Illumina based high throughput analysis of microbial diversity of maize rhizosphere treated with nanocompounds and Bacillus sp.

Abstract

Soil microorganisms play a crucial role in the maintenance of the ecosystem. Their diverse enzymatic machinery facilitates the biogeochemical cycling of essential macro/micronutrients. Over the past two decades, significant amount of research has been carried out on the application of nanocompounds in agricultural practices. Some reports support the role of nanocompounds in enhancing crop productivity by providing essential nutrients to plants or by exhibiting antimicrobial activities against different phytopathogens. Meagre information is available on long term impact of agriusable nanocompounds along with plant growth promoting rhizobacteria on microbial population of an agriculture field. In this study, attempts have been made to analyse the impact of nanozeolite and nanochitosan (50 mg L−1) along with a bioinoculant (Bacillus sp.) on the bacterial community of maize rhizosphere under field condition. Total bacterial counts, activities of soil health indicator enzymes and total microbial diversity of the experimental maize rhizosphere were assessed using Illumina based high throughput sequencing after 60 days of the experiment. Obtained results indicated higher bacterial diversity in the treated soil than the control which corresponded to increased number of Operational Taxanomic Units (OTUs). Combined treatment of bioinoculant and nanocompounds showed two fold increase in FDA (Fluorescein diacetate hydrolysis), dehydrogenase and alkaline phosphatase activity than the control. Presence of dominant bacterial genera viz. Actinobacteria, Bacteroidetes, Acidobacteria and Chloroflexi were observed in treated soil sample. Combined treatment of Bacillus sp. and nanocompounds had a strong influence on the composition of rhizospheric microbiota, diversity and richness. We propose that the application of nanocompounds along with a potential bioinoculant is beneficial for the survival of rhizospheric bacterial population and soil health.