CO-OCCURRENCE PATTERNS OF BACTERIAL AND FUNGAL COMMUNITIES ACROSS PH GRADIENT IN SALINE-ALKALINE GRASSLAND SOIL

Soil pH is a critical environmental parameter strongly correlating with microbial communities under various biogeochemical conditions. However, little is known about the co-occurrence pattern of microbial membership in compartments associated with different pH ranges of saline-alkaline grassland soils. To address this gap, we performed a network-based analysis using bacterial and fungal community datasets to characterize co-occurrence patterns and network topological features in four soil pH ranges in a saline-alkaline grassland. Our results indicate that the network topological features of the bacterial and fungal communities differ significantly between different pH ranges in the saline-alkaline grassland. The bacterial co-occurrence pattern in the pH range of 8.0-8.5 was more complex but less stable than that in the other pH ranges, while the fungal co-occurrence pattern had the opposite trend, being less complex but more stable in the pH range of 8.0-8.5. Our co-occurrence analysis identified 14 bacterial species (mainly Proteobacteria and Chloroflexi) and 5 fungal species (mainly in Ascomycota) as key taxa. Overall, our study provides insights into the effects of soil pH on microbial co-occurrence structure and identifies key microbial species in the saline-alkaline grassland of North China. These findings have practical implications for adjusting soil pH and core species to mediate soil microbial co-occurrence structure in saline-alkaline grasslands.