一株产嗜铁素耐镉菌的分离及其对黑麦草种子萌发的作用

Isolation of a siderophore-producing and cadmium-resistant bacteria and its effect on seed germination of ryegrass

摘要:

【背景】产嗜铁素细菌(Siderophore-Producing bacteria，SPB)是一类耐重金属性能较好的促生微生物，将其应用于土壤重金属污染修复方面的研究已成为该领域的研究热点。【目标】为重金属镉污染土壤修复提供种质资源，并探究产嗜铁素细菌对Cd2+胁迫下黑麦草种子萌发的影响。【方法】采用微生物分离纯化技术，从甘肃省临泽县宏鑫矿业尾矿区采集土壤样品，分离筛选出一株能够产嗜铁素且耐镉胁迫的菌株，采用16s rRNA基因序列鉴定该菌株，并测定其嗜铁素螯合基团结构类型及生长和产嗜铁素曲线，对菌株嗜铁素分离纯化后测定其荧光强度并进行紫外光谱扫描，最后探究嗜铁素及其产生菌对Cd2+胁迫下黑麦草种子萌发的影响。【结果】经鉴定该菌为假单胞菌属(Pseudomonas sp. W-STS-8)，能产生一种黄绿色嗜铁素——脓菌素(Pyoverdine)，该嗜铁素同时具有异羟肟酸型和儿茶酚型2种螯合结构；其嗜铁素产量在菌株生长稳定期的后期达到最大值(68%)，而且嗜铁素产量与菌株生物量呈正相关。嗜铁素经分离纯化后，在紫外灯(254 nm)下可见荧光，在400 nm处具有紫外光谱特征吸收峰。该菌及其嗜铁素对Cd2+胁迫下黑麦草种子萌发实验结果表明，与对照相比，经W-STS-8菌悬液和嗜铁素处理后黑麦草种子发芽率显著上升，分别提高了73.14%和150.92%。【结论】对该菌株的深入研究，可为重金属镉污染土壤的微生物-植物联合修复的生态修复工程提供种质资源和科学基础。

Abstract:

[Background] Siderophore-producing bacteria (SPB) is a kind of growth-promoting microorganism with high heavy metal resistance, and its application in soil remediation of heavy metal contaminated soil has attracted increasingly attentions. [Objective] To provide organism resources for remediation of heavy metal cadmium contaminated soil; To investigate the effect of SPB on seed germination of ryegrass under cadmium stress. [Methods] the soil that isolated the bacteria was collected from Hongxin Mining Area, Linze county, Gansu province, a bacteria is capable of both producing siderophore and cadmium-resistant was obtained by isolating and purificating of microorganisms technology, and the identifying of this strain was used 16s rRNA gene sequence, and the structure type of chelating groups of siderophore, the growth curve and siderophore production curve of the strain were measured, the fluorescence intensity and ultraviolet spectrum of the siderophore were determinated after separating and purificating from the culture of this bacterium. Finally, the effects of siderophore and its producing bacteria on the germination of ryegrass under cadmium stress were investigated. [Results] The bacteria was identified as Pseudomonas sp. W-STS-8 and it could secrete a yellow-green siderophore—pyoverdine, which has two types chelating groups structures, hydroxamates type and catecholates type. The yield of siderophore reached its maximum value (68%) at the late of the stationary phase, and the yield of siderophore was positively correlated with the biomass of the strain. After separating and purificating of siderophore, the fluorescence could be observed under UV light (254 nm), and the characteristic absorption peak of ultraviolet spectrum was at 400 nm. By studying the effects of siderophore and its producing bacteria on the germination of ryegrass under cadmium stress, the result showed that compared with the control group, the strain culture and its siderophore showed remarkable effect, the seed germination rate of ryegrass increased by 73.14% and 150.92%, respectively. [Conclusion] This strain is expected to provide microbes resources and scientific basis for ecological remediation project by further study, which related to microbial-plant combined remediation of soil contaminated by cadmium.