Responses of the rhizosphere bacterial community in acidic crop soil to pH: Changes in diversity, composition, interaction, and function.

Soil pH is an important predictor of bacterial community composition and diversity. Examining the effects of pH on diversity, structure, interaction, and function of rhizosphere bacterial communities in acidic crop soils provide valuable information for knowing potential role of rhizosphere bacteria in crop yield. Here, we collected soils from artificial greenhouses and applied Illumina Miseq sequencing, quantitative PCR techniques, multiple ecological analysis methods, including topological analysis and functional profiling to analyze our data and validate our hypotheses. We found that the soil physicochemical properties, species diversity, and rhizosphere bacterial community composition were significantly affected by the degree of soil acidification (pH < 5.5 and pH > 5.5) but not vegetation type. Additionally, bacterial absolute abundance increased with higher pH. The 18 soil samples were clustered into two distinct groups of pH < 5.5 and pH > 5.5 at the OTU level, and soil pH had more of an effect on bacterial community composition compared to the other physicochemical variables. In addition, rhizosphere bacteria might presented relatively less competition for survival in pH < 5.5 soils, and bacterial community functions, including nutrient (i.e., carbon, nitrogen, phosphorus, and sulphur) cycling-related enzymes and proteins, were downregulated in more acidic soils (pH < 5.5) based on sequence analysis. To our knowledge, this report is the first to show that pH is a key factor affecting the diversity, structure, interaction, and function of rhizosphere bacterial communities in acidic crop soil in artificial greenhouses. Our findings emphasize that community function and structure of rhizosphere bacteria are closely correlated in more acidic soils, and the decreased crop yield may be correlated with attenuation of the function of the rhizosphere bacterial community.