Effects of Nanoparticles on Plant Growth-Promoting Bacteria in Indian Agricultural Soil

Sangeeta Chavan,Vigneshwaran Nadanathangam

doi:10.3390/agronomy9030140

Abstract

Soil bacteria are some of the key players affecting plant productivity. Soil today is exposed to emerging contaminants like metal engineered nanoparticles. The objective of this study was to evaluate the toxicological effects of silver and zinc oxide nanoparticles on bacteria classified as plant growth-promoting bacteria. Three types of bacteria—nitrogen fixers, phosphate solubilizers, and biofilm formers—were exposed to engineered nanoparticles. Initially, the effect of silver and zinc oxide nanoparticles was determined on pure cultures of the bacteria. These nanoparticles were then applied to soil to assess changes in composition of bacterial communities. Impacts of the nanoparticles were analyzed using Illumina MiSeq sequencing of 16S rRNA genes. In the soil used, relative abundances of the dominant and agriculturally significant phyla, namely, Proteobacteria, Actinobacteria, and Firmicutes, were altered in the presence of silver nanoparticles. Silver nanoparticles changed the abundance of the three phyla by 25 to 45%. Zinc oxide nanoparticles showed negligible effects at the phylum level. Thus, silver nanoparticles may impact bacterial communities in soil, and this in turn may influence processes carried out by soil bacteria.

Highlights

The use of engineered nanoparticles in a wide range of consumer and industrial products is increasing globally
The present study showed negligible effect of zinc oxide nanoparticles on soil bacteria, other studies have shown that they affect soil bacteria as well as soil enzymes at concentrations ranging from 0.1 to 2000 μg/g of soil [34,36,91,92]
The study evaluated the effects of silver and zinc oxide nanoparticles on representatives of three groups of bacteria known to be agriculturally relevant—nitrogen fixers, phosphate solubilizers, and biofilm formers

Summary

Introduction

The use of engineered nanoparticles in a wide range of consumer and industrial products is increasing globally. Silver nanoparticles are being utilized for their antimicrobial properties in textiles, food packaging, wound dressings, medical devices like catheters, paints, water treatment processes, etc. They find a use in optoelectronics, catalysis, surface-enhanced Raman scattering (SERS), and nanoparticle inks for printed electronics [1,2]. Zinc oxide nanoparticles have antimicrobial and UV protective properties and find a use in sunscreens, paints, cosmetics, food packaging, personal care products, etc. In Singapore, the estimated range of release to the aquatic environment of zinc oxide and silver nanoparticles is 1.2–272 t/year and

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