性的影响因素

以新型固定化硝化菌活性填料为研究对象,以游离态硝化菌为参照,分别考察了各个环境因素对固定化硝化菌硝化活性的影响,确定了最佳操作点为温度30℃,p H 8.0~9.0,DO 4.0 mg/L。与游离态硝化菌相比较,硝化菌固定化后并没有改变其对温度的敏感程度;固定化硝化菌可在偏碱性环境下保持较高的硝化活性;DO对固定化硝化菌的硝化活性有较大影响,需要较高的DO值来保持较高的硝化速率。为考察固定化硝化菌活性填料连续处理氨氮废水的效果,采用最佳操作点进行了连续运行实验,实验共进行60 d。结果表明,新型固定化硝化菌活性填料抗冲击负荷能力强,硝化性能高效稳定,实验条件下最高硝化速率可达到86.45 mg/(L·h)。     

玉米浸泡液制备苏云金杆菌生物杀虫剂的影响因素研究

以玉米淀粉生产过程中的浸泡液为培养基,摇瓶发酵培养苏云金杆菌生物杀虫剂,通过一系列单因子试验,考察了不同培养条件(种子液的种龄、接种量、浸泡液的含固率、初始pH值、摇床转速、发酵温度及发酵时间)对苏云金杆菌在玉米浸泡液中的生长(菌数增长与芽孢形成)以及发酵液的生物毒效的影响.研究表明,在最佳摇瓶培养条件(种子液种龄10 h,接种量2%,浸泡液含固量3%,初始pH值7.0～7.5,摇床转速200 r/min,发酵温度30℃)下发酵48 h,活菌数和活芽孢数分别可达到7.9×108 CFU/mL和5.5×108 CFU/mL,毒力效价为698.0 IU/μL.本试验可为生物农药的工业化生产提供实用参数.     

凤眼莲-固定化氮循环细菌联合作用对富营养化水体原位修复的研究

应用生态工程技术和原理,在夏季利用凤眼莲（Eichhornia crassipes Mart.）结合固定化氮循环菌对富营养化水体进行原位修复研究。试验结果表明,凤眼莲+固定化氮循环细菌联合作用和单独的凤眼莲处理对富营养化水体总氮和铵态氮去除之间存在显著的差异,凤眼莲+固定化氮循环细菌联合作用对富营养化水体中总氮和铵态氮的去除率分别达77.2%和49.2%;而凤眼莲处理则分别达73.7%和32.3%;但两者对富营养化水体中硝态氮的去除没有显著差异。接种固定化氮循环微生物有利于水体中Chla、COD_Mn的降低和水体透明度的提高,但两者没有明显的差异。当凤眼莲处理系统接种固定化氮循环细菌时,除了氨化细菌变化不明显外,亚硝化菌,硝化菌,反硝化菌群数量比单独凤眼莲处理系统增加1～1.5个数量级,且接种固定化氮循环细菌还有利于凤眼莲生物量及其体内氮积累量的增加。     

真菌漆酶在树脂D380上的固定及固定化漆酶的性质

为寻求一种廉价高效的漆酶固定化方法,以树脂D380为载体、戊二醛为交联剂,结合吸附法和交联法固定真菌漆酶,并研究固定化漆酶的性质。最优固定化条件：1g载体在20mL0．7％的戊二醛溶液中交联2h后,加入2mL稀释酶液和5mLpH为4的醋酸一醋酸钠缓冲溶液,在25℃下吸附反应6h,最终获得的酶活回收率为65．94％。固定化漆酶的最适温度为20℃,最适pH为4,在4℃下保存14d仍保持约80％的酶活力。自由漆酶和固定化漆酶的Km值分别为1．207mmol／L和1．616mmol／L,说明固定后漆酶对底物的亲和力有所下降。     

黄姜纤维素渣固态发酵生产蛋白饲料

利用酵母菌和黑曲霉对黄姜纤维素渣进行固态发酵生产蛋白饲料。研究了接种量、温度、固液比、发酵时间和通风量对发酵的影响。同时在单菌种发酵的基础上,对酵母菌和黑曲霉的混合发酵进行了初步探索,研究结果表明,混菌发酵的实验效果比单菌发酵的效果好。当条件为:黄姜纤维素渣25 g,加入脲0.53 g,KH2PO40.05 g,K2HPO40.05 g,Mg-SO40.05 g,NaCl 0.05 g,CaCl20.01 g,接种量为14%,温度30℃,固液比2∶1,发酵产物的蛋白质量分数可达到13.98%。     

Chloroaromatic pollutants in mussels incubated in two finnish watercourses polluted by industry

Concentrations of different chlorinated compounds were measured in mussels incubated in two polluted watercourses, a river (the River Kymijoki) and a lake (Lake Vanaja) for four weeks in summer 1995. The sum concentrations of polychlorinated phenols (PCP) and biphenyls (PCB) were both about 1 μg/g lipid weight (lw) in Lake Vanaja mussels, while in the River Kymijoki mussels PCPs were non-detectable and PCBs were measured 120 ng/g lIw. The concentrations of toxic polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners ranged between <17 and 370 pg/g Iw in Lake Vanaja mussels and between <38 and 11,000 pg/g lw in the River Kymijoki mussels. Polychlorinated diphenyl ethers (PCDE) were detected in the mussels incubated in the River Kymijoki (0.4–1.1 ng/g Iw), but not in those incubated in Lake Vanaja. Polychlorinated phenoxyanisoles (PCPA) were measured 33 ng/g lw and polychlorinated phenoxyphenols (PCPP) 300 ng/g lw in the mussels incubated in the River Kymijoki. PCPAs were also detected in reference samples, which were sediment and pike from the River Kymijoki and Baltic salmon, seal and white-tailed sea eagle.     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

Book review

The Pesticide Manual ‐ A World Compendium, 8th Edition, C.R. Worthing, Editor and S.B. Walker, Assistant Editor, British Crop Protection Council, BCPC Publications Sales, Bear Farm, Binfield, Bracknell, Berkshire RG12 5QE, England. 1987, 1100 pp., UK £50; Overseas £56. ISBN 0–948404–01–9.     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.     

