Biodegradation of metalaxyl in avocado soils
Biodegradation of metalaxyl in avocado soils
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DOI：
10.1094/phyto-75-135
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发表时间：
1985
期刊：
影响因子：
3.2
通讯作者：
A. Bailey;M. Coffey
中科院分区：
文献类型：
--
作者：
A. Bailey;M. Coffey
贝利，m.m.和科菲，m.d. 1985。甲螨灵在牛油果土壤中的生物降解。植物病理学75:135 - 137。使用一种敏感的生物测定方法，将疫霉菌作为先前处理过甲螨灵和类似的未经处理的土壤生物的试验，在5个不能降解杀菌剂的土壤中检测到3个甲螨灵的生物降解。在一段时间内反复施用杀菌剂的牛油果土壤中，通过使用选择性培养基或2-5年的时间，从这两种土壤中恢复了真菌和细菌微生物群。在这些土壤中，甲axyl的平均半衰期为28次过滤技术，能够在45天内降解甲axyl，在最活跃的土壤中，半衰期为14天。作曲期。一种能够降解甲氧基的土壤（14天内降解50%）和微生物种群（细菌、真菌和放线菌）的水平都不能促进丙烯酰胺类杀菌剂RE 26745和类似土壤的降解，无论是对甲氧基、草二酰还是化学相关除草剂异丙草胺的分解有活性还是无活性。没有不同。在之前的一项研究中，开发了一种灵敏的生物测定法来测定该杀菌剂的生物降解能力。调整土壤湿度以检测土壤中低浓度的甲乙基（N-[2,6-二甲基苯基]田间容量，每个样品相当于200 g烘箱干燥的N-[甲氧基乙酰]-丙氨酸甲酯）(1)。甲氨甲酯是一种土壤，与40 mg a.i.甲氨甲酯溶解在系统杀菌剂中，对2 ml甲醇的植物病原体有特异性活性，通过机械搅拌彻底混合，最终得到Peronosporales(2-5,11)，已经在植物中进行了研究（8-10）。浓度为2004g /g干重土壤。对于每种土壤，有两项非常少的研究评估了样品在23℃的黑暗中在单独的500毫升土壤中孵育的寿命和生物降解（1,7,12）。由于其低吸附性和高流动性，梅森罐。每个土壤都包括一个对照样品，其中2 ml甲醇是甲氨甲酯，可以从添加量低的沙质土壤中快速浸出。4个样品，每个样品由有机物组成（12）。在某些情况下，它也可能受到大约5克的土壤，在0,14,28,42,56时从每个罐子中取出，并进行微生物降解（1,12）。在严重疾病压力下，70天。对样品进行了处理和生物分析，如所述甲螨灵的广泛生物降解可能导致显着或先前(1)过早丧失杀真菌功效。微生物种群。本研究的目的是获得在添加甲螨灵之前确定的基本信息，方法是利用甲螨灵在牛油果土壤中的寿命，这些牛油果土壤在几年的时间里反复使用稀释板技术(6)和不同的杀菌剂应用，并为微生物群的主要成分选择培养基。在以前未用杀菌剂处理的土壤中。葡萄糖蛋白胨琼脂用于分离细菌，水琼脂用于分离放线菌，马丁玫瑰琼脂用于分离真菌。材料与方法不同土壤菌群的生物降解。从同一个牛油果林收集了两个土壤样本：一个是E9，是土壤。5种砂质壤土和砂质粘土壤土具有降解甲螨灵活性的历史，并且起源于杀真菌剂处理，以及典型的加利福尼亚南部种植牛油果（Persea处理过的场地；另一种，E7，起源于未处理的场地，和americana Mill.），显示没有降解杀菌剂的能力。研究氨甲酯生物降解的水分含量（表1）。在选择之前，每种土壤在500毫升梅森罐和样品中调整到现场容量，土壤A， B， C和D接受甲氨甲酯2年，样品由200克土壤（干重当量）组成，每次施用的速率为2.5克a.i./ m，每次施用三次，在饱和氯仿气氛中灭菌，干燥器一年。土壤E在5年的时间内以2天的速率在23℃下施用30次，然后对土壤进行曝气并重新施用2.05或4.10 gai。/ m。选择类似土壤的样品作为对照，这些土壤没有接受先前从这些甲螨中分离出的部分天然微生物群。相同的土壤。两种处理组成的5毫升水悬浮液对土中甲axyl的吸附系数。在加州郡（表1，土壤E5-9），从三个合适的真菌选择培养基中提取的沙子样品，从圣地亚哥福布鲁克的一个鳄梨树林中提取的壤土样品，使用102稀释，细菌使用105稀释，用于确定添加到土壤中的样品。此外，5-ml土壤提取物（1%,w/v）吸附甲axyl。土壤样品分别用5、10、15个细菌或真菌悬浮液处理，这些悬浮液使用每毫升20克甲叶醇（技术等级，94.3% a.i）， Millipore膜，SC 8。利用真菌从细菌中分离得到的孔径为- 1,4 m的等温线，或者用Sharom和Edgington（12）描述的细菌的孔径为0.45- 1,5 m的等温线。添加到土壤中的浓度。用微生物悬浮液处理过的土壤，用200 pga浓度的甲霜灵修饰的生物测定法测定了甲霜灵的含量。/g干重和Bailey和Coffey(1).在23℃的黑暗中孵育。对照由氯仿处理的土壤组成。土壤（表1）含有和不含200毫克甲氨酯每毫升。研究了土样处理的历史，以确定它们在0、14、28和45天从每个罐子中取出，并通过生物测定法确定存在的甲螨灵浓度(1)。这篇文章的出版费用部分由版面费支付。本文介绍了不同酰基苯胺类农药的生物降解。因此，根据美国法典第18编第1734条，该商品必须在此标记为“广告”，以表明这一事实。并与其他几种酰基苯胺类化合物比较了甲叶茅酯在土壤中的持久性。土壤E9，有效降解©1985 The American Phytopathological Society metaxyl并保持在田间容量，用Vol. 75, No. 2, 1985 135 200处理。结果：甲酰基（2-甲氧基- n-[2-氧基-1,3]）500 btg, RE 26745(2-甲氧基- n-[2,6-二甲基苯基]- n-[四氢-2-氧基-3)200 btg。5种不同土壤样品[2-乙基-6 -甲基苯基]- n -[2-甲氧基-甲基乙基]（E5, E6, E7， E8和E9）的甲氧基k值（相对呋喃基]-乙酰胺）或1000 Ag -甲草胺（2-氯-吸附量）为0.20（乙酰胺）每克土壤干重。样品含量分别为0.28、0.36、0.43和0.60 nmol /g。在0、14、28、42、56和70天进行生物测定，测定甲螨灵的生物降解水平。除了一种土壤苯酰胺化合物存在。原添加200 Mg甲藻醇后，土壤中大部分仍为酰基苯胺类化合物，其实际浓度（D1）是参照在没有甲藻醇处理过的分离物（p1257）生长响应历史标准曲线的土壤中70 d后的生物测定结果计算出来的。相比之下，在五分之三的土壤中，对每一个有甲螨灵处理史的土壤疫霉，杀菌剂不能是化学的。70天后检测（图1和图2）。土壤样品最活跃的Al-C D1-C E7 CONTROL A2-M D2-M E E9 METALAXYL BI jflllM EI-C B2-M E2-M Ci c3 - c C2-M E4-M•0
Bailey, A. M., and Coffey, M. D. 1985. Biodegradation of metalaxyl in avocado soils. Phytopathology 75:135-137. Using a sensitive bioassay involving Phytophthora boehmeriae as the test with a history of prior metalaxyl treatment and from similar untreated soils organism, biodegradation of metalaxyl was detected in three of five with no ability to degrade the fungicide. Fungal and bacterial microflora avocado soils that had received repeated applications of the fungicide over a were recovered from these two soils by using either selective media or period of 2-5 yr. The average half-life of metalaxyl in these soils was 28 filtration techniques and were