拟除虫菊酯类农药降解菌及降解酶的研究概况

拟除虫菊酯类农药目前已成为我国出口的蔬菜、水果中主要的3类农药残留之一, 引起急慢性中毒事件也越来越多, 对人类、水生生物和自然环境造成很大危险。而农药生物降解作为去除农药污染的有效手段, 逐渐成为环境科学研究的热点。重点综述了拟除虫菊酯类农药降解菌的分离、降解酶的提取、纯化、降解机理、固定化研究, 并对以后要解决的问题进行了展望。     

环境中拟除虫菊酯类农药微生物降解技术研究进展

近年来,随着拟除虫菊酯类农药的大量及不合理使用,环境及食品中的农药残留对人类健康造成的负面影响日益显著。微生物降解农药作为去除农药污染安全高效的方法已成为当前研究热点之一。综述了国内外拟除虫菊酯类农药微生物降解菌的种类、降解机制、降解酶及降解菌应用的最新研究进展,并对亟须解决的重要问题进行了展望。     

茶叶上拟除虫菊酯类农药降解菌的分离及其特性

生物修复对降解污染基质中的农药是一种对环境有益的方法。目标是要寻找能够降解在茶叶生产中使用的拟除虫菊酯类农药的降解菌。最终在福州某茶园经农药处理过的茶叶中分离降解菌。首先在富集培养基中筛选,接着在以农药为唯一碳源的基础培养基中连续筛选。结果发现,其中一株标号为c1f6的菌株生长的特别良好,经AMS-VITEK120全自动微生物分析系统鉴定,为假单胞菌属的一个未知种。采用HP6890气相色谱仪测定菌株对拟除虫菊酯类农药联苯菊酯、甲氰菊酯和氯氰菊酯的降解率。在pH7.0的基础培养基发酵液中,以各加100mg·L-1这3种农药为唯一碳源,30℃振荡培养,接种c1f6后3d,这3种农药的降解率分别为55.64%、44.56%和52.19%。采用光密度测定的菌株生长值和农药降解率的关系曲线表明,在基础培养基中,农药降解和菌株生长成正相关,说明菌株能以拟除虫菊酯类农药为唯一碳源和能源进行生长。采用同样的方法测定表明,菌株c1f6对有机磷农药也有一定的降解力,3d对甲胺磷和毒死蜱的降解率分别为27.67%和12.35%。因此,假单胞菌c1f6是一株较广谱的农药降解菌,有望用于生物修复过程,以减少茶叶栽培过程中的产品和环境污染。     

拟除虫菊酯类农药降解菌的紫外线诱变

拟除虫菊醑类农药降解菌阴沟肠杆菌(Enterobacter cloacap)w10j15菌株经紫外线诱变后,筛选出突变株55株。分别在30℃,转速180rpm条件下培养3d,测降解力,获得正突变菌株6株,经加药普通斜面传种10代,2株(UW19,UW2)降解力保持稳定。降解力较强的UW19对联苯菊醑、甲氰菊醑、氯氰菊醑的降解率分别达70．40％、84．04％、70．87％,比出发菌株降解率提高了近20％;UW2也比出发菌株提高了约10％的降解率。     

拟除虫菊酯类农药对茶树害虫的生物活性与残留降解

本文报道了溴氰菊酯、联苯菊酯、氯氰菊酯、顺式氯氰菊酯、杀灭菊酯、功夫菊酯和二氯苯醚菊酯等七种拟除虫菊酯类农药对茶树主要害虫的杀虫效果和在茶树叶片上的降解动态试验结果.上述七种拟除虫菊酯类农药对鳞翅目茶树害虫的幼虫都具有极高的毒力,但对其他害虫的活性谱则表现有差异.它们在茶树芽梢上的降解速率常数为0.20—0.28天^-1,在茶树上的半衰期为2.5—3.5天,明显较有机磷农药稳定.在影响降解的因素中,挥发、热分解、雨水淋洗的作用不大,由茶梢生长稀释所起的作用较为明显.鲜叶中的农药残留在加工过程中的降解率为15—45%,平均20%,远低于有机磷农药.成茶中的残留农药在泡茶过程中由于他们的低水溶性,因此浸出率很低,一般仅有1—4.5%.     

