Response of particle-associated bacteria to long-term heavy metal contamination in a tropical estuary

• Published in: World journal of microbiology & biotechnology Vol. 36; no. 5; p. 65
• Main Authors: Sheeba, V. A., Anas, Abdulaziz, Jasmin, C., Vincent, Manu, Parameswaran, P. S.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.05.2020; Springer Nature B.V
• Subjects: Acinetobacter - classification; Acinetobacter - drug effects; Acinetobacter - enzymology; Acinetobacter - isolation & purification; Alphaproteobacteria - classification; Alphaproteobacteria - drug effects; Alphaproteobacteria - enzymology; Alphaproteobacteria - isolation & purification; Aminopeptidase; Applied Microbiology; Bacteria; Bacterial Physiological Phenomena - drug effects; Biochemistry; Biomedical and Life Sciences; Biotechnology; Cadmium; Cellobiase; Contamination; Environmental Engineering/Biotechnology; Environmental impact; Environmental Monitoring; Enzymatic activity; Enzyme activity; Enzymes; Estuaries; Firmicutes - classification; Firmicutes - drug effects; Firmicutes - enzymology; Firmicutes - isolation & purification; Gammaproteobacteria - classification; Gammaproteobacteria - drug effects; Gammaproteobacteria - enzymology; Gammaproteobacteria - isolation & purification; Geologic Sediments - chemistry; Glucosidase; Heavy metals; India; Life Sciences; Lipase; Marine environment; Metals, Heavy - analysis; Metals, Heavy - toxicity; Microbiology; Organic matter; Original Paper; Particulate matter; Particulate Matter - chemistry; Particulate organic matter; Phosphatase; Phylogeny; Pollutants; Remineralization; RNA, Ribosomal, 16S - genetics; RNA, Ribosomal, 16S - isolation & purification; Spatial variations; Terrestrial environments; Upstream; Water Microbiology; Water Pollutants, Chemical - analysis; Zinc; β-Glucosidase; India; Cochin estuary; Bacteria; Enzyme activity; Particulate matter; Heavy metal; Metal tolerance
• ISSN: 0959-3993; 1573-0972
• DOI: 10.1007/s11274-020-02842-1

Estuaries being the connecting link between terrestrial and marine environment, experience spatial variations in the hydrographic variables as well as concentrations of pollutants. The present study reports a contrasting difference in the metal tolerance and enzyme activity of particle-associated bacteria (PAB) isolated from the upstream and downstream reaches of a tropical estuary [Cochin Estuary (CE) in the southwest coast of India], exposed to different levels of heavy metal contamination. The upstream of the estuary has been overloaded with heavy metals in the last few decades, while the downstream is less polluted. There were only 25% of culturable PAB phylogenetically common in both upstream and downstream. The PAB isolated from the upstream were dominated by γ-proteobacteria (48.1%) followed by α-proteobacteria (25.0%), while it was in the reverse order of α-proteobacteria (45.9%) and γ-proteobacteria (36.1%) in the downstream. More number of PAB from the upstream showed tolerance to higher concentrations of Zn and Cd. The Acinetobacter sp. MMRF1051 isolated from the upstream showed tolerance up to 250 mM Zn, 100 mM Cd, and 250 mM Ni. The enzyme expression profile of PAB from downstream was in the order of lipase > phosphatase > β-glucosidase > aminopeptidase, while it was in the order of β-glucosidase > lipase > aminopeptidase > phosphatase in the upstream of the estuary. The present study shows the selective pressure exerted by heavy metal pollution on the diversity of culturable bacteria associated with particulate matter in a tropical estuary. Also, the variation in their enzyme activities may impinge the remineralization of particulate organic matter (POM) in the system and may impart adverse impacts on ecosystem functioning.