有机磷农药降解菌及其基因工程研究新进展

有机磷农药是目前我国使用量最大的农药,对农业的发展有重要的作用,但同时造成了严重的环境污染.利用微生物及其产生的降解酶来降解农药是行之有效的方法.随着分子生物学技术的深入利用,农药的微生物降解已在基因工程领域取得了很大进展.本文综述了有机磷农药降解微生物的筛选、降解酶和基因的克隆、基因工程菌的构建以及应用等几个方面的研究进展.     

有机磷农药微生物降解研究进展

微生物降解是有机磷农药在环境中去毒降解的主要方式,是治理环境污染的一项有效手段。该文综述了有机磷农药降解菌的分离鉴定、降解机理与代谢途径、降解基因的克隆及表达、降解菌制剂和酶制剂的应用、以及有机磷农药微生物降解研究趋势五个方面的研究现状。     

微生物降解农药研究的新进展

农药尤其是化学农药中高毒、高残留、难降解的农药是重要的环境污染物,而利用微生物治理农药所造成的环境污染是一项有效的手段。从降解农药的微生物的种类、工程菌的构建、微生物降解农药的机理、降解特性、影响因素及应用效果等多方面综述了近年来的研究进展,并提出了微生物降解农药研究领域的发展趋势和有待进一步解决的一些突出问题。     

新技术在农药微生物降解中的应用

近年来,分子生物学及基因工程的迅猛发展,克服了农药微生物降解传统研究中存在的障碍,为农药微生物降解的研究开辟了新的途径。综述了固定化技术、基因工程、多菌复合体的构建以及细胞表面展示技术在农药微生物降解中的应用,并对新技术在农药微生物降解中的应用前景作出了展望。     

微生物降解有机磷农药污染的研究进展

有机磷农药严重污染生态环境,微生物降解是治理有机磷农药污染的新技术,综述了降解有机磷农药污染的微生物种类、降解的机理、应用、存在的问题及今后研究方向。     

微生物降解有机磷农药酶促机制

有机磷农药污染严重,微生物有机磷农药是治理有机磷农药残留的新技术,综述有机磷农药降解酶的研究现状、酶促作用机理、基因工程等方面的研究现状。     

有机磷农药的微生物降解研究进展

微生物因种类和代谢多样性在有机磷农药降解中表现出独特的优势。对微生物降解有机磷农药的机制、微生物的获得、基因工程菌的构建及研究展望进行了综述。     

煤微生物降解研究进展

煤是重要的化石燃料,但其不合理利用造成了资源浪费和环境污染等问题,煤微生物降解是煤在微生物的作用下将煤这种具有复杂结构的大分子降解成可利用小分子的过程。根据作用微生物的不同主要将其分为真菌和细菌两种降解方式。本研究从碱性物质、螯合剂、酶促以及降解基因等方面,综述了真菌类和细菌类微生物在煤降解方面的研究进展,比较了煤微生物降解相对于化学降解和热降解的优越性,并总结了煤微生物降解研究过程中存在的几点问题及研究思路。煤的微生物降解将在减少环境污染、缓解能源危机等方面发挥巨大作用。     

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。     

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。     

Impact of pesticides on soil microbiological parameters and possible bioremediation strategies

Intensive agriculture is spectacularly successful since last couple of decades due to the inputs viz; fertilizers and pesticides along with high yielding varieties. The mandate for agriculture development was to feed and adequate nutrition supply to the expanding population by side the agriculture would be entering to into new area of commercial and export orientation. The attention of public health and proper utilization natural resources are also the main issues related with agriculture development. Concern for pesticide contamination in the environment in the current context of pesticide use has assumed great importance [1]. The fate of the pesticides in the soil environment in respect of pest control efficacy, non-target organism exposure and offsite mobility has been given due consideration [2]. Kinetics and pathways of degradation depend on abiotic and biotic factors [6], which are specific to a particular pesticide and therefore find preference. Adverse effect of pesticidal chemicals on soil microorganisms [3], may affect soil fertility [4] becomes a foreign chemicals major issue. Soil microorganisms show an early warning about soil disturbances by foreign chemicals than any other parameters. But the fate and behavior of these chemicals in soil ecosystem is very important since they are degraded by various factors and have the potential to be in the soil, water etc. So it is indispensable to monitor the persistence, degradation of pesticides in soil and is also necessary to study the effect of pesticide on the soil quality or soil health by in depth studies on soil microbial activity. The removal of metabolites or degraded products should be removed from soil and it has now a day’s primary concern to the environmentalist. Toxicity or the contamination of pesticides can be reduced by the bioremediation process which involves the uses of microbes or plants. Either they degrade or use the pesticides by various co metabolic processes.     

