Deciphering the bacterial and fungal communities in clubroot-affected cabbage rhizosphere treated with Bacillus Subtilis XF-1

Clubroot is an infection of cruciferous crops which results in considerable yield losses, caused by Plasmodiophora brassicae Woron. Bacillus subtilis XF-1 isolated from the rhizosphere of Chinese cabbages with severe clubroot in Guandu District of Kunming, Yunnan Province, China, has strong inhibitory effects on the resting spores of P. brassicae. However, its potential effects on the soil bacterial and fungal communities are still unknown. In this study, B. subtilis XF-1 was inoculated into cabbage rhizosphere and incidence of clubroot disease was surveyed, furthermore, an effect of this strain on soil microbial community in cabbage rhizosphere was investigated using Biolog™ MicroPlates and 454 pyrosequencing. B. subtilis XF-1 reduced the disease index (DI) by 17.14% and the control efficiency was 76.92%. The results of Biolog analysis and high-throughput pyrosequencing demonstrated that Proteobacteria, Bacteroidetes, Acidobacteria, Actinobacteria, Firmicutes, and Gemmatimonadetes were the dominant taxonomic phyla found among bacteria in ten samples and Ascomycota, Basidiomycota and early diverging fungal lineages were reported among fungi. The soil bacterial and fungal communities were reduced greatly at the beginning, but they were recovered gradually with the growth of plant. However, there was little difference between treatment and control at the mature stage. The present study demonstrated that the effect of B. subtilis XF-1 on soil fungal community in cabbages rhizosphere was just transient and that the high-throughput 454 pyrosequencing is a suitable method for the characterization of microbial communities of rhizosphere soil of cabbage.