capable of degrading metalaxyl over a45-day days, and in the most active soils the half-life was 14 days. The composition period. One soil capable of degrading metalaxyl (50% over 14 days) did not and levels of the microbial populations (bacteria, fungi, and actinomycetes) promote degradation of either the acylanilide fungicides RE 26745 and of similar soils, either active or inactive in the breakdown of metalaxyl, did oxadixyl, or the chemically related herbicide metolachlor. not differ. Active microbial populations were recovered both from soils In a previous study, a sensitive bioassay was developed for ability to biodegrade that fungicide. Soil moisture was adjusted to detecting low concentrations of metalaxyl (N-[2,6-dimethylphenyl]field capacity, and each sample, equivalent to 200 g of oven-dried N-[methoxyacetyl]-alanine methyl ester), in soils (1). Metalaxyl, a soil, was thoroughly mixed with 40 mg a.i. of metalaxyl dissolved in systemic fungicide active specifically against plant pathogens of the 2 ml of methanol by using mechanical agitation, to give a final order Peronosporales (2-5,11), has been studied in plants (8-10). concentration of 200 4g/g dry weight of soil. For each soil, two Very few studies have evaluated its longevity and biodegradation in samples were incubated in the dark at 23 C in separate 500-ml soils (1,7,12). Due to its low adsorption and high mobility, Mason jars. A control sample, to which 2 ml of methanol was metalaxyl can be rapidly leached from sandy soils which are low in added, was included for each soil. Four samples, each consisting of organic matter (12). In certain cases it also may be subject to about 5 g of soil, were removed from each jar at 0, 14, 28, 42, 56, and microbial degradation (1,12). Under severe disease pressure, 70 days. The samples were treated and bioassayed as described extensive biodegradation of metalaxyl could lead to a significant or previously (1). premature loss of fungicidal efficacy. Microbial populations. The microbial population of each soil The purpose of this study was to obtain basic information on the was determined before the addition of metalaxyl by using a longevity of metalaxyl in avocado soils that had received repeated combination of the dilution-plate technique (6) and different applications of the fungicide over a period of several years as well as selective media for the major components of the microflora. in soils not previously treated with the fungicide. Glucose peptone agar was used to isolate bacteria, water agar for actinomycetes, and Martin's rose-bengal agar for fungi. MATERIALS AND METHODS Biological degradation by different soil microflora. Two soil samples were collected from the same avocado grove: one, E9, was Soils. Five sandy loam and sandy clay loam soils with a history of active in degrading metalaxyl and originated from a fungicidemetalaxyl treatment, and typical of those in which avocado (Persea treated site; the other, E7, originated from an untreated site, and americana Mill.) is cultivated in southern California, were selected showed no capacity to degrade the fungicide. The moisture content to study biodegradation of metalaxyl (Table 1). Prior to selection of each soil was adjusted to field capacity in 500-ml Masonjars and of the samples, soils A, B, C, and D received metalaxyl for 2 yr at a a sample, consisting of 200 g of soil (dry weight equivalent), was rate of 2.5 g a.i./ m per application, with three applications per sterilized in a saturated chloroform atmosphere inside a dessicator year. Soil E received 30 applications over a period of 5 yr at rates of for 2 days