Marine Pollution and Microbial Remediation

Milind Mohan Naik Santosh Kumar Dubey Editors

Marine Pollution and Microbial Remediation

Springer

E ditors M ilind M ohan N aik D epartm ent o f M icrobiology G oa U niversity Taleigao Plateau, G oa, India

ISB N 978-981-10-1042-2 D O I 10.1007/978-981-10-1044-6

S antosh K u m ar D ubey D epartm ent o f M icrobiology G o a U niversity T aleigao P lateau , G oa , India

ISB N 978-981-10-1044-6

(eB ook)

Library of Congress Control Number: 2016948708 © Springer Science+Business Media Singapore 2017 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. Printed on acid-free paper This Springer imprint is published by Springer Nature The registered company is Springer Science+Business Media Singapore Pte Ltd.

Lead- and Mercury-Resistant Marine Bacteria and Their Application in Lead and Mercury Bioremediation Milind M. Naikand S.K. Dubey

Abstract

With rapid industrialisation, enormous amounts of industrial waste includ­ ing heavy metals have accumulated in marine environments over several decades and require special attention. Untreated wastes from mining, metal refining industries, battery manufacturing industries, sewage sludge, power plants and waste incineration plants often contain substantially high levels of lead (Pb) and mercury (Hg); when dumped into marine and estuarine waters, these pose serious threat to environmental biota and urgently need to be removed from polluted marine/estuarine sites. Lead and mer­ cury are non-bioessential, persistent and hazardous heavy metal pollutants of environmental concern. Bioremediation of heavy metals using Pb- and Hg-resistant bacteria has become a potential alternative to the existing technologies for the removal and/or recovery of toxic Pb and Hg from waste waters before releasing it into marine/estuarine water bodies for environmental safety. Various strategies through which marine/estuarine bacteria resist high concentrations of lead/mercury include efflux mecha­ nisms, extracellular sequestration, biosorption, precipitation, reduction, volatilisation, alteration in cell morphology, enhanced siderophore pro­ duction, altered permeability, demethylation and intracellular bioaccumu­ lation. These unique characteristics of marine/estuarine bacteria proved to be an ideal tool in bioremediation of lead and mercury from contaminated marine and estuarine environmental sites.

3.1

M.M. Naik ( * ) • S.K. Dubey Departm ent of Microbiology, Goa University, Taleigao Plateau, Goa, India e-mail: milindnaik4@ gm ail.com

Introduction

M etals that have a specific gravity greater than 5 or density more than 5 g/cm3 are termed as heavy metals, e.g. mercury, lead, copper and cadmium (Gadd 1992; Dash and Das 2012). The International Union of Pure and Applied

© Springer Science+Business M edia Singapore 2017 M.M. Naik, S.K. Dubey (eds.), M arine Pollution and M icrobial Remediation, DO I 10.1007/978-981-10-1044-6_3

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Chemistry (IUPAC) technical report has elim i­ nated the term “heavy metal” , and the alternative name proposed is “toxic m etal” (Duffus 2002), but still the term “heavy m etal” is used exten­ sively in scientific world. Contamination of marine and freshwater bodies due to release of “toxic metals” lead and mercury poses serious threat to natural biota including humans (Nies 1999; Fernandes and Beiras 2001; Dirilgen 2011; Dash and Das 2012). U ntreated wastes from mining, m etal refining industries, car bat­ tery manufacturing industries, sewage sludge, hydroelectric pow er plants, paper and pulp industries and waste incineration plants often contain substantially high levels of P b and Hg when dumped into marine/estuarine waters, pose serious threat to environmental biota (Naik et al. 2012d, 2013; De et al. 2014). It is interesting to mention that even Antarctic Ocean water, which is considered relatively m ore pristine than any other ocean water, is also contaminated with heavy metals due to anthropogenic activities (Bonner 1984). Lead and mercury do not have any biological function and are toxic to cells in a variety of ways which include DNA damage, oxidative damage to proteins and lipids and binding to essential proteins and enzymes (Nies 1999; Asmub et al. 2000; Hartwig et al. 2002; Naik et al. 2012a, 2013; De et al. 2014). However, the most com ­ mon route of exposure to mercury and lead is by eating marine fish containing methylmercury and lead (Eisler 1988; Nascimento and ChartoneSouza 2003; De et al. 2014). Due to rapid indus­ trialisation, enormous amounts of industrial waste containing heavy metals such as (mercury and lead) have accumulated in marine and terres­ trial environments over several decades and require special attention. Therefore, the US Environmental Protection Agency (EPA) has included lead and mercury in the list of the most hazardous inorganic wastes (Cameron 1992). Lead and mercury are mutagenic and terato­ genic metals causing severe deleterious effects on human beings such as neurodegenerative impairment, renal failure, reproductive damage, neurological diseases and cancer (Kumagai and

