Isolation And Screening Of The Mineral-Weathering Bacteria From A Sandy Red Soil Profile And Study On Their Phylogenetic Relationships

Red soil is a weathering product via exuberant subtropical bioclimatic interaction, such as bioaccumulation, desiliconization, and the enrichment of iron and aluminum element. For lack of alkali metals and alkaline earth metals and rich in iron, aluminum oxide, leaving the soil to acidic and red. Microorganisms are the earlist life on earth, and widely distributed on the near-surface or surface of the earth. As an essential role in the environment, soil microbes contribute to the release of key nutrients from primary minerals that are required not only for their own nutrition but also for plants. In China, red soil is the most widely distributed soil types. The study on the bacterial diversity and its dissolving mechanism of mineral not only reveals the relationship between microbial diversity and soil physical and chemical factors but also provides a theoretical basis for the formation of soil and the role of biogeochemical cycle by soil microorganisms.In this study, the soil samples of the profile (depth ranging from 0 cm to 100 cm) that developed from granite were collected in ying tan, Jiangxi Province. The physical and chemical properties of the soil samples were analyzed by XRD and other conventional methods. The results showed that there was little difference between the weathering degrees of the tested soil samples. But the differences between physical and chemical properties were significant, such as the soil organic matter, activity of urease and invertase, and the major elements.A total of 261 cultured bacteria were isolated from the different soil samples through traditional culture method. The weathering of biotite by the isolates was evaluated. The results showed that all of the cultured bacteria had the ability to weather the mineral. The proportion of the highly effective Fe solubilizers was significantly higher in the deeper horizon, while the proportion of the highly effective Si solubilizers was significantly higher in the upper horizons. Besides, the upper and the deeper horizons also had the highly effective Al and K solubilizers.Two bacterial strains, E2 and F31, were selected as the tested strains for further study. Strain E2 had better adaptability and shorter lag phase than F31. According to the element release, change of pH and organic acids, acids could promote mineral weathering. Oxalic and tartaric acids had better effect on the element release. Meanwhile, there was a positive correlation between Fe and Al release from biotite.Based on the 16S rDNA sequence and phylogenetic analysis, all strains belonged to Burkholderia, Ralstonia, Bacillus, Cupriavidus, Lysinibacillus, Microbacterium,Myroides, Proteus, Paenibacillus, Cellulomomas, Curtobacterium, Leifsonia, Arthrobacter, Kocuria, Ochrobactrum, Enterobactrum, Providrobacter, Enhydrobacter, pseudomonas. The most dominant population of the mineral-weathering bacteria in the samples were Burkholderia and Bacillus, and the second are Ralstonia, Cupriavidus, Curtobacterium and Microbacterium. Canonical Correlation Analysis (CCA) suggested that available element (Fe, Mg, Ca, K and Si) and OM contents, soil moisture, pH, urease activity were related to the population distribution of the bacteria.