Three Plant Growth-Promoting Rhizobacteria Regulate the Soil Microbial Community and Promote the Growth of Maize Seedlings

Plant growth-promoting rhizobacteria (PGPR) plays an important role in promoting plant growth, enhancing plant stress resistance and controlling biological diseases. This study aimed to evaluate the effects of three PGPR strains ( Pseudomonas koreensis A20, Serratia plymuthica A13 and Pseudomonas mandelii A36) on maize plant biomass, root parameters, soil nutrients and enzyme activities, and microbial diversity in rhizosphere soil by pot experiment and high-throughput sequencing technology. The results showed that the three PGPR strains all had growth-promoting properties such as producing indole-3-acetic acid (IAA) and siderophores. After inoculation with the PGPR strain, the maize seedling height increased significantly by 22.04–35.12%, and the root length increased significantly by 203.98–276.53% ( p < 0.05), soil total nitrogen, phosphorus and potassium increased by 82.86–125.71%,17.69–23.13%, 10.64–12.22% ( p < 0.05). High-throughput sequencing results showed that the abundant bacterial phyla in soil include: Acidobacteria, Patescibacteria, Bacteroidetes, Chloroflexi, Gemmatimonadetes, Firmicutes, Actinobacteria, Proteobacteria, Cyanobacteria, Armatimonadetes, and Verrucomicrobia, which contributed almost 99% of the bacterial sequences. The correlation heat map indicated that soil total nitrogen, available nitrogen, organic matter and total potassium were the main environmental parameters influencing the composition of the microbial communities. This study provides basic data references for PGPR strains to improve the soil micro-ecological environment and promote the growth and development of maize seedlings.