复合功能菌群的构建及其对铅锌胁迫下蓖麻种子萌发的影响

发布时间：2018-11-03 12:41

【摘要】：油料植物蓖麻(Ricinus communist L.)有着良好的适应性、重金属耐性及高产油率,可应用于重金属污染的植物修复。而利用蓖麻进行修复时,高浓度的重金属离子会破坏植物的正常代谢,限制种子萌发,从而对其生长生存和修复效果造成严重影响。针对以上情况,本文以蓖麻为供试植物,并不同于以往大都采用单一微生物进行联合修复的传统方法,构建了复合菌群,研究了微生物菌群对重金属胁迫下蓖麻种子萌发的影响,论文取得的主要研究结果如下:(1)涂布初筛后,共从课题组内经菌肥改良后的向日葵、辣椒根际土壤中分离出真菌10株,细菌24株,选取形态稳定、长势良好的7株微生物以促生性能为指标进行复筛,初步确定L6、L7、Lll、L14与X85株菌株具备良好的促生性能,可作为构建复合菌群的可选根际促生菌。(2)以耐性菌为基础,研究铅锌胁迫下复合菌群对蓖麻种子萌发的影响。对课题组前期研究的三株耐性真菌HA、WB、J3,通过正交实验,考查其不同组合对铅锌的吸附性能。结果显示,HA与J3混合培养(X2)在最适条件下,对铅离子的去除率可达91.3%,对锌离子的去除率可达51.4%,高于其他组合,能满足复合菌群对铅锌胁迫的耐性需求,因而可以将HA、J3作为构建复合功能菌群的固定菌株。根据课题组已有研究,耐性真菌HA为米曲霉(Aspergillus oryzae),耐性真菌J3为虫生轮殖孢(Verticillium insectorum)。(3)对筛选出的根际促生菌与耐性真菌进行平板对峙实验,结果表明,复筛出的5株微生物仅L6、L11与HA之间有一定的拮抗作用,结合促生性能,优选X8、L14作为构建符合菌群的根际促生菌,并进行测序鉴定。根据测序结果构建系统发育树,进行BLAST比对后最终确定L14为尖孢镰刀菌(Fusarium oxysporum),而X8 为枯草芽孢杆菌(Bacillus subtilis)。(4)通过沙培实验,考察微生物菌群对重金属胁迫下蓖麻种子萌发的影响,包括接种复合菌群对蓖麻生物量、重金属富集及根系生长等情况的影响,探讨其对蓖麻种子萌发及幼苗生长的作用并优选出最适菌群。结果表明,复合菌群的添加可以有效促进植物对重金属的富集,其中,D1菌群(HA、J3、L14)在200mg/L条件下对Pb的累积量提升达到37.1%,在400mg/L条件下对Zn的累积量提升达到26.9%;D2(HA、J3、X8)菌群在600mg/L条件下对Pb的累积量提升达到29.3%,在400mg/L条件下对Zn的累积量提升达到41.6%。综合对比复合菌群D1与D2的各项生长指标、根系形态及重金属富集量,优选出复合功能菌群D2为最优菌群,可作为下一步盆栽实验的复合功能菌群。最终结果表明,该菌群可以有效促进铅锌胁迫下蓖麻种子的萌发。
[Abstract]:Oil plant castor (Ricinus communist L.) It has good adaptability, heavy metal tolerance and high oil yield, and can be used in phytoremediation of heavy metal pollution. However, high concentration of heavy metal ions will destroy the normal metabolism of plants and restrict the seed germination, which will seriously affect the growth, survival and repair effect of castor. In view of the above situation, the compound flora was constructed by using castor as the tested plant, which was different from the traditional method in which single microorganism was used to repair the plant in the past. The effects of microbial flora on the germination of castor seeds under heavy metal stress were studied. The main results were as follows: (1) after primary screening, sunflower was improved by bacterial fertilizer. 10 strains of fungi and 24 strains of bacteria were isolated from rhizosphere soil of capsicum. 7 strains of microbes with stable morphology and good growth were selected and screened for promoting growth ability. It was preliminarily confirmed that L6, L7, LlllL14 and X85 strains had good growth promoting performance. (2) on the basis of tolerant bacteria, the effect of compound flora on seed germination of castor under lead and zinc stress was studied. The adsorption properties of three resistant fungi HA,WB,J3, for lead and zinc were studied by orthogonal experiment. The results showed that under the optimum conditions, the removal rate of lead ion and zinc ion in HA and J3 mixed culture (X2) was 91.3 and 51.4, which was higher than that in other combinations. Therefore, HA,J3 can be used as a fixed strain to construct complex functional flora. According to the previous research, the resistant fungus HA is (Aspergillus oryzae), resistant fungus J3 is (Verticillium insectorum). (3. The results show that the isolated rhizosphere probiotic fungi and tolerant fungi are confronted with each other. Only 5 strains of microorganism L6, L11 and HA had antagonistic effect. Combined with the growth promoting ability, X8G L14 was selected as the rhizosphere promoting bacteria which was in accordance with the bacterial flora, and identified by sequencing. The phylogenetic tree was constructed according to the sequencing results. After BLAST comparison, it was determined that L14 was (Fusarium oxysporum), and X8 was (Bacillus subtilis). (4 (Bacillus subtilis). The effects of microbial flora on the germination of castor seeds under heavy metal stress were investigated, including the effects of inoculation on ricin biomass, accumulation of heavy metals and root growth. To study the effect of castor on seed germination and seedling growth and to select the optimal flora. The results showed that the addition of complex flora could effectively promote the accumulation of heavy metals in plants. Among them, the accumulation of Pb by D1 microflora (HA,J3,L14) reached 37.1g under 200mg/L condition. Under the condition of 400mg/L, the cumulative amount of Zn increased to 26.9%. The cumulative amount of D2 (HA,J3,X8) to Pb increased to 29.3 under 600mg/L and 41.6 to Zn under 400mg/L. By comparing the growth indexes, root morphology and heavy metal accumulation of the complex bacteria D 1 and D 2, the composite functional bacteria D 2 was selected as the optimal flora, which could be used as the next step in the pot experiment. The results showed that the microflora could effectively promote the germination of castor seeds under lead and zinc stress.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S565.6;X17

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