College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, 410128, China.
School of Resources and Environment, Yili Normal University, Yining, 835000, China.
Environ Sci Pollut Res Int. 2024 Apr;31(20):28922-28938. doi: 10.1007/s11356-024-33032-3. Epub 2024 Apr 2.
Miscanthus has good tolerance to multi-metal(loid)s and has received increasing attention in remediated studies of metal(loid)s-contaminated soil. In this study, we conducted phytoextraction techniques to investigate the synergic effects of remediation of multi-metal(loid)s-contaminated soil by Miscanthus floridulus (Lab.) and two plant growth-promoting bacteria (PGPB), TS8 and MR2, affiliated to Enterobacteriaceae. The results exhibited a decrease of arsenic (15.27-21.50%), cadmium (8.64-15.52%), plumbum (5.92-12.76%), and zinc (12.84-24.20%) except for copper contents in the soil in bacterial inoculation groups, indicating that MR2 and TS8 could enhance the remediation of metal(loid)s. Moreover, increased fresh/dry weight and height indicated that inoculated bacteria could promote Miscanthus growth. Although the activities of antioxidant enzymes and the content of chlorophyll in the overground tissues showed no significant increase or even decrease, the activities of antioxidant enzymes in the underground tissues and soil were elevated by 48.95-354.17%, available P by 19.07-23.02%, and available K by 15.34-17.79% (p < 0.05). Bacterial inoculants could also decrease the soil pH. High-throughput sequencing analysis showed that the bacterial inoculant affected the rhizosphere bacterial community and reduced community diversity, but the relative abundance of some PGPB was found to increase. Phylogenetic molecular ecological networks indicated that bacterial inoculants reduced interactions between rhizosphere bacteria and thereby led to a simpler network structure but increased the proportion of positive-correlation links and enhanced the metabiosis and symbiosis of those bacteria. Spearman's test showed that OTUs affiliated with Enterobacteriaceae and soil nutrients were critical for metal(loid) remediation and Miscanthus growth. The results of this study provide a basis for the synergic remediation of multi-metal(loid)s-contaminated soils by Miscanthus and PGPB and provide a reference for the subsequent regulation of Miscanthus remediation efficiency by the other PGPB or critical bacteria.
芒属植物对多种金属（类）具有良好的耐受性，在受金属（类）污染土壤的修复研究中受到越来越多的关注。在这项研究中，我们采用植物提取技术，研究了小花甜茅（Lab.）和两种植物促生菌（PGPB）TS8 和 MR2 对多金属（类）污染土壤的协同修复作用，它们分别属于肠杆菌科。结果表明，接种细菌后，土壤中砷（15.27-21.50%）、镉（8.64-15.52%）、铅（5.92-12.76%）和锌（12.84-24.20%）的含量降低，而铜的含量没有变化，这表明 MR2 和 TS8 可以增强金属（类）的修复效果。此外，接种细菌可以促进芒属植物地上部分鲜重/干重和株高的增加。虽然地上部分抗氧化酶活性和叶绿素含量没有显著增加甚至下降，但地下部分和土壤中的抗氧化酶活性分别提高了 48.95-354.17%、有效磷提高了 19.07-23.02%、有效钾提高了 15.34-17.79%（p<0.05）。细菌接种剂还可以降低土壤 pH 值。高通量测序分析表明，细菌接种剂影响根际细菌群落，降低了群落多样性，但发现一些 PGPB 的相对丰度增加。系统发育分子生态网络分析表明，细菌接种剂减少了根际细菌之间的相互作用，从而导致网络结构变得更简单，但增加了正相关连接的比例，增强了这些细菌的共生关系。Spearman 检验表明，肠杆菌科和土壤养分的 OTUs 对金属（类）修复和芒属植物生长至关重要。本研究结果为芒属植物和 PGPB 协同修复多金属（类）污染土壤提供了依据，为后续通过其他 PGPB 或关键细菌来调节芒属植物修复效率提供了参考。
