Bacterial community analysis on Sclerotium-suppressive soil

Difficulties in controlling the soil-borne plant pathogenic fungus Sclerotium rolfsii favoured the analysis of its suppressive soil for better understanding. In the present study, culture-independent molecular technique was used to analyse the bacterial communities of suppressive soil and conducive soil. Hence, metagenomic DNAs from both kinds of soils were directly extracted and their sequence polymorphism was analysed by targeting hypervariable domains, V4 + V5, of the 16S rRNA gene. The results of 16S rRNA gene-driven bacterial community diversity analysis along with soil physicochemical and biological properties clearly discriminated S. rolfsii suppressive soil from conducive soil. The dominant phylogenetic group of suppressive soil is Actinobacteria followed by Proteobacteria. The other groups include Acidobacteria, Firmicutes and Cyanobacteria. In contrast, conducive soil had very few Actinobacterial sequences and was dominated by Gamma- and Betaproteobacteria. Based on the relative proportion of different bacterial communities, their diversity and species richness were observed more in suppressive soil than in conducive soil. The present study identifies the dominant bacterial community which shares S. rolfsii suppressiveness.