二氯喹啉酸对农田生态系统的影响及其微生物降解研究进展

Research progress in farmland ecological effects and microbial degradation of quinclorac

在总结国内外研究成果的基础上,较全面地综述了典型喹啉羧酸类除草剂二氯喹啉酸对作物、动物、土壤微生物群落结构和酶活性的影响,以及微生物降解方面的研究进展,并对未来从分子生物学层面研究二氯喹啉酸微生物降解机制、降解菌筛选以及田间实际应用等方面进行了展望。主要内容如下:土壤中残留的二氯喹啉酸会引起作物体内相关基因及功能酶的变化,从而对后茬作物产生药害;环境中的二氯喹啉酸可能会引起动物生长发育不良、变态发育以及生殖异常,进而影响自然界动物的多样性和丰度;正常施用量的二氯喹啉酸对土壤微生物群落结构和土壤酶活性影响不大;二氯喹啉酸在自然环境土壤中残留时间长,基于微生物降解的生物修复是治理二氯喹啉酸污染土壤的一种有效途径;目前研究者从二氯喹啉酸污染土壤和烟草根部分离出的二氯喹啉酸高效降解菌株大多是细菌;二氯喹啉酸的降解可能是脱羧反应和脱氯反应2种路径共同作用的结果;温、湿度和p H是影响土壤中二氯喹啉酸微生物降解的主要因素。为探明土壤微生物降解二氯喹啉酸的复杂生理生化过程及机制,研发二氯喹啉酸污染土壤修复技术,今后应利用先进的分子生物学技术和质谱联用技术研究二氯喹啉酸逐级降解产物,筛选功能降解菌株,通过遗传工程构建二氯喹啉酸高效降解菌剂,并进一步加强多种降解菌株的复合降解研究,验证二氯喹啉酸功能降解菌株在田间复杂环境中的实际效果。

Quinclorac is one of the typical quinolinecarboxylic acid herbicides existing in farmland ecosystems. The research progress in effect of quinclorac on crops, community structure of soil microorganisms, enzyme activities and its degradation by microorganisms was reviewed comprehensively. The future works focusing on mechanisms of microbial degradation, screening of degradative bacteria, and application in farmlands were also proposed. The main contents are as follows： Quinclorac is relatively stable in the environment; quinclorac residues in soil can lead to changes of genes and functional enzymes in crops, thus causing damage to crops and resistance of some weeds; the presence of quinclorac in environment may cause animal dysplasia, metamorphosis and reproductive abnormality, thus affecting the diversity and abundance of animals; regular application rate has little effect on community structure of soil microorganisms and soil enzyme activities. Quinclorac often exists for a long time in natural environment, and the bioremediation based on microbial degradation is an effective way to control the quinclorac pollution. At present, researches on microbial degradation of quinclorac are conducted mainly in China, and several highly effective strains for degrading quinclorac isolated from contaminated soils and tobacco roots are mostly identified as bacteria. The degradation of quinclorac may attribute to the combination of decarboxylation reaction and dechlorination reaction. Temperature, humidity and p H are the main influencing factors of microbial degradation. Usually in a certain range, the degradation of quinclorac in soil accelerated with the increase of temperature and humidity. However, excessively high temperature or humidity would reduce the efficiency of microbial degradation. p H value mainly affected the microbial degradation of quinclorac in two aspects. Quinclorac is weak acidic and shows higher dissociation degree in slight alkaline soil, which is more easily degraded; on the other hand, the p H of soil has direct effect on the species and quantity of soil microbial communities,which has a great impact on the effect of microbial degradation. In conclusion, to reveal the complex physiological and biochemical processes and mechanism of soil microbial degradation, and explore the remediation technology for quinclorac contaminated soil, future work should focus on： 1） investigating the mechanism of quinclorac degradation at molecular biological level by the application of advanced molecular biological technology and tandem mass spectrometry technology,and constructing highly effective strains in degrading quinclorac through genetic engineering; 2） focusing on complex degradation of quinclorac by multiple strains; 3） verifying the effect of the currently isolated quinclorac-degrading strains in the field.