Liu Wuxing, Wang Beibei, Wang Qingling, Hou Jinyu, Wu Longhua, Wood Jennifer L, Luo Yongming, Franks Ashley E
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Sci Pollut Res Int. 2016 Sep;23(18):18621-9. doi: 10.1007/s11356-016-7041-2. Epub 2016 Jun 15.
Plant growth-promoting yeasts are often over looked as a mechanism to improve phytoremediation of heavy metals. In this study, Cryptococcus sp. NSE1, a Cd-tolerant yeast with plant growth capabilities, was isolated from the rhizosphere of the heavy metal hyperaccumulator Sedum plumbizincicola. The yeast exhibited strong tolerance to a range of heavy metals including Cd, Cu, and Zn on plate assays. The adsorption rate Cd, Cu, Zn by NSE1 was 26.1, 13.2, and 25.2 %, respectively. Irregular spines were formed on the surface of NSE1 when grown in MSM medium supplemented with 200 mg L(-1) Cd. NSE1 was capable of utilizing 1-aminocyclopropane-1-carboxylate (ACC) as a sole nitrogen source and was capable of solubilization of inorganic phosphate at rates of 195.2 mg L(-1). Field experiments demonstrated that NSE1 increased phytoremediation by increasing the biomass of Cd hyperaccumulator S. plumbizincicola (46 %, p < 0.05) during phytoremediation. Overall, Cd accumulation by S. plumbizincicola was increased from 19.6 to 31.1 mg m(-2) though no difference in the concentration of Cd in the shoot biomass was observed between NSE1 and control. A Cd accumulation ratio of 38.0 % for NSE1 and 17.2 % for control was observed. The HCl-extractable Cd and CaCl2-extractable Cd concentration in the soil of the NSE1 treatment were reduced by 39.2 and 29.5 %, respectively. Community-level physiology profiling, assessed using Biolog Eco plates, indicated functional changes to the rhizosphere community inoculated with NSE1 by average well color development (AWCD) and measurement of richness (diversity). Values of Shannon-Weiner index, Simpson index, and McIntosh index showed a slight but no significant increases. These results indicate that inoculation of NSE1 could increase the shoot biomass of S. plumbizincicola, enhance the Cd accumulation in S. plumbizincicola, and decrease the available heavy metal content in soils significantly without overall significant changes to the microbial community.
促进植物生长的酵母通常被忽视作为一种改善重金属植物修复的机制。在本研究中，从重金属超富集植物东南景天的根际分离出一株具有植物生长能力且耐镉的酵母隐球菌属NSE1。在平板试验中，该酵母对包括镉、铜和锌在内的多种重金属表现出较强的耐受性。NSE1对镉、铜、锌的吸附率分别为26.1%、13.2%和25.2%。当在添加200mg L(-1)镉的MSM培养基中生长时，NSE1表面形成不规则的刺。NSE1能够利用1-氨基环丙烷-1-羧酸（ACC）作为唯一氮源，并且能够以195.2mg L(-1)的速率溶解无机磷酸盐。田间试验表明，在植物修复过程中，NSE1通过增加镉超富集植物东南景天的生物量（46%，p<0.05）来提高植物修复效果。总体而言，东南景天的镉积累量从19.6mg m(-2)增加到31.1mg m(-2)，尽管在地上部生物量中的镉浓度在NSE1和对照之间未观察到差异。观察到NSE1的镉积累率为38.0%，对照为17.2%。NSE1处理土壤中HCl可提取镉和CaCl2可提取镉的浓度分别降低了39.2%和29.5%。使用Biolog Eco平板评估的群落水平生理图谱表明，通过平均孔颜色发展（AWCD）和丰富度（多样性）测量，接种NSE1的根际群落功能发生了变化。香农-韦纳指数、辛普森指数和麦金托什指数的值略有增加，但无显著差异。这些结果表明，接种NSE1可以增加东南景天的地上部生物量，增强东南景天对镉的积累，并显著降低土壤中有效重金属含量，而不会对微生物群落产生总体显著变化。
