甲基对硫磷降解菌PF32的分离鉴定及其降解特性研究

从某农药厂采集污泥,采用驯化富集的方式分离得到1株能以甲基对硫磷为唯一碳源生长的菌株,命名为PF32。根据表型特征 、生理生化特性和16S rRNA基因序列相似性分析,鉴定该菌株为寡养单胞菌Stenotrophomonas sp.。PF32能在24 h内降解浓度为100 mg/L的甲基对硫磷,降解率99%以上。PF32降解甲基对硫磷的最适pH值为7.0,最适温度为30℃,该菌降解甲基对硫磷的速率和起始接种量呈正相关。降解谱试验结果表明,PF32对辛硫磷、倍硫磷、杀螟硫磷、三唑磷、毒死蜱也有较好的降解效果。     

苍白杆菌B2对甲基对硫磷降解途径研究

采用薄层层析、紫外吸收光谱以及气谱-质谱联用的方法分析了苍白杆菌Ochrobacterum sp. B2降解甲基对硫磷的中间产物。结果表明,B2水解甲基对硫磷产生对硝基苯酚(PNP),PNP通过产生4-硝基邻苯二酚(4-nitrocatechol,4-NC)和1,2,4-苯三酚(1,2,4-benzenetriol) 的途径进一步代谢。苍白杆菌B2可以以PNP和4-NC为碳源生长,在菌的初始OD600值为0.02时,B2可在48 h内将50 mg/L的PNP完全降解, 在60 h内,将30 mg/L的4-NC完全降解。     

二氯喹啉酸降解菌的分离鉴定及降解特性分析

采用富集培养技术从长期施用二氯喹啉酸的土壤中分离得到1株能够降解二氯喹啉酸的细菌,将其命名为J3,通过生理生化特性和16s rDNA同源性序列分析,鉴定其为产碱菌属(Alcaligenes sp.)。在二氯喹啉酸初始质量浓度为100 mg/L、接种量为4%、pH 7、30 ℃条件下,接种后第6天,菌株J3对二氯喹啉酸的降解率可达到70%以上;在25 ℃、接种量为4%条件下,其生物修复作用可使受二氯喹啉酸(25%田间推荐剂量)药害盆栽烟草的恢复率达到69%。     

雷竹内生真菌分离及其功能性菌株筛选与鉴定

[目的]从雷竹根部分离其内生真菌并对其纤维素降解、植物病原菌抑制、铅的耐受能力等功能进行初步探究.[方法]采用组织块培养法分离内生真菌,刚果红平板培养基筛选纤维素降解菌,平板对峙法筛选植物病原拮抗菌.[结果]从雷竹根部共分离到35株内生真菌,其中具有纤维素降解功能的有7株;对油茶炭疽病原有抑制作用的有5株,对毛竹枯梢病原有抑制作用的有2株,对猕猴桃果腐病原有抑制作用的有2株;对铅具有强耐受性的有11株.利用形态特征和分子生物学方法对两株具有良好潜在应用价值的内生真菌LZ031、LZ033进行鉴定,分别为腐皮镰刀菌(Fusarium solani)和芦竹节菱孢(Arthrinium arundinis).[结论]雷竹根部具有丰富的内生真菌资源,且内生真菌功能多样,具有潜在的应用价值.     

白腐真菌降解农药研究进展

白腐真菌是一类腐生的丝状真菌,其分泌的非特异性胞外氧化酶可以降解多种结构不同、毒性较高且难以降解的有机农药。本研究总结了白腐真菌对有机氯、有机磷、氨基甲酸酯和拟除虫菊酯类农药的降解效果,并对部分农药的降解途径研究进展进行了综述,分析了白腐真菌降解农药的影响因素,同时对其应用前景进行了展望。     

