"Gheorghe Asachi" Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Department of Environmental Engineering and Management, 73 Prof. Dr. Docent D. Mangeron Street, 700050 Iasi, Romania.
"Gheorghe Asachi" Technical University of Iasi, Faculty of Chemical Engineering and Environmental Protection, Department of Environmental Engineering and Management, 73 Prof. Dr. Docent D. Mangeron Street, 700050 Iasi, Romania; "Gheorghe Asachi" Technical University of Iasi, Faculty of Hydrotechnical Engineering, Geodesy and Environmental Engineering, Department of Hydrology and Environmental Protection, 65 Prof. Dr. Docent D. Mangeron Street, 700050 Iasi, Romania.
N Biotechnol. 2017 Oct 25;39(Pt A):125-134. doi: 10.1016/j.nbt.2016.09.002. Epub 2016 Sep 9.
Certain species of plants can benefit from synergistic effects with plant growth-promoting rhizobacteria (PGPR) that improve plant growth and metal accumulation, mitigating toxic effects on plants and increasing their tolerance to heavy metals. The application of PGPR as biofertilizers and atmospheric nitrogen fixators contributes considerably to the intensification of the phytoremediation process. In this paper, we have built a system consisting of rhizospheric Azotobacter microbial populations and Lepidium sativum plants, growing in solutions containing heavy metals in various concentrations. We examined the ability of the organisms to grow in symbiosis so as to stimulate the plant growth and enhance its tolerance to Cr(VI) and Cd(II), to ultimately provide a reliable phytoremediation system. The study was developed at the laboratory level and, at this stage, does not assess the inherent interactions under real conditions occurring in contaminated fields with autochthonous microflora and under different pedoclimatic conditions and environmental stresses. Azotobacter sp. bacteria could indeed stimulate the average germination efficiency of Lepidium sativum by almost 7%, average root length by 22%, average stem length by 34% and dry biomass by 53%. The growth of L. sativum has been affected to a greater extent in Cd(II) solutions due its higher toxicity compared to that of Cr(VI). The reduced tolerance index (TI, %) indicated that plant growth in symbiosis with PGPR was however affected by heavy metal toxicity, while the tolerance of the plant to heavy metals was enhanced in the bacteria-plant system. A methodology based on artificial neural networks (ANNs) and differential evolution (DE), specifically a neuro-evolutionary approach, was applied to model germination rates, dry biomass and root/stem length and proving the robustness of the experimental data. The errors associated with all four variables are small and the correlation coefficients higher than 0.98, which indicate that the selected models can efficiently predict the experimental data.
某些植物物种可以受益于与植物促生根际细菌（PGPR）的协同作用，这些细菌可以促进植物生长和金属积累，减轻对植物的毒性影响，提高其对重金属的耐受性。PGPR 作为生物肥料和大气氮固定剂的应用对强化植物修复过程有很大的贡献。在本文中，我们构建了一个由根际固氮菌微生物种群和蕹菜组成的系统，在含有不同浓度重金属的溶液中生长。我们研究了这些生物共生生长的能力，以刺激植物生长，增强其对 Cr(VI) 和 Cd(II)的耐受性，最终提供一个可靠的植物修复系统。该研究是在实验室层面进行的，在现阶段，并不评估在受污染的田地中与土著微生物群落以及在不同的土壤气候条件和环境压力下，实际条件下固有的相互作用。固氮菌可以刺激蕹菜的平均发芽效率提高近 7%，平均根长提高 22%，平均茎长提高 34%，干生物量提高 53%。由于 Cd(II)的毒性比 Cr(VI)更高，因此蕹菜在 Cd(II)溶液中的生长受到了更大的影响。降低的耐受指数（TI，%）表明，与 PGPR 共生的植物生长受到重金属毒性的影响，而植物对重金属的耐受性在细菌-植物系统中得到了增强。基于人工神经网络（ANNs）和差分进化（DE）的方法，特别是神经进化方法，被应用于模型的发芽率、干生物量和根/茎长的建模，证明了实验数据的稳健性。所有四个变量的误差都很小，相关系数都高于 0.98，这表明所选模型可以有效地预测实验数据。
