Bioaccumulation and detoxification of trivalent arsenic by Achromobacter xylosoxidans BHW-15 and electrochemical detection of its transformation efficiency

Farzana Diba,Md Zaved Hossain Khan,Md Sadikur Rahman Shuvo,Arif Istiaq,A S M Rubayet Ul Alam,Salman Zahir Uddin,M Anwar Hossain,Munawar Sultana

doi:10.1038/s41598-021-00745-1

Abstract

Arsenotrophic bacteria play an essential role in lowering arsenic contamination by converting toxic arsenite [As (III)] to less toxic and less bio-accumulative arsenate [As (V)]. The current study focused on the qualitative and electrocatalytic detection of the arsenite oxidation potential of an arsenite-oxidizing bacteria A. xylosoxidans BHW-15 (retrieved from As-contaminated tube well water), which could significantly contribute to arsenic detoxification, accumulation, and immobilization while also providing a scientific foundation for future electrochemical sensor development. The minimum inhibitory concentration (MIC) value for the bacteria was 15 mM As (III). Scanning Electron Microscopy (SEM) investigation validated its intracellular As uptake capacity and demonstrated a substantial association with the MIC value. During the stationary phase, the strain’s As (III) transformation efficiency was 0.0224 mM/h. Molecular analysis by real-time qPCR showed arsenite oxidase (aioA) gene expression increased 1.6-fold in the presence of As (III) compared to the untreated cells. The immobilized whole-cell also showed As (III) conversion up to 18 days. To analyze the electrochemical oxidation in water, we developed a modified GCE/P-Arg/ErGO-AuNPs electrode, which successfully sensed and quantified conversion of As (III) into As (V) by accepting electrons; implying a functional As oxidase enzyme activity in the cells. To the best of our knowledge, this is the first report on the electrochemical observation of the As-transformation mechanism with Achromobactersp. Furthermore, the current work highlighted that our isolate might be employed as a promising candidate for arsenic bioremediation, and information acquired from this study may be helpful to open a new window for the development of a cost-effective, eco-friendly biosensor for arsenic species detection in the future.

Highlights

Arsenic (As) is a hazardous compound that is listed among the World Health Organization’s ten major chemicals of public health concern
We have reported the first electrochemical observation of the As-transformation process by Achromo‐ bacter sp. using a modified GCE/poly L-Arg (P-Arg)/ErGO-AuNPs electrode, which will open the way for future biosensor development research
minimum inhibitory concentration (MIC) at different arsenite concentrations was determined to understand the ability of the strain A. xylosoxidans BHW-15 to withstand a higher concentration of As

Summary

Introduction

Arsenic (As) is a hazardous compound that is listed among the World Health Organization’s ten major chemicals of public health concern It is usually found in the earth’s surface, groundwater, sediment soil, and a ir[1]. Our strain A. xylosoxidans BHW-15 was reported as a novel heterotrophic arsenite oxidizing b acteria[26] with a high MIC value isolated from the tube well water. To date, it showed the highest As transformation and accumulation ability compared to the other reported arsenite oxidizing strains in Bangladesh. Compared to other arsenic metabolizing bacteria, A. xylosoxidans BHW-15 possess a distinctive enrichment of metal resistance genes islands that reflects its high As transformation capacity. Considering its ease of availability, efficiency, and genetic integrity, we chose this strain as a candidate for our bioremediation investigation

Methods

Results

Discussion

Conclusion