Exploring the impacts of heavy metals on spatial variations of sediment-associated bacterial communities

Meora Rajeev; T J Sushmitha; Chairmandurai Aravindraja; Subba Rao Toleti; Shunmugiah Karutha Pandian

doi:10.1016/j.ecoenv.2020.111808

Exploring the impacts of heavy metals on spatial variations of sediment-associated bacterial communities

Ecotoxicol Environ Saf. 2021 Feb:209:111808. doi: 10.1016/j.ecoenv.2020.111808. Epub 2020 Dec 22.

Authors

Meora Rajeev¹, T J Sushmitha¹, Chairmandurai Aravindraja², Subba Rao Toleti³, Shunmugiah Karutha Pandian⁴

Affiliations

¹ Department of Biotechnology, Science Campus, Alagappa University, Karaikudi 630 003, Tamil Nadu, India.
² Department of Periodontology, College of Dentistry, University of Florida, Gainesville, FL, USA.
³ Water and Steam Chemistry Division, Bhabha Atomic Research Centre Facilities, Kalpakkam 603 102, Tamil Nadu, India.
⁴ Department of Biotechnology, Science Campus, Alagappa University, Karaikudi 630 003, Tamil Nadu, India. Electronic address: sk_pandian@alagappauniversity.ac.in.

PMID: 33360289
DOI: 10.1016/j.ecoenv.2020.111808

Abstract

One of the fundamental objectives in modern ecology is to decipher how bacterial communities in natural environment respond to anthropogenic activities. In recent times consequences of marine pollution, especially with heavy metals (HMs) have received increasing attention. However, insights into the response of bacterial communities to HMs in coastal sediments of India remain scarce. Here, we analyzed HMs content in three areas, along the southern coastal region of India. Based on the calculated pollution indices viz., enrichment factor (EF), contamination factor (CF), geo-accumulation index (Igeo) and sediment quality guidelines (SQGs), the studied areas were classified as uncontaminated, moderately contaminated and significantly contaminated. To explore the response of bacterial community to HMs, sediment-associated microbiota was investigated using high-throughput 16S rRNA gene amplicon sequencing. The obtained metataxonomic results revealed that bacterial diversity and community composition varied considerably in significantly contaminated area than moderately contaminated and uncontaminated areas. Proportion of bacterial classes was higher for Gammaproteobacteria, Betaproteobacteria and Actinobacteria, but lower for Alphaproteobacteria and Flavobacteriia in significantly contaminated area. Also, samples of significantly contaminated area were dominated by well-documented metal-resistant bacterial genera such as Ralstonia and Arthrobacter. Canonical correspondence analysis (CCA) showed that spatial variability of bacterial community composition was strongly correlated with HMs content such as Chromium, Cadmium and Nickel. Further analysis using PICRUSt programme indicated that the predictive functional profile also varied considerably in significantly contaminated area. By linking HMs with bacterial compositional variations, the present study highlights the likely influence of HMs in shaping sedimentary microbiota of coastal regions.

Keywords: Anthropogenic activities; Bacterial community; Heavy metals; Marine sediment; Pollution indices; Predicted functions.

MeSH terms

Bacteria
Cadmium / analysis
Chromium / analysis
Ecology
Environmental Monitoring / methods*
Environmental Pollution / analysis
Geologic Sediments / chemistry
Geologic Sediments / microbiology*
India
Metals, Heavy / analysis
Metals, Heavy / toxicity*
Microbiota
Nickel / analysis
RNA, Ribosomal, 16S
Water Pollutants, Chemical / analysis
Water Pollutants, Chemical / toxicity*

Substances

Metals, Heavy
RNA, Ribosomal, 16S
Water Pollutants, Chemical
Cadmium
Chromium
Nickel