土壤中降解涕灭威菌株的分离鉴定及降解特性

为探明土壤微生物对涕灭威的降解能力,用富集培养法分离驯化土壤中涕灭威的优势降解菌,初步筛选出了对涕灭威具有较高降解能力的菌株TB26和100-8。经过生理生化鉴定和16S rDNA序列同源性分析,将菌株TB26初步鉴定为克雷伯杆菌属(Klebsiella sp.),菌株100-8初步鉴定为枯草芽孢杆菌属(Bacillus sp.)。TB26和100-8生长的最适碳源分别为麦芽糖、D-果糖,最适氮源分别为蛋白胨、脲。基础无机盐培养基和缺氮培养基对两种菌的生长情况及降解率的影响不同,外加氮源能够提高100-8的降解率,而缺氮培养基中TB26的降解率较高。     

棉田甲胺磷农药残留的真菌降解研究

甲胺磷(Metham idopho,MAP)是一种水溶性的广谱杀虫、杀螨剂,化学名称为O,S-二甲基胺基硫代磷酸酯。该农药具有胃毒、触杀和内吸作用,其杀虫机理是抑制害虫体内的胆碱酯酶活性。人们在大量生产和使用其防治虫害的同时,也带来了负面影响[1],即造成土壤、水体污染,粮食、蔬菜作物     

咪唑乙烟酸降解菌的分离、鉴定及降解特性研究

采用高压富集方法,从生产咪唑乙烟酸农药厂排污口污泥中分离得到1株咪唑乙烟酸高效降解菌P14,根据菌株形态、生理生化特性及16S rDNA分析,鉴定该菌株为哈夫尼希瓦氏菌Shewanella hafniensis。初步研究了其在不同条件下对咪唑乙烟酸的降解性能。结果表明:在以咪唑乙烟酸为唯一碳源的无机盐培养基中,当咪唑乙烟酸初始质量浓度为100 mg/L、培养温度为30 ℃、pH值6.0、接种量7%时,菌株P14对咪唑乙烟酸的降解效果最佳,3 d内的降解率可达92%,因而可以此作为菌株P14降解咪唑乙烟酸的最佳条件。外加不同碳源时,P14菌株对咪唑乙烟酸的降解率呈现不同程度下降,其中柠檬酸钠对P14菌株降解效果影响较小。     

野燕麦病原真菌的分离及鉴定

为筛选出高效低毒的野燕麦(Avena fatua)生防菌,通过形态观察和rDNA-ITS序列对其病样中的菌株进行了鉴定。结果显示,从野燕麦病样中共分离出35个菌株,分别属于核腔菌属(Pyrenophora)、炭疽菌属(Colletotrichum)和附球菌属(Epicoccum)。发现三个属的菌落生长速率、形态各有特色。研究结果为筛选可用于防治野燕麦的生防菌奠定了基础。     

抗姜青枯菌银杏内生真菌的分离及抑菌特性

为了筛选新的生防菌种资源,从银杏根、叶中分离出对青枯劳尔氏菌Ralstonia solanacearum有拮抗作用的内生真菌,结合形态特征和ITS序列对该菌株进行了鉴定,分析了菌株发酵液的抑菌特性。结果表明,分离获得的80株内生真菌中有5株对青枯菌有拮抗作用,其中Gbh45具有良好的抑菌效果和遗传稳定性,根据形态特征和ITS序列比对,该菌株被鉴定为球黑孢菌Nigrospora sphaerica。该菌株的发酵产物经紫外照射、不同温度处理后其抑菌活性不发生变化,在碱性条件的耐受能力高于酸性,表明菌株Gbh45的发酵产物在自然条件下稳定性高,该菌对姜青枯病的生物防治具有巨大的应用潜力。     

Methyl parathion induced nephrotoxicity in male rats and protective role of vitamins C and E