Stability and Effects of Some Pesticides in Soil

The influence of 29 pesticides on CO(2) production and nitrification by soil microorganisms was determined. A few compounds were stable but without significant effect in soil (chlorinated hydrocarbons), some persisted and depressed respiration and nitrification (carbamates, cyclodienes, phenylureas, thiolcarbamates), and others displayed toxicity but were transformed by soil microorganisms (amides, anilides, organophosphates, phenylcarbamates, triazines). Some compounds of the last type induced an initial increase and subsequent decrease in CO(2) production by soil. No simple explanation of this effect is possible, but the results of studies of model systems having established activities suggest that in soil any one or a combination of the following mechanisms is responsible for the observed complex relation of CO(2) production to time: (i) a pesticide acts to uncouple oxidative phosphorylation in a manner analogous to 2,4-dinitrophenol; (ii) a pesticide lacking antimicrobial action is oxidized in part and transformed to a stable and toxic product; (iii) a pesticide that is selectively toxic inhibits CO(2) production by sensitive microorganisms but is subject to oxidation without detoxification by other members of the microbial population that are resistant to its initial action. Pesticide concentrations greatly in excess of those recommended for agricultural and home use were required to produce an effect, and supplementary organic matter (glucose) tended to reduce pesticide toxicity and increase the microbial degradation of pesticides in soil.     

Pesticide relevance and their microbial degradation: a-state-of-art

The extensive use of pesticide causes imbalance in properties of soil, water and air environments due to having problem of natural degradation. Such chemicals create diverse environmental problem via biomagnifications. Currently, microbial degradation is one of the important techniques for amputation and degradation of pesticide from agricultural soils. Some studies have reported that the genetically modified microorganism has ability to degrade specific pesticide but problem is that they cannot introduce in the field because they cause some other environmental problems. Only combined microbial consortia of indigenous and naturally occurring microbes isolated from particular contaminated environment have ability to degrade pesticides at faster rate. The bioaugumentation processes like addition of necessary nutrients or organic matter are required to speed up the rate of degradation of a contaminant by the indigenous microbes. The use of indigenous microbial strains having plant growth activities is ecologically superior over the chemical methods. In this review, we have attempted to discuss the recent challenge of pesticide problem in soil environment and their biodegradation with the help of effective indigenous pesticides degrading microorganisms. Further, we highlighted and explored the molecular mechanism for the pesticide degradation in soil with effective indigenous microbial consortium. This review suggests that the use of pesticide degrading microbial consortia which is an eco-friendly technology may be suitable for the sustainable agriculture production.     

Development,registration and commercialization of microbial pesticides for plant protection

Plant protection against pathogens, pests and weeds has been progressively reoriented from a therapeutic approach to a rational use of pesticide chemicals in which consumer health and environmental preservation prevail over any other productive or economic considerations. Microbial pesticides are being introduced in this new scenario of crop protection and currently several beneficial microorganisms are the active ingredients of a new generation of microbial pesticides or the basis for many natural products of microbial origin. The development of a microbial pesticide requires several steps addressed to its isolation in pure culture and screening by means of efficacy bioassays performed in vitro, ex vivo, in vivo, or in pilot trials under real conditions of application (field, greenhouse, post-harvest). For the commercial delivery of a microbial pesticide, the biocontrol agent must be produced at an industrial scale (fermentation), preserved for storage and formulated by means of biocompatible additives to increase survival and to improve the application and stability of the final product. Despite the relative high number of patents for biopesticides, only a few of them have materialized in a register for agricultural use. The excessive specificity in most cases and biosafety or environmental concerns in others are major limiting factors. Non-target effects may be possible in particular cases, such as displacement of beneficial microorganisms, allergenicity, toxinogencity (production of secondary metabolites toxic to plants, animals, or humans), pathogenicity (to plants or animals) by the agent itself or due to contaminants, or horizontal gene transfer of these characteristics to non-target microorganisms. However, these non-target effects should not be evaluated in an absolute manner, but relative to chemical control or the absence of any control of the target disease (for example, toxins derived from the pathogen). Consumer concerns about live microbes due to emerging food-borne diseases and bioterrorism do not help to create a socially receptive environment to microbial pesticides. The future of microbial pesticides is not only in developing new active ingredients based on microorganisms beneficial to plants, but in producing self-protected plants (so-called plant-incorporated pesticides) by transforming agronomically high-value crop plants with genes from biological control agents     

Limitation of point source pesticide pollution: results of bioremediation system

Groundwater and surface water is at risk of contamination from the use of some agricultural pesticides. In many circumstances pesticide contamination of water resources is more likely to result from point sources than from diffuse sources following approved application to crops in the field. Such point sources include areas on farms where pesticides are handled, filled into sprayers or where sprayers are washed down. To overcome this way of contamination different kind of bio-remediation systems are nowadays in development. In Flanders, Belgium two pilot plants of bioremediation systems for the in situ retention and/or degradation of pesticides were installed. Both systems were based on the Phytobac concept, a watertight excavation filled with straw, peat, compost and soil. The channel was made in the bottom from plastic foil. All kinds of spray rests were captured by the phytobacs. This study focuses on what level pesticides leach, bio-degrade or are retained by the filling of the phytobac. The soil-properties of the filling were investigated. Pesticide tracers were added for monitoring to both phytobacs. Soil and water samples were taken during one year. Pesticides are retained at least for one month by the filling of the phytobac. Almost no pesticide leached out. In winter hardly any pesticide degradation was observed in the filling of the phytobac. In summer no detectable pesticides were still left in the phytobacs.     

