【摘要】：桃樹(Prunus persica)連作障礙是一個(gè)世界性的難題,越來越多的研究表明,桃樹連作障礙與其根系分泌的自毒物質(zhì)密切相關(guān)。本實(shí)驗(yàn)室已從9年生桃樹根際土壤中分離出了主要自毒物質(zhì)苯甲酸降解菌,本研究以其中的乙酸鈣不動(dòng)桿菌(Acinetobacter calcoaceticu)WH-B2為研究對(duì)象,對(duì)其外觀形態(tài)、生長(zhǎng)和降解特性進(jìn)行分析,并對(duì)該菌株的最適生長(zhǎng)和降解條件進(jìn)行篩選;同時(shí)還對(duì)自毒物質(zhì)苯甲酸的降解產(chǎn)物進(jìn)行了毒性測(cè)定,并初步探討了乙酸鈣不動(dòng)桿菌WH-B2苯甲酸降解基因的定位,以期為乙酸鈣不動(dòng)桿菌WH-B2在緩解連作障礙中的應(yīng)用以及為后續(xù)研究質(zhì)粒轉(zhuǎn)化及工程菌的研制提供理論依據(jù)。試驗(yàn)主要結(jié)果如下:1.乙酸鈣不動(dòng)桿菌WH-B2能以苯甲酸作為碳源進(jìn)行生長(zhǎng)繁殖,并且在不同的培養(yǎng)條件下達(dá)到最大生長(zhǎng)量的時(shí)間不同。在液體培養(yǎng)條件下,該菌株自接種后16 h即可達(dá)到最大生長(zhǎng)量,此時(shí)培養(yǎng)基中的苯甲酸含量最低;在土壤培養(yǎng)條件下,菌株在接種后的24 h達(dá)到最大生長(zhǎng)量,同時(shí)土壤中的苯甲酸含量最低。2.乙酸鈣不動(dòng)桿菌WH-B2的生長(zhǎng)和降解能力在不同的外界條件下表現(xiàn)出明顯的差異。菌株在底物濃度為300 mg/L,溫度為30℃,pH=7時(shí)表現(xiàn)出最佳生長(zhǎng)和降解能力。在苯甲酸存在的前提下,加入適量的葡萄糖和蛋白胨等碳源添加物后,能夠促進(jìn)菌株的生長(zhǎng)以及苯甲酸的降解。3.利用化感模式植物萵苣種子的萌發(fā)試驗(yàn)對(duì)苯甲酸的降解產(chǎn)物進(jìn)行了毒性測(cè)定,結(jié)果表明,沒有接種菌株且含有苯甲酸的培養(yǎng)基處理的萵苣種子發(fā)芽率、發(fā)芽勢(shì)、發(fā)芽指數(shù)和活力指數(shù)均接近于0。降解產(chǎn)物處理組和蒸餾水對(duì)照組在各個(gè)指標(biāo)上沒有明顯差異,但是均顯著高于沒有接種菌株的處理組。4.通過質(zhì)粒檢測(cè)和質(zhì)粒消除對(duì)乙酸鈣不動(dòng)桿菌WH-B2菌株降解基因進(jìn)行了初步定位,結(jié)果表明,該菌株含有質(zhì)粒,并且該質(zhì)粒上含有控制降解苯甲酸的基因。
[Abstract]:(Prunus persica) continuous cropping disorder in peach trees is a worldwide problem. More and more studies have shown that the continuous cropping disturbance is closely related to the autotoxic substances secreted by the root system of peach trees. Benzoic acid degrading bacteria were isolated from rhizosphere soil of 9-year-old peach trees. In this study, Acinetobacter calcometrate (Acinetobacter calcoaceticu) WH-B2) was used as the research object, and the appearance and morphology of the bacteria were studied. The growth and degradation characteristics of the strain were analyzed, and the optimum growth and degradation conditions of the strain were screened. At the same time, the toxicity of the degradation products of benzoic acid, an autotoxic substance, was also determined, and the localization of benzoic acid degradation gene of Acinetobacter calcometrate WH-B2 was also discussed. In order to provide a theoretical basis for the application of Acinetobacter calcometrate WH-B2 in the alleviation of continuous cropping obstacles and for the subsequent study of plasmid transformation and the development of engineering bacteria. The main results of the test are as follows: 1. Acinetobacter calcinoacetate WH-B2 could grow and reproduce with benzoic acid as carbon source, and the time of maximum growth was different under different culture conditions. Under the condition of liquid culture, the strain could reach the maximum growth rate 16 hours after inoculation, and the content of benzoic acid in the medium was the lowest. Under the condition of soil culture, the strain reached the maximum growth at 24 h after inoculation, and the content of benzoic acid in soil was the lowest. 2. The growth and degradation ability of Acinetobacter calcinoacetate WH-B2 were significantly different under different external conditions. When the substrate concentration was 300 mg/L, and the temperature was 30 鈩，

本文編號(hào)：2439593