Organochlorine compounds in a three-step terrestrial food chain

The concentrations of 15 organochlorine chemicals (PCBs and pesticides) were studied in a Central European oak wood food chain system: Great tit (Parus major), caterpillars (Tortrix viridana, Operophtera brumata, Erannis defoliaria), and oak-leaves (Quercus robur). Juvenile tits receive organochlorines from the mother via egg transfer and, eventually to a greater extent, from the caterpillar food source during nestling period. The concentrations of PCB 153 (2,2′,4,4′,5,5′-hexachlorobiphenyl, the most abundant in this study) was found in leaf material at ca. 1 ng/g, in caterpillars 10 ng/g, and in bird eggs 170 ng/g on an average and on a dry mass basis.     

The chemical stability of formulations of some hydrolyzable insecticides in aqueous mixtures with hydrolysis catalysts

Abstract

The active ingredients in commercial formulations of malathion, oxamyl, carbaryl, diazinon, and chlorpyrifos diluted to “spray tank”; concentrations with buffered distilled or natural water of pH 4–9 were stable for at least 24 hr. Formulations of trichlorfon were not stable at pH 7 or above but disappearance rates were slower than for the pure chemical in homogeneous solution. Cupric ion was observed to be an effective catalyst for the hydrolysis of a variety of pure organophosphorus insecticides but did not catalyze hydrolysis of the active ingredients of the formulations examined. Increasing the dilution of the formulation increased the susceptibility of malathion, oxamyl, and carbaryl to hydrolysis.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

Teratological effects of pesticides in vertebrates: a review

Abstract

In the last decades, the use and misuse of pesticides in the agriculture have increased, having a severe impact on ecosystems and their fauna. Although the various effects of pesticides on biodiversity have been already documented in several studies, to our knowledge no consistent overview of the impact of pesticides in vertebrates, both terrestrial and aquatic, is available. In this review, we try to present a concise compilation of the teratogenic effects of pesticides on the different classes of vertebrates – mammals, birds, reptiles, amphibians and fish.     

Radionuclides in pinon pine (Pinus edulis) nuts from los alamos national laboratory lands and the dose from consumption

Abstract

One of the dominant tree species growing within and around the eastern portion of Los Alamos National Laboratory (LANL), Los Alamos, NM, lands is the pinon pine (Pinus edulis). Pinon pine is used for firewood, fence posts, and building materials and is a source of nuts for food—the seeds are consumed by a wide variety of animals and are also gathered by people in the area and eaten raw or roasted. This study investigated the (1) concentration of ³H, ¹³⁷Cs, ⁹⁰Sr, ^totU, ²³⁸Pu, ^{239, 240}Pu, and²⁴¹ Am in soils (0‐ to 12‐in. [31 cm] depth underneath the tree), pinon pine shoots (PPS), and pinon pine nuts (PPN) collected from LANL lands and regional background (BG) locations, (2) committed effective dose equivalent (CEDE) from the ingestion of nuts, and (3) soil to PPS to PPN concentration ratios (CRs). Most radionuclides, with the exception of ³H in soils, were not significantly higher (p < 0.10) in soils, PPS, and PPN collected from LANL as compared to BG locations, and concentrations of most radionuclides in PPN from LANL have decreased over time. The maximum net CEDE (the CEDE plus two sigma minus BG) at the most conservative ingestion rate (10 lb [4.5 kg]) was 0.0018 mrem (0.018 μSv); this is far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem (1000 μSv). Soil‐to‐nut CRs for most radionuclides were within the range of default values in the literature for common fruits and vegetables.     

Degradation and sorption of imidacloprid in dissimilar surface and subsurface soils

Degradation and sorption/desorption are important processes affecting the leaching of pesticides through soil. This research characterized the degradation and sorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine) in Drummer (silty clay loam) and Exeter (sandy loam) surface soils and their corresponding subsurface soils using sequential extraction methods over 400 days. By the end of the incubation, approximately 55% of imidacloprid applied at a rate of 1.0 mg kg^?1 degraded in the Exeter sandy loam surface and subsurface soils, compared to 40% of applied imidacloprid within 300 days in Drummer surface and subsurface soils. At the 0.1 mg kg^?1 application rate, dissipation was slower for all four soils. Water-extractable imidacloprid in Exeter surface soil decreased from 98% of applied at day 1 to > 70% of the imidacloprid remaining after 400 d, as compared to 55% in the Drummer surface soil at day 1 and 12% at day 400. These data suggest that imidacloprid was bioavailable to degrading soil microorganisms and sorption/desorption was not the limiting factor for biodegradation. In subsurface soils > 40% of ¹⁴C-benzoic acid was mineralized over 21 days, demonstrating an active microbial community. In contrast, cumulative ¹⁴CO₂ was less than 1.5% of applied ¹⁴C-imidacloprid in all soils over 400 d. Qualitative differences in the microbial communities appear to limit the degradation of imidacloprid in the subsurface soils.