富营养化水体微生物除藻试验

简要介绍利用微生物群技术(effectivemicroorganisms,简称EM)进行除藻试验的方法以及除藻效果的分析。试验结果表明投放EM初期对去除蓝藻(尤其是优势种铜锈微囊藻)有一定效果,试验后期除蓝藻效果逐渐消失。     

Use of Azotobacter sp.as an indicator to detect the toxicity of heavy metals in soils

A physiological strain of microorganism - Azotobacter sp. has been adopted as an indicator to detect the toxicity of heavy metals in soils. The concentration of heavy metals to which Azotobacter sp. was behaving initially to have the resistance to heavy metals is defined as the critical poisoning concentration. The method of physiological threshold adopted can have a quantitative determination with reproducible results. The determined critical poisoning concentration is basically consistent with the results of heavy metals and arsenic toxicities to the bacteria reported recently in literatures. Total 9 typical soils, including 6 zonal soils and 3 purple soils, in the whole country were determined for the toxicities of 5 heavy metals and arsenic to Azotobacter sp. that resulted in 48 critical poisoning concentrations.     

绿色荧光蛋白分子标记在环境微生物学研究中的应用

绿色荧光蛋白(green fluorescent protein,GFP)分子标记是现有遗传标记中最简单方便的一种方法，GFP及GFP突变体在微生物降解污染物、生物膜菌群构架、环境生态学和环境检测生物传感器等研究领域取得了很好的应用效果。     

微生物还原浸出法回收废旧电池粉末中的金属锰

驯化培养K1、K2、K33株锰还原异养微生物,使微生物耐受电池重金属离子的能力提高。通过微生物的还原作用将二氧化锰还原成二价锰离子回收利用。微生物利用MnO2作为代谢呼吸链最终电子受体,传递氧化有机物产生的电子,还原溶浸锰于介质中。与其他菌株相比,K1菌株表现出很强的金属耐受性,最终浸出率可达93%。     

Natural attenuation/phytoremediation in the vadose zone of a former industrial sludge basin

The natural attenuation of polyaromatic hydrocarbons (PAHs) in the vadose zone of a naturally revegetated former industrial sludge basin (0.45 ha) was examined. This was accomplished by comparing the concentration of 16 PAH contaminants present in sludge collected below the root zone of plants with contaminants present at 3 shallower depths within the root zone. Chemical analysis of 240 samples from 60 cores showed the average concentration of total and individual PAHs in the 0-30 cm, 30-60 cm, and bottom of the root zone strata were approximately 10, 20, and 50%, respectively, of the 16, 800 ppm average total PAH concentration in deep non-rooted sludge. Statistically significant differences in average PAH concentrations were observed between each strata studied and the non-rooted sludge except for the concentrations of acenaphthene and chrysene present at the bottom of the root zone in comparison to sludge values. The rooting depth of the vegetation growing in the basin was dependent on both vegetation type and plant age. Average rooting depths for trees, forbs (herbaceous non-grasses), and grasses were 90, 60, and 50 cm, respectively. The deepest root systems observed (100-120 cm) were associated with the oldest (12-14 year-old) mulberry trees. Examination of root systems and PAH concentrations at numerous locations and depths within the basin indicated that plant roots and their microbially active rhizospheres fostered PAH disappearance; including water insoluble, low volatility compounds, i.e. benzo(a)pyrene and benzo(ghi)perylene. The reduced concentration of PAHs in the upper strata of this revegetated former sludge basin indicated that natural attenuation had occurred. This observation supports the concept that through appropriate planting and management practices (phytoremediation) it will be possible to accelerate, maximize, and sustain natural processes, whereby even the most recalcitrant PAH contaminants (i.e. benzo(a)pyrene) can be remediated over time.     

应用选择器抑制污泥膨胀的20年实践

选择器是在控制丝状菌膨胀实践中孕育而生。丝状菌一般在基质浓度较低的条件下生长，基质浓度较高时菌胶团将要代替丝状菌。根据这一理论，选择器在２０年间逐渐地被开发出来。本文列举了一些成功例子的设计参数和具体结构，并指出了选择器的局限性，即它不能解决所有由丝状菌引起的问题。     