Methyl parathion is an organophosphate insecticide that has been used in agriculture and domestic for several years. Vitamin C (200 mg/kg bw per day) + vitamin E (200 mg/kg bw per day), methyl parathion (0.28 mg/kg bw per day) and vitamin C (200 mg/kg bw per day) + vitamin E (200 mg/kg bw per day) + methyl parathion (0.28 mg/kg bw per day) combination were given to rats orally via gavage for 7 weeks. Body and kidney weights, malondialdehyde (MDA) levels and histopathological changes were investigated at the end of 4th and 7th weeks comparatively with control group. When methyl parathion-treated group and vitamins C and E + methyl parathion-treated group were compared to control group body and kidney weights decreased significantly at the end of 4th and 7th weeks. MDA levels increased in kidney tissues of the methyl parathion- and vitamins C and E + methyl parathion-treated groups compared to control group. MDA levels decreased significantly in vitamins C and E + methyl parathion treated group compared with methyl parathion treated group at the end of 4th and 7th weeks. In our light microscopic investigations, after 4 weeks of methyl parathion exposure, glomerular atrophy and vascular dilatation, and after 7 weeks, necrosis and edema were observed in the kidney tissues. After 4 weeks of vitamins C and E + methyl parathion exposure, mononuclear cell infiltrations, and after 7 weeks, calcification were detected in the kidney tissues.     

Degradation Studies of the Non-lethal Bird Repellent,Methyl Anthranilate

Methyl anthranilate (MA), a food grade flavor and fragrance additive, has been reported to be an effective non-lethal bird repellent in a variety of situations. Despite the experimental success of MA, field studies have yielded widely differing levels of efficacy. Diminished efficacy in some field trials probably results from the failure of specific formulations to retain or protect the active ingredient under natural conditions. Therefore, a clearer understanding of the physical and chemical factors affecting the stability of MA is needed. We undertook a series of laboratory studies on hydrolysis, photolysis and microbial degradation of MA, the results of which could be useful in the development of appropriate formulation strategies and residue analyses. We found the n-octanol:water partition coefficient, (P) to be 84. MA is not subject to hydrolysis at 25°C in phosphate buffer media at pH 5·0, 7·0 and 9·0. MA slowly photodegrades under simulated UV ‘sunlight’. Forty-four percent of MA is lost after 432 h illuminance at 1·25 mW cm⁻², which is equivalent to approximately 1200 h natural sunlight (40°N, noontime, June). Kinetic data indicate that the initial step of photolysis, subsequent to excitation, is a second-order reaction with respect to MA. A major photodegradation product appeared in an amount of about 10% of the mass balance and was determined to be an oxidized trimer of MA. MA is primarily affected by aerobic microbial degradation. For a 12:12 h light:dark, under laboratory illumination, 12% of water-solubilized material can be lost in the first seven days. Losses were 30% and 42% at 16 and 27 days, respectively. Under conditions of optimal bacterial growth (warmth and darkness) loss of MA was 22% at nine days and 100% by 20 days. The susceptibility of MA to microbial degradation is promising for the prospects of developing formulated, environmentally safe, bird repellents.     

Comparative studies on chlorpyrifos and methyl parathion induced oxidative stress in different parts of rat brain: Attenuation by antioxidant vitamins

Organophosphate (OP) pesticides are among the most widely used synthetic chemicals for controlling a wide variety of pests. Chlorpyrifos (o,o′-diethyl-o-3,5,6-trichloro-2-pyridyl phosphorothionate, CPF) is among the leading OP pesticides used extensively throughout the world including India while methyl parathion (o,o-di methyl-o-p-nitrophenyl phosphorothioate, MPT) another OP compound, widely used as insecticide and acaricide to control many biting or sucking pests of agricultural crops. Present study was carried out to compare the chronic toxicity of CPF and MPT, their potential to generate oxidative stress and ameliorating effects of antioxidant vitamins in brain of rats. Results of the present study clearly demonstrated that the oral exposure of CPF or MPT, generated oxidative stress in different parts of rat brain consequently accumulating malondialdehyde (MDA) and 4-hydroxynonanal (4HNE), the two major end products of lipid peroxidation, in all the three brain regions i.e. fore-, mid- and hind-brain. The levels of hydrogen peroxide (H₂O₂) were also increased in all the three brain regions when compared with control. CPF and MPT exposure caused decrease in the levels of reduced glutathione (GSH) and increase in the levels of oxidized glutathione (GSSG) in all the three brain regions. The increase in the levels of MDA, 4HNE, H₂O₂ and GSSG was less pronounced when CPF or MPT was given to the rats fed with a mixture of vitamin A, E and C. The present findings clearly show that oral intake of a mixture of vitamin A, E and C protects the rats from MPT or CPF induced oxidative stress and suggest that this treatment alleviates the toxicity of these pesticides to a greater extent.     

