Ma Ying, Rajkumar Mani, Freitas Helena
Centre for Functional Ecology, Department of Botany, University of Coimbra, Coimbra 3000, Portugal.
J Hazard Mater. 2009 Jul 30;166(2-3):1154-61. doi: 10.1016/j.jhazmat.2008.12.018. Epub 2008 Dec 7.
In this study, among a collection of Ni-resistant bacterial strains isolated from the rhizosphere of Alyssum serpyllifolium and Phleum phleoides grown on serpentine soil, five plant growth-promoting bacteria (PGPB) were selected based on their ability to utilize 1-aminocyclopropane-1-carboxylate (ACC) as the sole N source and promote seedling growth. All of the strains tested positive for indole-3-acetic acid (IAA) production and phosphate solubilization. In addition, four of the strains exhibited significant levels of siderophores production. Further, the efficiency of PGPB in enhancing Ni solubilization in soils was analyzed. Compared with control treatment, inoculation of PGPB strains significantly increased the concentrations of bioavailable Ni. Furthermore, a pot experiment was conducted to elucidate the effects of inoculating Ni-resistant PGPB on the plant growth and the uptake of Ni by Brassica juncea and B. oxyrrhina in soil contaminated with 450 mg kg(-1) Ni. Psychrobacter sp. SRA2 significantly increased the fresh (351%) and dry biomass (285%) of the B. juncea test plants (p<0.05), whereas Psychrobacter sp. SRA1 and Bacillus cereus SRA10 significantly increased the accumulation of Ni in the root and shoot tissues of B. juncea compared with non-inoculated controls. This result indicates that the strains SRA1 and SRA10 facilitated the release of Ni from the non-soluble phases in the soil, thus enhancing the availability of Ni to plants. A significant increase, greater than that of the control, was also noted for growth parameters of the B. oxyrrhina test plants when the seeds were treated with strain SRA2. This effect can be attributed to the utilization of ACC, solubilization of phosphate and production of IAA. The results of the study revealed that the inoculation of Ni mobilizing strains Psychrobacter sp. SRA1 and B. cereus SRA10 increases the efficiency of phytoextraction directly by enhancing the metal accumulation in plant tissues and the efficient PGPB, Psychrobacter sp. SRA2 increases indirectly by promoting the growth of B. juncea and B. oxyrrhina.
在本研究中，从生长在蛇纹石土壤上的匍匐庭荠和梯牧草根际分离得到一批耐镍细菌菌株，基于它们利用1-氨基环丙烷-1-羧酸（ACC）作为唯一氮源以及促进幼苗生长的能力，从中筛选出5株植物促生细菌（PGPB）。所有测试菌株的吲哚-3-乙酸（IAA）产生和磷溶解试验均呈阳性。此外，其中4株菌株表现出显著水平的铁载体产生。进一步分析了PGPB提高土壤中镍溶解性的效率。与对照处理相比，接种PGPB菌株显著提高了生物可利用镍的浓度。此外，进行了盆栽试验，以阐明接种耐镍PGPB对土壤中镍含量为450 mg kg(-1)的芥菜和少花龙葵的植物生长及镍吸收的影响。嗜冷杆菌属菌株SRA2显著增加了芥菜受试植物的鲜重（351%）和干重（285%）（p<0.05），而嗜冷杆菌属菌株SRA1和蜡样芽孢杆菌SRA10与未接种对照相比，显著增加了芥菜根和地上部组织中镍的积累。这一结果表明，SRA1和SRA10菌株促进了土壤中不溶性相中镍的释放，从而提高了植物对镍的可利用性。当用SRA2菌株处理种子时，少花龙葵受试植物的生长参数也显著增加，且增幅大于对照。这种效应可归因于ACC的利用、磷的溶解和IAA的产生。研究结果表明，接种镍活化菌株嗜冷杆菌属SRA1和蜡样芽孢杆菌SRA10可通过增强植物组织中的金属积累直接提高植物提取效率，而高效PGPB嗜冷杆菌属SRA2则通过促进芥菜和少花龙葵的生长间接提高植物提取效率。
