Microbial distribution characteristics around the roots of Kalidium foliatum and the effect of salt concentrations on microbial metabolism analysis

Abstract:

[Background] Kalidium foliatum are typical salt-tolerant plants widely distributed in saline-alkali desert areas. Salt accumulation constructed a salt island in the rhizosphere. There was rare investigation about how the microorganism succeed and adapted in the salt accumulation process. However, it was important to reveal the salt tolerance of Kalidium foliatum and formation of the salt island. [Objective] We analyzed the distribution characteristics of microorganism in soils of the rhizosphere, the root zone and the environment, and determined the effect of different salt concentration treatments on metabolic diversity of rhizosphere bacteria using Biolog Eco microplate. [Methods] Soils of the rhizosphere, the root zone and the environmental were sampled from Heshuo County, Xinjiang. The Biolog Eco microplate technique was used to analyze the utilization of microbial carbon sources. The rhizosphere soil samples were diluted by different NaCl concentrations, and then the dilution was taken to add into Biolog Eco microplates. The effect of the salt concentration on rhizosphere microbial activity and diversity was analyzed. [Results] Microbial metabolic activity of the samples showed a trend of the rhizosphere > the root zone > the environment. With the increase of distance from the root, the proportion of microorganisms using amino acids and amines as carbon sources decreased significantly, while the proportion of microorganisms using polymeric compound carbon sources increased significantly such as Tween, Glycogen and so on. Analysis of diversity showed that the Shannon index (H) decreased with significant difference. The significant effect of dilution solutions in different NaCl concentrations was observed on the metabolic activity and distribution of microbial community. And microbial activity of the rhizosphere was the highest at 5% NaCl solution as dilution solution. [Conclusion] The composition and distribution of microorganisms around the roots of Kalidium foliatum showed obvious evolution regularity. And it is necessary to optimize the cultivation condition using Biolog Eco microplate.