Exemplifying an archetypal thorium-EPS complexation by novel thoriotolerant Providencia thoriotolerans AM3

Arpit Shukla,Meenu Saraf,Paritosh Parmar,Baldev Patel,Dweipayan Goswami

doi:10.1038/s41598-021-82863-4

Arpit Shukla, Meenu Saraf + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-82863-4

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Abstract

It is the acquisition of unique traits that adds to the enigma of microbial capabilities to carry out extraordinary processes. One such ecosystem is the soil exposed to radionuclides, in the vicinity of atomic power stations. With the aim to study thorium (Th) tolerance in the indigenous bacteria of such soil, the bacteria were isolated and screened for maximum thorium tolerance. Out of all, only one strain AM3, found to tolerate extraordinary levels of Th (1500 mg L−1), was identified to be belonging to genus Providencia and showed maximum genetic similarity with the type strain P. vermicola OP1T. This is the first report suggesting any bacteria to tolerate such high Th and we propose to term such microbes as ‘thoriotolerant’. The medium composition for cultivating AM3 was optimized using response surface methodology (RSM) which also led to an improvement in its Th-tolerance capabilities by 23%. AM3 was found to be a good producer of EPS and hence one component study was also employed for its optimization. Moreover, the EPS produced by the strain showed interaction with Th, which was deduced by Fourier Transform Infrared (FTIR) spectroscopy.

Highlights

It is the acquisition of unique traits that adds to the enigma of microbial capabilities to carry out extraordinary processes
The aftermaths of atomic bombings of Hiroshima and Nagasaki (1945), more than 2000 nuclear tests (1945–2017), the Chernobyl nuclear power plant disaster (1986) and more recently, the Fukushima Daiichi nuclear disaster (2011), highlight the release of considerable radioactive waste to the environment use of various radionuclides has led to the creation of considerable radioactive waste
The cultivated bacteria were subjected to high concentrations of Th (1000–1500 mg L−1) and the bacterium exhibiting the most thorium resistance, strain AM3 was selected for further studies

Summary

Introduction

It is the acquisition of unique traits that adds to the enigma of microbial capabilities to carry out extraordinary processes One such ecosystem is the soil exposed to radionuclides, in the vicinity of atomic power stations. Only one strain AM3, found to tolerate extraordinary levels of Th (1500 mg L−1), was identified to be belonging to genus Providencia and showed maximum genetic similarity with the type strain P. vermicola OP1T This is the first report suggesting any bacteria to tolerate such high Th and we propose to term such microbes as ‘thoriotolerant’. The rationale of the present study is to cultivate the indigenous bacterial flora of the soil sample collected from the vicinity of an atomic power station. The outcomes of this study have significant repercussions for developing efficient and eco-friendly strategies for microbial remediation of radionuclides

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