本文選題：麥草畏　切入點(diǎn)：微生物降解　出處：《南京農(nóng)業(yè)大學(xué)》2015年碩士論文

【摘要】：麥草畏在我國(guó)被廣泛的運(yùn)用在農(nóng)業(yè)除草方面,它主要被作為出苗后除草劑使用,用來(lái)防治多年生闊葉雜草和禾本科雜草。因?yàn)樗慕Y(jié)構(gòu)較為穩(wěn)定和過(guò)度的使用,導(dǎo)致它在土壤中的殘留十分嚴(yán)重,所以越來(lái)越多人開(kāi)始研究麥草畏在土壤中的降解問(wèn)題。國(guó)外已經(jīng)有能降解麥草畏的菌株被分離得到的報(bào)道,也有相關(guān)降解途徑和基因的報(bào)道,但在國(guó)內(nèi)研究的比較少。本研究從麥草畏降解菌株的分離與篩選開(kāi)始,進(jìn)而研究其理化特性及降解特性、推測(cè)相關(guān)的降解途徑并且克隆降解的基因。利用麥草畏為唯一碳源,利用富集馴化技術(shù)從農(nóng)藥廠廢水生化處理污泥中分離到具有麥草畏降解能力的菌株,命名為SC-1,根據(jù)它的培養(yǎng)特征、生理生化特征和16s rDNA分析可以將其初步鑒定為鞘酯菌屬。該菌對(duì)麥草畏的降解效率可達(dá)到90%,它的最適生長(zhǎng)溫度為30℃,最適的pH為7.0左右,不耐鹽;對(duì)于無(wú)機(jī)氮源的利用率較低,而對(duì)葡萄糖、麥芽糖和糊精等糖源的利用率卻比較高。SC-1可以為麥草畏為唯一的的碳源生長(zhǎng),且在36 h內(nèi)幾乎可以將1g/L的麥草畏降解完全,在溫度為30℃、Na+濃度為10 g/L、pH為7左右時(shí),菌株的降解效率較好。其降解時(shí)的最佳環(huán)境與SC-1生長(zhǎng)所需要的環(huán)境很相似,同樣也是在接種量和通氣量較大的情況下降解的效果比較好。當(dāng)麥草畏的濃度低于1000mg/L時(shí),SC-1的對(duì)其的降解效率都比較好,當(dāng)麥草畏濃度高于1000mg/L后,會(huì)對(duì)SC-1產(chǎn)生毒性,SC-1不但無(wú)法降解麥草畏甚至無(wú)法生長(zhǎng)。利用液相色譜和質(zhì)譜對(duì)SC-1降解麥草畏的中間產(chǎn)物檢測(cè)結(jié)果表明,該菌降解麥草畏的第一步為脫甲基生成沒(méi)有除草劑活性的中間產(chǎn)物3,6-DCSA(3,6--二氯水楊酸)。將麥草畏降解為DCSA的這一步中起關(guān)鍵作用的基因是DMO基因,該基因主要調(diào)控麥草畏的O-型脫甲基酶合成,該酶主要有還原酶、鐵氧化還原蛋白和加氧酶組成。此酶系統(tǒng)主要用作于電子傳遞鏈,在電子傳遞鏈中NADH(煙酰胺的還原形式腺嘌呤二核苷酸)穿梭通過(guò)一個(gè)還原酶到鐵氧還蛋白。國(guó)外對(duì)此的研究比較多,關(guān)于DMO的報(bào)道也比較的多,所以有關(guān)DMO的基因序列已經(jīng)報(bào)道過(guò)了,根據(jù)已經(jīng)報(bào)道的基因序列設(shè)計(jì)引物后,將SC-1的DNA作為模板擴(kuò)增后進(jìn)行測(cè)序,發(fā)現(xiàn)其序列與已報(bào)道的相同,所以基本可以確定SC-1對(duì)麥草畏的降解途徑與已報(bào)道的完全相同。
[Abstract]:Wheat straw forceps are widely used in agricultural herbicides in China. They are mainly used as herbicides after emergence to control perennial broadleaved weeds and gramineous weeds because of their stable structure and excessive use. As a result of its very serious residue in the soil, more and more people began to study the degradation of wheat straw forceps in the soil. There have been reports of the isolation of strains that can degrade the forbidding wheat straw, as well as related degradation pathways and genes. But there are few studies in our country. This study began with the isolation and screening of strains of wheat straw forvos degradation, and then studied its physical and chemical properties and degradation characteristics, speculated the related degradation pathway and cloned the degradation gene. By means of enrichment and acclimation, a strain with biodegradable ability of wheat straw was isolated from the sludge of biochemical treatment of agricultural pharmaceutical plant wastewater, named SC-1, according to its culture characteristics, Physiological and biochemical characteristics and 16s rDNA analysis showed that the strain could be identified as sphingomycetes. The biodegradation efficiency of the strain could reach 90%, the optimum growth temperature was 30 鈩，

本文編號(hào)：1672982