单嘧磺隆在土壤中的残留分析和消解动态研究

研究了新磺酰脲除草剂单嘧磺隆在土壤中的残留分析方法及其土壤消解动态和最终残留。土壤经甲醇和稀氨水混合液提取 ,液液分配及 C18净化 ,浓缩后用带紫外检测器的高效液相色谱仪进行测定。单嘧磺隆的最低检出量为 4 ng,在土壤中的最低检出浓度为0 .0 2 mg/ kg。本方法的添加回收率为 95.10 %～ 10 3.77% ,变异系数为 1.4 7%～ 11.80 % ,符合农药残留分析的要求。运用上述方法 ,测定了单嘧磺隆在北京和山东土壤中的消解动态以及最终残留。结果表明 :单嘧磺隆在土壤中消解的速度较慢 ,在北京土壤中的半衰期为 9.2 4 d,山东土壤中的半衰期为 13.59d。按推荐剂量施药 ,小麦收获时 ,在北京和山东两地土壤中均未检出单嘧磺隆。     

环境条件对除草剂莎稗磷降解的影响

环境条件影响莎稗磷在土壤中的降解速度 :随着土壤温度的升高和含水量的增加 ,莎稗磷降解速度加快 ,在温度为 2 0、30和 4 0℃下 ,经过 10 d,莎稗磷的降解率分别为10 .4 %、2 6 .7%和 37.6 % ;在相对含水量为 30 %～ 110 %的土壤中 ,15d后莎稗磷降解 4 5.0 %～ 6 8.4 %。土壤中有机质能促进莎稗磷的降解 ,在有机质含量为 3.35%和 0 .55%的两种土壤中 ,莎稗磷的半衰期分别为 11d和 15d。莎稗磷在碱性土壤中比在酸性土壤中降解快 ,在偏酸性 (p H值为 6 .0 1)土壤中的半衰期为 2 2 d,在偏碱性 (p H值为 7.98)土壤中半衰期为 15d.     

Enhanced Degradation of the Fungicide Vinclozolin: Isolation and Characterisation of a Responsible Organism

Enhanced degradation of the fungicide vinclozolin was stimulated by multiple successive applications to a soil without any history of previous pesticide input. A vinclozolin-degrading bacterium isolated from this soil was identified as a strain of Pseudomonas putida. This organism metabolised vinclozolin as a source of carbon, but it would neither grow with nor transform any other closely related dicarboximide fungicides nor the degradation product, 3,5-DCA. The degradation of vinclozolin by cultures of P. putida St-1 was investigated under various culture conditions; biodegradation was optimal at 23°C, pH 6·5 and inoculum densities of 10⁷ cells ml⁻¹ but cultures would grow from as little as 100 cells ml⁻¹. Amendments of the vinclozolin-degrading isolate to soil previously untreated with the fungicide caused rapid degradation of applied vinclozolin, whereas amendments of boiled cells, or viable cells grown in the absence of vinclozolin, produced no discernible effect on the rate of vinclozolin degradation.     

