Unraveling the potential of bacteria isolated from the equatorial region of Indian Ocean in mercury detoxification

• Published in: Frontiers in Marine Science Vol. 9
• Main Authors: Joshi, Gajendra, Verma, Pankaj, Meena, Balakrishnan, Goswami, Prasun, Peter, D Magesh, Jha, Dilip Kumar, Vinithkumar, Nambali Valsalan, Dharani, Gopal
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 26.10.2022
• Subjects: FT-IR; GST enzyme; merA gene; Mercury resistant bacteria; Metabolic pathway; Molecular docking
• ISSN: 2296-7745; 2296-7745
• DOI: 10.3389/fmars.2022.986493

The marine environment is most vital and flexible with continual variations in salinity, temperature, and pressure. As a result, bacteria living in such an environment maintain the adaption mechanisms that are inherent in unstable environmental conditions. The harboring of metal-resistant genes in marine bacteria contributes to their effectiveness in metal remediation relative to their terrestrial counterparts. A total of four mercury-resistant bacteria (MRB) i.e. NIOT-EQR_J7 ( Alcanivorax xenomutans ); NIOT-EQR_J248 and NIOT-EQR_J251 ( Halomonas sp.); and NIOT-EQR_J258 ( Marinobacter hydrocarbonoclasticus ) were isolated from the equatorial region of the Indian Ocean (ERIO) and identified by analyzing the 16S rDNA sequence. The MRBs can reduce up to 70% of Hg(II). The mercuric reductase (merA) gene was amplified and the mercury (Hg) volatilization was confirmed by the X-ray film method. The outcomes obtained from ICP-MS validated that the Halomonas sp. NIOT-EQR_J251 was more proficient in removing the Hg from culture media than other isolates. Fourier transform infrared (FT-IR) spectroscopy results revealed alteration in several functional groups attributing to the Hg tolerance and reduction. The Gas Chromatography-Mass Spectrometry (GC-MS) analysis confirmed that strain Halomonas sp. (NIOT-EQR_J248 and NIOT-EQR_J251) released Isooctyl thioglycolate (IOTG) compound under mercury stress. The molecular docking results suggested that IOTG can efficiently bind with the glutathione S-transferase (GST) enzyme. A pathway has been hypothesized based on the GC-MS metabolic profile and molecular docking results, suggesting that the compound IOTG may mediate mercuric reduction via merA-GST related detoxification pathway.