拟除虫菊酯类杀虫剂对蜜蜂的毒性和影响

蜜蜂是最重要的农业授粉昆虫之一,蜜蜂在授粉过程中极有可能接触到广泛使用的广谱杀虫剂-拟除虫菊酯,大多数拟除虫菊酯对蜜蜂等农业授粉昆虫有较高的毒性.本文对拟除虫菊酯类杀虫剂的作用机理进行了综述;总结了蜂群及蜂产品中拟除虫菊酯类杀虫剂的残留现状、拟除虫菊酯对蜜蜂的急性毒性以及亚致死效应,讨论了拟除虫菊酯类杀虫剂复配农药对蜜...     

微生物降解3-苯氧基苯甲酸的研究进展

摘要:3-苯氧基苯甲酸(3-phenoxybenzoic acid,3-PBA)作为大多数拟除虫菊酯类农药的降解产物之一,在自然环境中难以降解,具有雌激素毒性,严重威胁到食品安全及人体健康。微生物对拟除虫菊酯及其中间产物(3-PBA)的降解已成为近年来的研究热点。本文从降解3-PBA的微生物种类、降解酶及降解基因、降解途径等方面进行了综述,对3-PBA生物降解机理、3-PBA降解酶基因工程菌构建的研究方向进行了展望,以期为微生物降解3-PBA的研究提供参考。     

微生物对拟除虫菊酯类农药残留的生物修复

拟除虫菊酯类农药是一类高效、广谱农药,且具有低毒性和能被生物降解之特性,但其残留却给人们的健康带来了巨大的威胁,如何有效地去除其残留成为摆在环境工作者面前的一项重大课题。以生物修复为理论基础的农药残留降解菌技术为解决这一难题带来了新思路,该方法操作简便、经济实用,在国内外均成为环境工作者的研究热点。     

拟除虫菊酯农药降解菌HP-S-01培养基的筛选及优化

通过比较高氏合成1号培养基、查彼氏培养基、马铃薯葡萄糖培养基、燕麦片培养基和理查德培养基等5种培养基对拟除虫菊酯农药降解菌Streptomyces sp.HP-S-01生长的影响,确定了高氏合成1号培养基为菌株生长最适宜的培养基.以高氏合成1号培养基为基础培养基,采用中心组分旋转设计法(RRCD)和响应曲面法(RSM),优化了培养基关键组分中可溶性淀粉、硝酸钾和磷酸氢二钾的组成,以降解率为主要衡量指标,最佳配方包括可溶性淀粉25.9549 g/L、硝酸钾1.9975 g/L和磷酸氢二钾0.9505 g/L,最终优化出的培养基处理1 d后对50 mg/L高效氯氰菊酯的降解率达到99.61%,与期望降解率99.92%相一致,比优化前84.10%提高了15.51%.     

福州市蔬菜农药残留检测与分析

采用农业行业标准NY/T761-2008检测方法,用气相色谱仪对福州市3家超市和3家农贸市场销售的16个蔬菜品种共60份样品进行有机氯及拟除虫菊酯类农药残留的检测,并根据GB2763 - 2005标准判定检出超标情况.结果表明:农药残留检出率为31.67％;农药残留超标率为3.33％.从蔬菜种类上,白菜类、瓜类的检出率...     

乙酰胆碱酯酶的定点突变法设计及其在生物传感器领域的应用

有机磷和氨基甲酸酯类杀虫剂抑制乙酰胆碱酯酶(AChE)的天然生物活性。近年来,AChE作为生物识别元素的生物传感器在杀虫剂残留量检测领域受到了广泛的关注。简要分析了AChE结构与功能关系,综述了近年来通过定点突变法设计AChE以增加对各种杀虫剂的检测灵敏度及其在生物传感器领域的应用现状,指出多种灵敏的AChE突变体同时被应用于多样品及多分析物的平行检测体系是该领域进一步的发展方向。     

