title: Mercury alters the bacterial community structure and diversity in soil even at concentrations lower than the guideline values.
abstract: This study evaluated the effect of inorganic mercury (Hg) on bacterial community and diversity in different soils. Three soils-neutral, alkaline and acidic-were spiked with six different concentrations of Hg ranging from 0 to 200 mg kg-1and aged for 90 days. At the end of the ageing period, 18 samples from three different soils were investigated for bacterial community structure and soil physicochemical properties. Illumina MiSeq-based 16s ribosomal RNA (rRNA) amplicon sequencing revealed the alteration in the bacterial community between un-spiked control soils and Hg-spiked soils. Among the bacterial groups, Actinobacteria (22.65%) were the most abundant phyla in all samples followed by Proteobacteria (21.95%), Bacteroidetes (4.15%), Firmicutes (2.9%) and Acidobacteria (2.04%). However, the largest group showing increased abundance with higher Hg doses was the unclassified group (45.86%), followed by Proteobacteria. Mercury had a considerable negative impact on key soil functional bacteria such as ammonium oxidizers and nitrifiers. Canonical correspondence analysis (CCA) indicated that among the measured soil properties, Hg had a major influence on bacterial community structure. Furthermore, nonlinear regression analysis confirmed that Hg significantly decreased soil bacterial alpha diversity in lower organic carbon containing neutral and alkaline soils, whereas in acidic soil with higher organic carbon there was no significant correlation. EC20values obtained by a nonlinear regression analysis indicated that Hg significantly decreased soil bacterial diversity in concentrations lower than several guideline values.
authors.affiliation: Global Centre for Environmental Remediation (GCER) and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), Faculty of Science and Information Technology, The University of Newcastle, ATC Building, Level 1, University Drive, Callaghan, NSW, 2308, Australia.
authors.forename: Khandaker Rayhan
authors.initials: KR
authors.lastname: Mahbub
authors.affiliation: Global Centre for Environmental Remediation (GCER) and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), Faculty of Science and Information Technology, The University of Newcastle, ATC Building, Level 1, University Drive, Callaghan, NSW, 2308, Australia.
authors.forename: Suresh Ramraj
authors.initials: SR
authors.lastname: Subashchandrabose
authors.affiliation: Global Centre for Environmental Remediation (GCER) and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), Faculty of Science and Information Technology, The University of Newcastle, ATC Building, Level 1, University Drive, Callaghan, NSW, 2308, Australia.
authors.forename: Kannan
authors.initials: K
authors.lastname: Krishnan
authors.affiliation: Global Centre for Environmental Remediation (GCER) and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), Faculty of Science and Information Technology, The University of Newcastle, ATC Building, Level 1, University Drive, Callaghan, NSW, 2308, Australia.
authors.forename: Ravi
authors.initials: R
authors.lastname: Naidu
authors.affiliation: Global Centre for Environmental Remediation (GCER) and Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), Faculty of Science and Information Technology, The University of Newcastle, ATC Building, Level 1, University Drive, Callaghan, NSW, 2308, Australia. megh.mallavarapu@newcastle.edu.au.
authors.forename: Mallavarapu
authors.initials: M
authors.lastname: Megharaj
mesh_terms: D061271:Acidobacteria / Q000187:drug effects / Q000235:genetics; D039903:Actinobacteria / Q000187:drug effects / Q000235:genetics; D041963:Bacteroidetes / Q000187:drug effects / Q000235:genetics; D000068536:Bacillota / Q000187:drug effects / Q000235:genetics; D008628:Mercury / Q000494:pharmacology*; D064307:Microbiota / Q000187:drug effects*; D020560:Proteobacteria / Q000187:drug effects / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D012987:Soil; D008628:Mercury
keywords: 16s rRNA; Bioavailable mercury; Ecological investigation level (EIL); Illumina Miseq; Soil DNA; Toxicity