Abundance and Activity of 16S rRNA, AmoA and NifH Bacterial Genes During Assisted Phytostabilization of Mine Tailings

Mine tailings in semiarid regions are highly susceptible to erosion and are sources of dust pollution and potential avenues of human exposure to toxic metals. One constraint to revegetation of tailings by phytostabilization is the absence of microbial communities critical for biogeochemical cycling of plant nutrients. The objective of this study was to evaluate specific genes as in situ indicators of biological soil response during phytoremediation. The abundance and activity of 16S rRNA, nifH, and amoA were monitored during a nine month phytostabilization study using buffalo grass and quailbush grown in compost-amended, metalliferous tailings. The compost amendment provided a greater than 5-log increase in bacterial abundance, and survival of this compost-inoculum was more stable in planted treatments. Despite increased abundance, the activity of the introduced community was low, and significant increases were not detected until six and nine months in quailbush, and unplanted compost and buffalo grass treatments, respectively. In addition, increased abundances of nitrogen-fixation (nifH) and ammonia-oxidizing (amoA) genes were observed in rhizospheres of buffalo grass and quailbush, respectively. Thus, plant establishment facilitated the short term stabilization of introduced bacterial biomass and supported the growth of two key nitrogen-cycling populations in compost-amended tailings.

在半干旱地区，矿业尾矿对侵蚀现象极为敏感，同时也是粉尘污染的源头以及人类接触有毒金属的潜在途径。植物稳定化在尾矿再植被过程中的一大限制因素是缺乏对植物营养生物地球化学循环至关重要的微生物群落。本研究旨在评估特定基因作为原位生物土壤响应指示物在植物修复过程中的应用。在为期九个月的植物稳定化研究中，我们利用在堆肥改良的金属尾矿中种植的百慕大草和雀麦草，监测了16S rRNA、nifH和amoA基因的丰度和活性。堆肥改良使得细菌丰度提高了超过5个对数单位，且在种植处理中，这种堆肥接种物的存活率更为稳定。尽管细菌丰度有所增加，但引入的微生物群落活性较低，直到第六个月和第九个月在雀麦草、未种植的堆肥和百慕大草处理中才检测到显著增加。此外，在百慕大草和雀麦草的根际中，分别观察到了固氮（nifH）和氨氧化（amoA）基因丰度的增加。因此，植物的生长促进了引入的细菌生物量在短期内的稳定，并支持了堆肥改良尾矿中两个关键氮循环种群的生长。