Evaluating the fitness consequences of plasticity in tolerance to pesticides

In a rapidly changing world, phenotypic plasticity may be a critical mechanism allowing populations to rapidly acclimate when faced with novel anthropogenic stressors. Theory predicts that if exposure to anthropogenic stress is heterogeneous, plasticity should be maintained as it allows organisms to avoid unnecessary expression of costly traits (i.e., phenotypic costs) when stressors are absent. Conversely, if exposure to stressors becomes constant, costs or limits of plasticity may lead to evolutionary trait canalization (i.e., genetic assimilation). While these concepts are well‐established in theory, few studies have examined whether these factors explain patterns of plasticity in natural populations facing anthropogenic stress. Using wild populations of wood frogs that vary in plasticity in tolerance to pesticides, the goal of this study was to evaluate the environmental conditions under which plasticity is expected to be advantageous or detrimental. We found that when pesticides were absent, more plastic populations exhibited lower pesticide tolerance and were more fit than less plastic populations, likely avoiding the cost of expressing high tolerance when it was not necessary. Contrary to our predictions, when pesticides were present, more plastic populations were as fit as less plastic populations, showing no signs of costs or limits of plasticity. Amidst unprecedented global change, understanding the factors shaping the evolution of plasticity will become increasingly important.     

The effect of some pesticides in conjunction with nitrogen sources on growth and carbohydrate and nitrogen constituents of sugarcane during formative phase

Summary The effect of gamma isomer of benzene hexachloride and Telodrin both in absence and presence of ammonium and nitrate nitrogen carriers on shoot and root growth and carboydrate and nitrogen constituents of sugarcane was studied. The pesticides induced shoot emergence and development of tillers and roots. Shoot growth, nitrogen intake and insoluble nitrogen content invariably increased by pesticide application while soluble carbohydrate and soluble nitrogen content of the shoot decreased. Pesticides also increased the water-soluble nitrate content of the soil.The effect of pesticides was not confined to ammonical source of nitrogen rather the pesticides proved equally effective under nitrate source of nitrogen and also in absence of additional nitrogen. Beneficial effect of pesticides on growth and development of sugarcane appears largely on account of more efficient utilisation of soil and fertilizer nitrogen. The results raise an interesting possibility of using these pesticides as growth stimulators to increase the efficiency of sugarcane plants growing under sub-optimal conditions of nitrogen     

酶修复土壤农药污染的研究进展

1　农药生物修复的重要性和紧迫性农药是人们主动投放于环境中数量最大、毒性最广的一类化学物质 [1] ,据统计 [2 ,5] ,1 960年世界农药的销售额仅为 8.5亿美元 ,1 994年增加到 2 78亿美元 ,增长 32 .71倍。在我国 ,农药至少占农业生产费用的 3% ,每年施用量 5.0× 1 0 5～ 6.0× 1 0 5t,其中约 80 %的农药直接进入环境 ,导致现有耕地的 1 /7受到不同程度污染 ,过量施用的农田约 1 .33×1 0 6ha,可见 ,农药已成为土壤主要污染源之一。同时由于土壤中农药 [4 ]的化学性质比较稳定 ,不易分解 ,如 DDT分解 95%需 4～ 30年 ,六六六 3～ 2 0年 …     

Bacillus amyloliquefaciens GA1 as a source of potent antibiotics and other secondary metabolites for biocontrol of plant pathogens

Background  

Phytopathogenic fungi affecting crop and post-harvested vegetables are a major threat to food production and food storage. To face these drawbacks, producers have become increasingly dependent on agrochemicals. However, intensive use of these compounds has led to the emergence of pathogen resistance and severe negative environmental impacts. There are also a number of plant diseases for which chemical solutions are ineffective or non-existent as well as an increasing demand by consumers for pesticide-free food. Thus, biological control through the use of natural antagonistic microorganisms has emerged as a promising alternative to chemical pesticides for more rational and safe crop management.     