Acute effects of methyl parathion and diazinon as inducers for oxidative stress on certain biomarkers in various tissues of rainbowtrout (Oncorhynchus mykiss)

Present study aimed mainly to assess oxidative stress pesticides such as methyl parathion (MP) and diazinon, which are widely used insecticides and contaminate aquatic ecosystems, on certain biomarkers in various tissues of rainbowtrout (Oncorhynchcus mykiss). Biomarkers selected for stress monitoring were malondialdehyde (MDA) and antioxidant defense system (ADS) mainly reduced glutathione (GSH), glutathione reductase (GR), peroxidase (GSH-PX), transferase (GST) and superoxidedismutase (SOD) activities in the liver, gills and muscle of fishes exposed to 0.5 and 1 ppm dosages of MP and diazinon for 24, 48 and 72 h. According to these results, after the administrations of MP and diazinon promote MDA content in some of the tissues of fishes treated with both dosages of MP and diazinon. With regard to the ADS, GSH-Px, GST, SOD, GR activities and GSH levels fluctuated after 24, 48 and 72 h in all the treatment groups compared with controls. Collective results demonstrated that exposure of fish to pesticides induced an increase in MDA joined with fluctuated ADS. This may reflect the potential role of these parameters as useful biomarkers for assessment of water pollution.     

丙硫克百威及其主要代谢物在棉田中的残留降解研究

将20% 丙硫克百威乳油施于棉田, 采用气相色谱分析技术研究了丙硫克百威及其主要代谢产物在棉田中的残留降解情况。结果表明: 1) 丙硫克百威在棉田土壤和棉叶中可很快降解转化为克百威, 克百威在棉叶中的最大残留值出现在施药后当天, 在棉田土壤中出现在施药后3d, 说明丙硫克百威在棉叶中的降解速率快于在棉田土壤中; 2) 克百威可进一步转化为3-羟基克百威, 后者在棉叶和棉田土壤中的残留量表现为先升后降, 到第10 天才达最大值,明显滞后于克百威最大值出现的时间; 3) 丙硫克百威和克百威在棉叶和棉田土壤中的降解过程符合Ct= C0·e-kt方程, 它们在棉叶中的降解半衰期为3.6～4.4d, 在棉田土壤中则为10.4～11.9d; 4) 当丙硫克百威的用量按有效成份计为200～400g/hm2, 每季棉花施药3～4 次(每次间隔7d) , 最后一次施药距采收时间分别为20、30d时, 丙硫克百威(含克百威和3-羟基克百威) 在棉籽和棉田耕层土壤中的残留量均小于0. 5 mg/kg。     

Acute, subacute and subchronic administration of methyl parathion-induced testicular damage in male rats and protective role of vitamins C and E

Methyl parathion is an organophosphate insecticide that has been used in agriculture and domestic for several years. Vitamin C (200 mg/kg bw per day) + vitamin E (200 mg/kg bw per day), methyl parathion (0.28 mg/kg bw per day) and vitamin C (200 mg/kg bw per day) + vitamin E (200 mg/kg bw per day) + methyl parathion (0.28 mg/kg bw per day) combination were given to rats orally via gavage for 7 weeks. Body and testis weights, sperm counts, sperm motility, sperm morphology and histopathological changes in the testes were investigated at the end of 24 h, 4th and 7th weeks comparatively with control group. No pathological changes were observed in all parameters at the end of 24 h. When methyl parathion-treated group and vitamins C and E + methyl parathion-treated group were compared to control group, body and testis weights decreased significantly at the end of 4th and 7th weeks. It was observed that, at the end of 4th and 7th weeks there was a statistically significant decrease in sperm counts and sperm motility, increase in abnormal sperm morphology when methyl parathion- and vitamins C and E + methyl parathion-treated group were compared to control group. While sperm counts increased at the end of 4th and 7th weeks, sperm motility increased at the end of 7th week when vitamins C and E + methyl parathion-treated group compared with methyl parathion-treated group, no changes were observed in abnormal sperm morphology at the end of 4th and 7th weeks. In our light microscopic investigations, after 4 and 7 weeks of methyl parathion exposure, necrosis and edema were observed in the seminiferous tubules and interstitial tissues. After 4 and 7 weeks of vitamins C and E + methyl parathion exposure, degenerative changes were detected in the seminiferous tubules while no pathological findings were observed in the interstitial tissues. According to the present study, we conclude that vitamins C and E reduces methyl parathion testicular toxicity, but it does not protect completely.