Department of Botany and Microbiology, Faculty of Science, Alexandria University, Moharam Bek, Alexandria, 21511, Egypt.
National Institute of Oceanography and Fisheries, NIOF, Cairo, Egypt.
BMC Microbiol. 2022 Jul 7;22(1):174. doi: 10.1186/s12866-022-02587-x.
Phytoremediation is a green technology that removes heavy metal (HM) contamination from the environment by using HM plant accumulators. Among soil microbiota, plant growth promoting bacteria (PGPR) have a role influencing the metal availability and uptake.
This current study evaluates the plant growth promoting qualities of microbial flora isolated from rhizosphere, plant roots, and marine aquatic HMs polluted environments in Alexandria through several biochemical and molecular traits. Metal contents in both collected soils and plant tissues were measured. Transcript levels of marker genes (HMA3 and HMA4) were analyzed.
Three terrestrial and one aquatic site were included in this study based on the ICP-MS identification of four HMs (Zn, Cd, Cu, and Ni) or earlier reports of HMs contamination. Using the VITEK2 bacterial identification system, twenty-two bacteria isolated from these loci were biochemically described. Pseudomonas and Bacillus were the most dominant species. Furthermore, the soil microbiota collected from the most contaminated HMs site with these two were able to enhance the Helianthus annuus L. hyper-accumulation capacity significantly. Specifically, sunflower plants cultivated in soils with HMs adapted bacteria were able to accumulate about 1.7-2.5-folds more Zn and Cd in their shoots, respectively.
The influence of PGPR to stimulate crop growth under stress is considered an effective strategy. Overall, our findings showed that plants cultivated in HMs contaminated sites in the presence of PGPR were able to accumulate significant amounts of HMs in several plant parts than those cultivated in soils lacking microbiota.
植物修复是一种绿色技术，通过使用重金属（HM）植物积累器从环境中去除重金属污染。在土壤微生物群中，植物促生细菌（PGPR）在影响金属可用性和吸收方面发挥作用。
本研究通过几种生化和分子特征评估了从根际、植物根系和受海洋 HM 污染的水生环境中分离的微生物菌群的促生长特性。测量了采集土壤和植物组织中的金属含量。分析了标记基因（HMA3 和 HMA4）的转录水平。
根据 ICP-MS 对四种 HM（Zn、Cd、Cu 和 Ni）的鉴定或先前对 HM 污染的报道，本研究包括三个陆地和一个水生地点。使用 VITEK2 细菌鉴定系统，对从这些部位分离出的 22 种细菌进行了生化描述。假单胞菌和芽孢杆菌是最主要的物种。此外，从受这两种细菌污染最严重的 HM 位点采集的土壤微生物群能够显著提高向日葵的超积累能力。具体来说，在含有 HM 适应细菌的土壤中种植的向日葵植物能够在其茎中分别积累约 1.7-2.5 倍的 Zn 和 Cd。
PGPR 刺激作物在胁迫下生长的影响被认为是一种有效的策略。总的来说，我们的研究结果表明，与在缺乏微生物群的土壤中种植的植物相比，在含有 PGPR 的 HM 污染地点种植的植物能够在多个植物部位积累大量的 HM。
