Inoculations with Pseudomonas fluorescens and Bacillus cereus affect the soil enzyme activity, growth and rhizosphere microbial diversity of Taxus chinensis var. mairei

Abstract

Taxus chinensis var. mairei is a rare tree endemic to China. Pseudomonas fluorescens CLW17 and Bacillus cereus CLY07 were isolated from the T. chinensis var. mairei rhizosphere and the two strains were efficient phosphate-solubilizing bacteria. We investigated the effect of inoculation with P. fluorescens CLW17 and B. cereus CLY07 on soil enzyme activity, growth and the rhizosphere microbial diversity of Taxus chinensis var. mairei over different time periods. The plant biomass, seedling height, stem diameter and root vitality were measured, so that the inoculation effects of the two bacterial strains on T. chinensis var. mairei seedlings could be evaluated. Three types of soil enzymes (alkaline phosphatase, invertase and dehydrogenase) were identified. The soil microbial community composition and diversity were determined by high-throughput pyrosequencing analysis. Inoculation with P. fluorescens CLW17 and B. cereus CLY07 significantly increased plant biomass, seedling height, stem diameter and root vitality, and improved soil enzyme activities (alkaline phosphatase, invertase and dehydrogenase) (P < 0.05) in T. chinensis var. mairei. High-throughput pyrosequencing of 16S and 18S rRNA genes revealed minor changes in the diversity, relative abundance, and composition of the microbial community in the T. chinensis var. mairei rhizosphere after inoculation. Inoculation with P. fluorescens CLW17 and B. cereus CLY07 promoted T. chinensis var. mairei growth and improved the soil enzyme activity with a small change in rhizosphere microbial diversity. This study provides necessary insight for developing effective, cheap and safe inoculants of strains P. fluorescens CLW17 and B. cereus CLY07 for T. chinensis var. mairei.