Electrochemical enrichment of haloalkaliphilic nitrate-reducing microbial biofilm at the cathode of bioelectrochemical systems

Summary: Electrotrophic microorganisms have not been well studied in extreme environments. Here, we report on the nitrate-reducing cathodic microbial biofilm from a haloalkaline environment. The biofilm enriched via electrochemical approach under 9.5 pH and 20 g NaCl/L salinity conditions achieved −...

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Main Authors: Srishti Chaudhary, Ramandeep Singh, Sukrampal Yadav, Sunil A. Patil
Format: Article
Language:English
Published: Elsevier 2021-06-01
Series:iScience
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S2589004221006507
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author Srishti Chaudhary
Ramandeep Singh
Sukrampal Yadav
Sunil A. Patil
author_facet Srishti Chaudhary
Ramandeep Singh
Sukrampal Yadav
Sunil A. Patil
author_sort Srishti Chaudhary
collection DOAJ
description Summary: Electrotrophic microorganisms have not been well studied in extreme environments. Here, we report on the nitrate-reducing cathodic microbial biofilm from a haloalkaline environment. The biofilm enriched via electrochemical approach under 9.5 pH and 20 g NaCl/L salinity conditions achieved −43.5±7.2μA/cm2 current density and 49.5±13.2%nitrate reduction efficiency via partial and complete denitrification. Voltammetric characterization of the biocathodes revealed a redox center with −0.294±0.003V (vs. Ag/AgCl) formal potential putatively involved in the electron uptake process. The lack of soluble redox mediators and hydrogen-driven nitrate reduction suggests direct-contact cathodic electron uptake by the nitrate-reducing microorganisms in the enriched biofilm. 16S-rRNA amplicon sequencing of the cathodic biofilm revealed the presence of unreported Pseudomonas, Natronococcus, and Pseudoalteromonas spp. at 31.45%,11.82%, and 9.69% relative sequence abundances, respectively. The enriched nitrate-reducing microorganisms also reduced nitrate efficiently using soluble electron donors found in the lake sediments, thereby suggesting their role in N-cycling in such environments.
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spelling doaj.art-3b93d352743e4a4da98a775daa6b642b2022-12-21T19:55:04ZengElsevieriScience2589-00422021-06-01246102682Electrochemical enrichment of haloalkaliphilic nitrate-reducing microbial biofilm at the cathode of bioelectrochemical systemsSrishti Chaudhary0Ramandeep Singh1Sukrampal Yadav2Sunil A. Patil3Department of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), Sector 81, SAS Nagar, Knowledge City, Punjab 140306, IndiaDepartment of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), Sector 81, SAS Nagar, Knowledge City, Punjab 140306, IndiaDepartment of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), Sector 81, SAS Nagar, Knowledge City, Punjab 140306, IndiaDepartment of Earth and Environmental Sciences, Indian Institute of Science Education and Research Mohali (IISER Mohali), Sector 81, SAS Nagar, Knowledge City, Punjab 140306, India; Corresponding authorSummary: Electrotrophic microorganisms have not been well studied in extreme environments. Here, we report on the nitrate-reducing cathodic microbial biofilm from a haloalkaline environment. The biofilm enriched via electrochemical approach under 9.5 pH and 20 g NaCl/L salinity conditions achieved −43.5±7.2μA/cm2 current density and 49.5±13.2%nitrate reduction efficiency via partial and complete denitrification. Voltammetric characterization of the biocathodes revealed a redox center with −0.294±0.003V (vs. Ag/AgCl) formal potential putatively involved in the electron uptake process. The lack of soluble redox mediators and hydrogen-driven nitrate reduction suggests direct-contact cathodic electron uptake by the nitrate-reducing microorganisms in the enriched biofilm. 16S-rRNA amplicon sequencing of the cathodic biofilm revealed the presence of unreported Pseudomonas, Natronococcus, and Pseudoalteromonas spp. at 31.45%,11.82%, and 9.69% relative sequence abundances, respectively. The enriched nitrate-reducing microorganisms also reduced nitrate efficiently using soluble electron donors found in the lake sediments, thereby suggesting their role in N-cycling in such environments.http://www.sciencedirect.com/science/article/pii/S2589004221006507BioelectrochemistryMicrobiofilms
spellingShingle Srishti Chaudhary
Ramandeep Singh
Sukrampal Yadav
Sunil A. Patil
Electrochemical enrichment of haloalkaliphilic nitrate-reducing microbial biofilm at the cathode of bioelectrochemical systems
iScience
Bioelectrochemistry
Microbiofilms
title Electrochemical enrichment of haloalkaliphilic nitrate-reducing microbial biofilm at the cathode of bioelectrochemical systems
title_full Electrochemical enrichment of haloalkaliphilic nitrate-reducing microbial biofilm at the cathode of bioelectrochemical systems
title_fullStr Electrochemical enrichment of haloalkaliphilic nitrate-reducing microbial biofilm at the cathode of bioelectrochemical systems
title_full_unstemmed Electrochemical enrichment of haloalkaliphilic nitrate-reducing microbial biofilm at the cathode of bioelectrochemical systems
title_short Electrochemical enrichment of haloalkaliphilic nitrate-reducing microbial biofilm at the cathode of bioelectrochemical systems
title_sort electrochemical enrichment of haloalkaliphilic nitrate reducing microbial biofilm at the cathode of bioelectrochemical systems
topic Bioelectrochemistry
Microbiofilms
url http://www.sciencedirect.com/science/article/pii/S2589004221006507
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AT sukrampalyadav electrochemicalenrichmentofhaloalkaliphilicnitratereducingmicrobialbiofilmatthecathodeofbioelectrochemicalsystems
AT sunilapatil electrochemicalenrichmentofhaloalkaliphilicnitratereducingmicrobialbiofilmatthecathodeofbioelectrochemicalsystems