دانلود رایگان مقاله غلظت CO2 و تغییر جوامع میکروبی ریزوسفر و توده خاک

Abstract

Using TRFLP and real-time qPCR, this study aimed to investigate the way elevated CO2 (eCO2) affects bacteria, fungi, archaea, and sulfate-reducing bacteria in salt marsh systems containing halophyte Suaeda japonica. Moreover, it also aimed to evaluate the effects of eCO2 in terms of plant interaction by analyzing the rhizosphere and bulk soil separately. We observed that the gene abundance and community structures were affected by eCO2, and the rhizosphere and bulk soil communities showed a different response. The rhizospheric microbes responded to eCO2 more strongly than the bulk soil microbes. The results also showed that the sulfate-reducing bacteria (SRB) community was more sensitive to eCO2 than the general bacterial community. In addition, the findings suggested that bacteria and archaea competed severely when exposed to eCO2, which caused a dominance of bacteria over archaea or the co-presence of bacteria and archaea with a different micro-niche. Overall, eCO2 caused a strong change in the microbial community in salt marsh with halophytes, but the overall functional activity of the microbial community was unchanged and balanced by the different response patterns of the bacterial, fungal, and archaeal communities in our system.

3. Results and discussion

Our results showed that eCO2 increased the dissolved organic carbon in both the rhizosphere and bulk soil (Fig.1). This may have originated from the increase in plant exudate. This increase in exudates may cause the increase in bacterial abundance in the rhizosphere. The eCO2 also increased the SRB abundance in the rhizosphere, while it decreased the abundance in the bulk soil. However, the fungal abundance was not affected by the eCO2 and the archaeal abundance was reduced by the eCO2 in both the rhizosphere and bulk soil (Fig. 2). For the diversity, the eCO2 increased bacterial diversity but decreased the fungal and SRB diversity in the rhizosphere (Fig. 3). Although the bacterial abundance was increased by eCO2, the activities of the 3 types of extracellular enzymes were not significantly affected by the eCO2 (Fig. 1). However, the result of correlation analysis showed that bacterial abundance was positively correlated with the DOC, b-glucosidase, aminopeptidase, and SRB, while the archaeal abundance was negatively correlated with the enzyme activity, and the fungal abundance was not correlated with any parameters (Supplementary data Table S1). This suggests that bacterial groups play a key role in the degradation of organic compounds.