Abstract：The aim of this study was to determine the diversity of the cultivable Bacillus species population in the rhizosphere of maize (Zea mays). Bacillus species were isolated from 10 soil samples by using the dilution method on NA medium and 69 isolates were obtained through morphological difference, and identified by 16S rRNA. Phylogenetic analysis based on 16S rRNA gene sequencing showed that the 69 isolates were grouped into 3 genera (Bacillus, Lysinibacillus and Psychrobacillus) with 23 distinct species. Most of these species were owned to the genus Bacillus. The number of species isolated from every maize variety was different. The most number of Bacillus species (8 species) occurred in the varieties QB662×QB2219 and QB1013×QB446, and the most colonies occurred in the variety J106×QB572. The dominant populations in the maize rhizosphere were B. aerophilus, B. aryabhattai, B. simplex and B. thuringiensis, other species only occurred in one maize variety or few maize rhizosphere. The highest Shannon-Wiener index was QB662×QB2219, the second was QB948×QB48 but owning the highest evenness index. The lowest Shannon-Wiener index and evenness index was J106×QB572. Strains FJAT-17411, FJAT-17472, FJAT-17430 and FJAT-17442 may be the new species, which had lower similarities with the known Bacillus spcies in GenBank database. In conclusion, the result of this study showed that the population diversity of the cultivable bacteria was abundant and there were some potential novel species in the rhizosphere of maize. The findings provide an important scientific base for the development and utilization of Bacillus resources.