Mini-review highlighting toxic effects of triflumuron in insects and mammalian systems

Pesticides have been used to kill pests such as insects, fungi, rodents, and unwanted plants. As these compounds are potentially toxic to the target organisms, they could also be harmful to human health and the environment. Several chronic adverse effects have been identified even after months or years of exposure. The adverse effects of pesticides on the agricultural ecosystem have been a matter of concern in recent decades. In this review, we present an overview of the studies, including our previous studies, monitoring currently used pesticides in the Tunisian agricultural soils that belong to the class of insect growth regulators (IGRs). Triflumuron (TFM) is a benzoyl phenyl urea insecticide belonging to the class of IGRs. TFM is widely used around the world to increase crop yield by protecting them from damage caused by insects. TFM works by inhibiting the synthesis of chitin, an essential part of the insect cuticle, making it susceptible to pathogens and deformities. Consequently, insects become more susceptible to pathogens and malformations. However, studies revealing its toxicity and its mode of action in mammalian systems remain very limited. The aim of this review is to better inform the community about the impact of TFM on crops, the environment, and human beings by summarizing its toxic effects.     

Pesticides DEET,fipronil and maneb induce stress granule assembly and translation arrest in neuronal cells

Pesticides entering our body, either directly or indirectly, are known to increase the risk of developing neurodegenerative disorders. The pesticide-induced animal models of Parkinson's disease and Alzheimer's disease recapitulates many of the pathologies seen in human patients and have become popular models for studying disease biology. However, the specific effect of pesticides at the cellular and molecular levels is yet to be fully established. Here we investigated the cellular effect of three commonly used pesticides: DEET, fipronil and maneb. Specifically, we looked at the effect of these pesticides in the formation of stress granules and the concomitant translational arrest in a neuronal cell line. Stress granules represent an ensemble of non-translating mRNAs and appear in cells under physiological stress. Growing evidence indicates that chronic stress may covert the transient stress granules into amyloids and may thus induce neurodegeneration. We demonstrate here that all three pesticides tested induce stress granules and translation arrest through the inactivation of the eukaryotic initiation factor, eIF2α. We also show that oxidative stress could be one of the major intermediary factors in the pesticide-induced stress granule formation and that it is a reversible process. Our results suggest that prolonged pesticide exposure may result in long-lived stress granules, thus compromising the neuronal stress response pathway and leading to neurodegeneration.     

Chemical Contamination of California Drinking Water

Drinking water contamination by toxic chemicals has become widely recognized as a public health concern since the discovery of 1,2-dibromo-3-chloropropane in California''s Central Valley in 1979. Increased monitoring since then has shown that other pesticides and industrial chemicals are present in drinking water. Contaminants of drinking water also include naturally occurring substances such as asbestos and even the by-products of water chlorination. Public water systems, commercially bottled and vended water and mineral water are regulated, and California is also taking measures to prevent water pollution by chemicals through various new laws and programs.     

Frequency of sister-chromatid exchange among greenhouse farmers exposed to pesticides

Sister-chromatid exchange (SCE) was measured in peripheral lymphocytes of 104 greenhouse farmers exposed to pesticides and 44 unexposed workers. The results of SCEs are expressed in two variables: (a) mean number of SCEs per chromosome and, (b) proportion of high frequency cells (cells with more than eight SCEs). A high correlation was found between these two variables. The adjusted means of both SCEs variables were significantly higher among the farmers compared with the unexposed group (P < 0.01). Adjustment was made for smoking, age, education, and origin.The adjusted means of both SCE variables, were significantly elevated (P < 0.05) among the farmers who prepared and applied more than 70% of the pesticides by themselves compared with those who prepared and applied less than 70% of the pesticides by themselves. Both SCEs variables were also significantly elevated (P < 0.05) among farmers who were involved in more than 7.4 sprays per year compared with those with 7.4 or less sprays per year (P < 0.05). We found a tendency towards elevation of the two variables of SCEs among those who did not use protective measures while preparing the pesticides.Evaluation of the influence of years of exposure on the frequency of SCEs showed that the two variables of SCEs were higher among those farmers who were exposed to pesticides for more than 21 years than among those with less than 21 years of exposure. The variables that had the most influence on the elevation of SCEs were self-preparation of the pesticide mixtures and the number of sprayings per year. Because the farmers used a mixture of almost 24 different chemical classes it was impossible to attribute exposure to a specific pesticide or group of pesticides to single farmers.Our finding of a significant increase of SCEs frequency in peripheral lymphocytes in greenhouse farmers indicates a potential cytogenetic hazard due to pesticides exposure.