Evolution of plant volatile production in insect-plant relationships

Summary The production of volatile secondary plant substances during the evolution of terrestrial plants is reviewed in regard to the defensive systems of plants to microorganisms and herbivores. Plant volatiles can be produced by both anabolic and catabolic processes. Although attraction of pollinators is a well-studied phenomenon, functions of volatiles range from excretion of waste products to the production of compounds attracting natural enemies of herbivores. During the evolution of the angiosperms a diversity of volatiles were selected to defend generative parts against microorganisms. Many of these allomones were related to or even identical with sex pheromones of insects. As a result flowers of angiosperms became utilized as a mating site. Consequently insects visiting flowers became involved in pollination, facilitating the steps from anemophily to entomophily. The efficiency of entomophily was increased because of nutritional rewards.An evolutionary scenario for the impact of plant volatiles on insects is presented and the role of volatile allomones in the establishment of plant-insect relationships is emphasized by (1) their strong antimicrobial properties, (2) strategies to protect symbiotic microorganisms, (3) their function as repellents and deterrents, (4) the use of volatile allomones as kairomones. These facts speak for an adaptation of insects to plant physiology and a limited importance of phytophagous insects in selection pressure upon plants. Herbivorous insects have realized specific adaptations to be able to discriminate between complex odour blends, but the utilization of chemical groups among insect taxa is different.The main theories on plant chemical defence do not discuss the impact of volatiles on host plant selection and may be apt to revision when pheromones, allomones, kairomones and synomones are not taken into account.     

Comparison of the effects of aluminum and iron(III) salts on ultrafiltration membrane biofouling in drinking water treatment

Coagulation plays an important role in alleviating membrane fouling, and a noticeable problem is the development of microorganisms after long-time operation, which gradually secrete extracellular polymeric substances (EPS). To date, few studies have paid attention to the behavior of microorganisms in drinking water treatment with ultrafiltration (UF) membranes. Herein, the membrane biofouling was investigated with different aluminum and iron salts. We found that Al₂(SO₄)₃·18H₂O performed better in reducing membrane fouling due to the slower growth rate of microorganisms. In comparison to Al₂(SO₄)₃·18H₂O, more EPS were induced with Fe₂(SO₄)₃·xH₂O, both in the membrane tank and the sludge on the cake layer. We also found that bacteria were the major microorganisms, of which the concentration was much higher than those of fungi and archaea. Further analyses showed that Proteobacteria was dominant in bacterial communities, which caused severe membrane fouling by forming a biofilm, especially for Fe₂(SO₄)₃·xH₂O. Additionally, the abundances of Bacteroidetes and Verrucomicrobia were relatively higher in the presence of Al₂(SO₄)₃·18H₂O, resulting in less severe biofouling by effectively degrading the protein and polysaccharide in EPS. As a result, in terms of microorganism behaviors, Al-based salts should be given preference as coagulants during actual operations.     

Secretion-grooming in aquatic beetles (Hydradephaga): A chemical protection against contamination of the hydrofuge respiratory region

Summary All Hydradephaga investigated so far crawl onto land when exposed to an increase in water temperature and light intensity and spread the secretion from their pygidial glands over the body surface (secretion-grooming). The secretions have antimicrobial properties and are mainly applied to hydrofuge body regions important for aquatic respiration. Experimental prevention of secretion-grooming leads to the loss of the respiratory air bubble and a significant increase in mortality. These findings support the view that the secretion-grooming of adephagous aquatic beetles, like in some aquatic Heteroptera, inhibits the growth of microor-ganisms, thus preventing the contamination and wetting of the cuticular respiratory structures. Thus it keeps functional the air-retaining hydrophobous body regions essential for aquatic respiration. A model is presented on how secretion-grooming may have evolved in the Hydradephaga. Other possible functions of the pygidial gland secretions are discussed.     

蚯蚓活动对锌污染土壤微生物群落结构及酶活性的影响

以不同质量分数Zn污染高沙土为材料,研究在重金属污染土壤中,蚯蚓活动对土壤微生物数量和各种酶活性的影响。试验结果表明:Zn的加入使土壤蔗糖酶、脲酶活性降低,而对磷酸酶活性没有影响,加Zn量在300mg·kg-1以下时对微生物量碳有促进作用,高于该水平则表现为抑制作用。接种蚯蚓后,土壤细菌和放线菌的群落数明显提高,除各别处理外均达到显著差异,真菌数量没有变化;土壤磷酸酶、蔗糖酶、脲酶等酶活性也因接种蚯蚓而显著提高(p<0.05),随土壤Zn污染质量分数变化,蚯蚓对三种酶活性的影响趋势不同。蚯蚓活动对土壤酶活性的提高一定程度上缓解了重金属对酶的抑制作用。试验结果还表明蚯蚓活动显著提高了各处理土壤的NO3--N含量,相关散点图显示NO3--N含量和植物地上部生物量,地上部Zn质量分数及植物地上部Zn吸收总量间都有明显相关性(r=0.517,r=0.532,r=0.607)。试验初步验证了蚯蚓对Zn污染土壤中微生物和酶活性的改善作用。