at 23 C. The soils were then aerated and reinfested with 2.05 or4.10ga.i./m . Samples of similar soils that had not received portions of the natural microflora isolated previously from these metalaxyl were selected as controls. same soils. Two treatments consisting of a 5-ml aqueous suspension Coefficients for metalaxyl soil adsorption. Samples of a sandy from three plates of the appropriate selective medium for fungi, loam soil taken from an avocado grove in Fallbrook, San Diego using the 102 dilution, and bacteria using the 105 dilution, were County, CA (Table 1, soils E5-9) were used to determine the added to the soils. Additionally, 5-ml soil extracts (1%, w/v) adsorption of metalaxyl. Soil samples were treated with 5, 10, 15, consisting of either bacterial or fungal suspensions obtained using and 20 gg of metalaxyl (technical grade, 94.3% a.i.) per milliliter, Millipore membranes, a SC 8 . -,4m pore size for separation of and adsorption isotherms were obtained by using the method fungi from bacteria, or an HA 0.45-,m pore size for bacteria, were described by Sharom and Edgington (12). Concentrations of added to soils. Soils treated with microbial suspensions were metalaxyl were determined by using the bioassay described by amended with metalaxyl at 200 pga.i./g dry weight and incubated Bailey and Coffey (1). in the dark at 23 C. Controls consisted of chloroform-treated soils Biodegradation of metalaxyl in soils. The soils (Table 1) with a with and without 200 Mg a.i. of metalaxyl per milliliter. Soil samples history of metalaxyl treatment were studied to determine their were removed from each jar at 0, 14, 28, and 45 days and the concentration of metalaxyl present was determined by using the bioassay (1). The publication costs of this article were defrayed in part by page charge payment. This Biodegradation of different acylanilide pesticides. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. § 1734 solely to indicate this fact. persistence of metalaxyl in soil was compared to that of several other acylanilide compounds. Soil E9, active in degrading ©1985 The American Phytopathological Society metalaxyl and maintained at field capacity, was treated with either Vol. 75, No. 2, 1985 135 200 .g of metalaxyl, 500 btg of oxadixyl (2-methoxy-N-[2-oxo-1,3RESULTS oxazalidin-3-yl]-acet-2',6'-xylidine), 200 /ug of RE 26745 (2met hoxyl-N-[2,6-dimethylphenyl]-N-[tetrahydro-2-oxo-3Coefficients for metalaxyl soil adsorption. The Kvalues (relative furanyl]-acetamide), or 1000 Ag metolachlor (2-chloro-Nmeasure of adsorption) for metalaxyl of five different soil samples [2-ethyl-6methylphenyl]-N-[2-methoxy1-methylethyl] (E5, E6, E7, E8, and E9) from the same avocado grove were 0.20, acetamide) per gram dry weight of soil. The samples were 0.28, 0.36, 0.43, and 0.60 nmoles/g, respectively. bioassayed at 0, 14, 28, 42, 56, and 70 days for the level of Biodegradation of metalaxyl. With the exception of one soil phenylamide compound present. Actual concentrations of the (D1), most of the original 200 Mg of metalaxyl added was still acylanilides present in soils were calculated by reference to detected by the bioassay after 70 days in soils with no prior history standard curves of the growth responses of an isolate (P 1257) of of metalaxyl treatment. In contrast, in three out of five of the soils Phytophthora boehmeriae Sawada that were determined for each with a history of metalaxyl treatment, the fungicide could not be chemical. detected after 70 days (Figs. 1 and 2). The soil samples most active Al-C D1-C E7 CONTROL A2-M D2-M E E9 METALAXYL BI jflllM EI-C B2-M E2-M Ci c E3-C C2-M E4-M •0