2,4-D impact on bacterial communities, and the activity and genetic potential of 2,4-D degrading communities in soil

The key role of telluric microorganisms in pesticide degradation is well recognized but the possible relationships between the biodiversity of soil microbial communities and their functions still remain poorly documented. If microorganisms influence the fate of pesticides, pesticide application may reciprocally affect soil microorganisms. The objective of our work was to estimate the impact of 2,4-D application on the genetic structure of bacterial communities and the 2,4-D-degrading genetic potential in relation to 2,4-D mineralization. Experiments combined isotope measurements with molecular analyses. The impact of 2,4-D on soil bacterial populations was followed with ribosomal intergenic spacer analysis. The 2,4-D degrading genetic potential was estimated by real-time PCR targeted on tfdA sequences coding an enzyme specifically involved in 2,4-D mineralization. The genetic structure of bacterial communities was significantly modified in response to 2,4-D application, but only during the intense phase of 2,4-D biodegradation. This effect disappeared 7 days after the treatment. The 2,4-D degrading genetic potential increased rapidly following 2,4-D application. There was a concomitant increase between the tfdA copy number and the 14C microbial biomass. The maximum of tfdA sequences corresponded to the maximum rate of 2,4-D mineralization. In this soil, 2,4-D degrading microbial communities seem preferentially to use the tfd pathway to degrade 2,4-D.     

植物-微生物联合修复化学农药污染土壤的研究进展

化学农药的高毒性、生物积累性和扩散性极易对环境及人类健康造成危害,环境中化学农药的去除尤为重要。植物-微生物联合修复技术因其高效、环境友好和修复成本低等优点受到越来越多的关注,植物-微生物联合修复化学农药污染土壤是一种很有前景的方法。植物为根际和内生细菌提供养分,而细菌通过化学农药的降解和解毒来支持植物生长。本文综述了影响化学农药在植物体内吸收和转运的因素以及植物-微生物修复技术的原理,并讨论了植物与微生物在化学农药污染土壤修复中的协同效应,并对植物-微生物联合修复法在化学农药污染土壤修复中的应用前景进行了展望。     

Microorganisms resistant to heavy metals and toxic chemicals as indicators of environmental pollution and their use in bioremediation

Microorganisms present in water samples from various industrial effluents were analysed for their resistance to lead, chromium, and cadmium. The ability of these microorganisms to grow on or metabolize toxic hydrocarbons and pesticides was also checked. Microorganisms in samples from the steel and tanning industries were generally resistant to metal ions but were not capable of metabolizing toxic hydrocarbons. Conversely, microorganisms found in samples of pesticide and from the chemical industry were capable of metabolizing hydrocarbons and pesticides but were not much resistant to metal ions. Microorganisms from effluents of the paint industry and urban wastes were resistant to lead. A correlation between the population of microorganisms and the type of pollution was observed. Indigenous microorganism could be regarded as indicators of pollution and be used in various operations to resist, process, metabolize, and detoxify toxic industrial wastes.     

多种农药与次氯酸钠、高锰酸钾和高铁酸钾的反应活性

为探究4类,10种广泛使用的农药(苯氧羧酸类,芳香酸类,取代脲类和烟碱类)与3种氧化剂(次氯酸钠,高锰酸钾和高铁酸钾)的反应活性,本研究在温度(25±2)℃、pH值为8的条件下,分析10种农药分别与3种氧化剂NaClO、KMnO4、K2Fe O4在不同浓度下的反应活性,采用HPLC检测法,对比降解效能,探究氧化剂性质与有机物结构导致的反应活性的差异。实验结果表明,不同种类农药的结构性质对反应活性有重要影响,3种氧化剂的氧化降解能力有明显差异。苯氧羧酸类和芳香酸类农药结构较简单,并含有稳定的苯环或吡啶环结构,氧化降解较困难。取代脲类和烟碱类农药结构较复杂,氧化剂可攻击其不饱和官能团,反应活性较高。NaClO对取代脲类农药的降解率明显优于其他2种氧化剂,3种氧化剂对烟碱类农药的氧化降解效果依次为NaClO>KMn O4>K2Fe O4。研究多种农药与次氯酸钠、高锰酸钾和高铁酸钾的反应活性对降解去除水体中的农药残留对水环境的治理具有重要意义。