IAA production characteristics and growth-promoting effects on pepper of potential plant grouth-promoting rhizobacteria（ PGPR） Bacillus tequilensis U36

We systematically analyzed a potential plant growth-promoting rhizobacteria（PGRP）U36，which was separated from soil. This strain was eventually determined to be Bacillus tequilensis through the morphological， physiological and biochemical properties and 16S rRNA assay. Through the pot experiment，we found that U36 promoted pepper growth，which was better in normal soil than in sterilized soil，but the growth promoting efficiency was much higher in sterilized soil than in normal soil after applying U36. In normal soil，the promoting efficiencies of U36 on root length，root weight，stem length，stem weight and leaf area of pepper were 47.7%，37.5%，21.5%， 69.2% and 8.1%，respectively. While in sterile soil，the promoting efficiencies were 49.2%，58.8%，25.7%，58.2% and 24.1%，respectively. Besides，U36 not only had the functions of nitrogen fixation and phosphate-solubilizing， but also could produce the growth promoting substance IAA，and the generation of IAA had tryptophan dependence. With the excellent growth-promoting effect，U36 can be used as a potential PGPR for the development of biological fertilizer，which has a good application value.