Shifts in microbial community composition in tannery-contaminated soil in response to increased gamma radiation

Mohammad A A Al-Najjar,Majed M Albokari

doi:10.1007/s13213-019-01541-z

Abstract

PurposeContaminated sites from man-made activities such as old-fashioned tanneries are inhabited by virulent microorganisms that exhibit more resistance against extreme and toxic environmental conditions. We investigated the effect of different Gamma radiation doses on microbial community composition in the sediment of an old-fashioned tannery.MethodsSeven samples collected from the contaminated sites received different gamma radiation doses (I = 0.0, II = 5, III = 10, VI = 15, V = 20, VI = 25, and VII = 30 kGy) as an acute exposure. The shift in microbial community structure was assessed using the high throughput 454 pyrosequencing. Variations in diversity, richness, and the shift in operational taxonomic units (OTUs) were investigated using statistical analysis.ResultOur results showed that the control sample (I) had the highest diversity, richness, and OTUs when compared with the irradiated samples. Species of Halocella, Parasporobacterium, and Anaerosporobacter had the highest relative abundance at the highest radiation dose of 30 kGy. Members of the Firmicutes also increased by 20% at the highest radiation dose when compared with the control sample (0.0 kGy). Representatives of Synergistetes decreased by 25% while Bacteroidetes retained a steady distribution across the range of gamma radiation intensities.ConclusionThis study provides information about potential “radioresistant” and/or “radiotolerant” microbial species that are adapted to elevated level of chemical toxicity such as Cr and Sr in tannery. These species can be of a high biotechnological and environmental importance.

Highlights

Gamma radiation is widely used in many applied sciences, especially those fields targeting material improvement, soil and food preservation including sterilization and quality assurance for consumables
Gamma radiation causes cytoplasmic water radiolysis resulting in protein oxidation, which leads to the survival of
The bulk was divided into seven subsamples and around 2.0 g of each sample was exposed to different irradiation doses using an inhouse gamma facility (GC-220E, Nordion Inc., Ottawa, ON, Canada) at a dose rate of 4 kGy/h, where 60Co activity was 23,766 Ci, as follows: I = 0.0 kGy, II = 5 kGy, III = 10 kGy, IV = 15 kGy, V = 20 kGy, VI = 25 kGy, and VII = 30 kGy

Summary

Introduction

Gamma radiation is widely used in many applied sciences, especially those fields targeting material improvement, soil and food preservation including sterilization and quality assurance for consumables. Gamma radiation is a favorable tool for studying soil properties and elimination of soil organisms. Selecting the suitable irradiation dose for a soil is affected by factors like moisture content, hydrocarbon content, soil type, and biological diversity (Nunan et al 2017; VanMensel et al 2017). Shifts in the microbial and biological profile of irradiated soil could be dependent on soil physicochemical properties (i.e., moisture, pH) (Gebremikael et al 2015). Variations in microbial community in an irradiated soil sample could be determined by several factors, such as light, exposure time, organic matter, and biological processes, i.e., fermentation and DNA repair (Brown et al 2015; Gebremikael et al 2015; McNamara et al 2003). Gamma radiation causes cytoplasmic water radiolysis resulting in protein oxidation, which leads to the survival of

Objectives

Methods

Results

Discussion

Conclusion