M.M. Naik and S.K. Dubey

Nishimura 1978; Lam et al. 2007; Naik et al. 2012b; Naik and Dubey 2013b). Bioavailability of metals is an important factor for metal toxicity since soluble metals can readily penetrate cell membranes (Roane 1999). Therefore, metal immobilisation or detoxification strategies are applied by microbes to counteract toxic effect of heavy metals. Some natural microbial population that possesses a variety of protective mechanisms can survive and colonise at very high concentra­ tions of toxic lead and mercury without any impact on their growth and metabolism. This unique characteristic of heavy metal-resistant microbes including bacteria makes them an ideal tool for bioremediation of metal-contaminated marine and terrestrial sites. Various strategies through which they resist high concentrations of heavy metals include efflux mechanism, altera­ tion in cell morphology, siderophore production, biosorption, precipitation, volatilisation, reduc­ tion, demethylation, oxidation, extracellular sequestration, reduced permeability and intracel­ lular bioaccumulation (Borremans et al. 2001; Barkay et al. 2003; N aik et al. 2012a, 2013; Naik and Dubey 2013b; De et al. 2014). Bioremediation processes are cost effective, highly efficient and environment friendly as compared to physico­ chemical methods for removal of toxic metals; therefore, over the last few decades, attention has been focused towards exploiting marine microbes for heavy metal bioremediation. Understanding the mechanism by which marine and estuarine bacteria sequester/detoxify/biotransform lead and mercury to protect themselves from their toxic effects on physiological processes is crucial to the development of microbial processes for their concentration, removal and recovery from industrial effluents, sewage, marine sediments and marine/estuarine waters. In the present chapter, we are focusing on lead- and mercury-resistant marine and estuarine bacteria and how we can employ them to bioremediate marine and estuarine sites highly con­ taminated with lead and mercury. Here we will stress on various resistant mechanisms employed by marine and estuarine bacteria to resist very high concentrations of lead and mercury and

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Lead- and Mercury-Resistant Marine Bacteria and Their Application in Lead and Mercury.

exploitation of these resistant mechanisms to clean up and biomonitor m arine and estuarine contaminated sites.

3.2

Lead and Mercury Pollution in Marine and Estuarine Environments

3.2.1

Mercury

Mercury is the sixteenth rarest element on earth; however, concentrations of global mercury has increased approximately threefold due to various anthropogenic activities, and the w orld’s oceans are the m ajor reservoirs for its deposition (Mason et al. 2012 ; De et al. 2014). Various anthropo­ genic sources of mercury are burning of coal and petroleum products, dental fillings, use of m ercu­ rial fungicides in agriculture, paper making industry and mercury catalysts in industries. Inorganic and organic mercury compounds such as elemental mercury (Hg0) , mercuric mercury (Hg+2), methylmercuric chloride (MMC) and dimethylmercury are discharged into marine environment through untreated sewage and industrial effluents (Wang et al. 2004; Dash and Das 2012; De et al. 2014). According to some recent models on the flow of mercury through the environment, it is sug­ gested that natural sources account for about 10 % of the estimated 5500-8900 tons of m er­ cury currently being released to the atmosphere from all sources (De et al. 2014). M inamata dis­ ease which causes severe neurological disorder and was discovered in M inamata Bay, Japan, in 1956 is the first record of severe mercury poison­ ing in people who consumed marine fish and shellfish from mercury-contaminated marine waters. Thousands of people where affected and 887 were killed (Nascimento and ChartoneSouza 2003). In M inamata Bay, very high level of mercury was reported which caused a serious neurological disorder in humans referred as “M inamata disease”. The level of total mercury in seawater of M inamata Bay ranged from 56 to 285 ng/L and 2.1-506 ng/L (Kumagai and Nishimura 1978). Interestingly, surface sediment

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sample from semi-enclosed bay, “Gunnekleivfjorden” from Southwest Norway, contained mercury ranging from 90 to 350 ppm (Skei 1978) . The mercury concentrations anal­ ysed along Indian coasts at (i) Mormugao (15°24"35' N, 73°48"2' E; Hg concentration 152-456 ng/l in water and 53-194 ng/g dry sedi­ ment), (ii) Gopalpur (19°18"12' N, 84°57"55' E; Hg concentration 2-117 ng/l in water and 72-128 ng/g dry sediment) and (iii) Chennai (13°6"40' N, 80°18"3' E; Hg concentration 100-2,100 ng/l in water and 237-338 ng/g dry sediment) were found to be very high (De et al. 2007). Methylmercury is the most toxic among all the forms of mercury, affecting the immune system, altering the genetic system and causing damage to the nervous system including coordination and the senses of touch, taste and sight (De et al. 2014). M ercury causes toxicity by binding to the sulfhydryl groups of enzymes and proteins, thereby inactivating crucial cell functions. Generally, mercury accumulates upwards through aquatic food chains, so that organisms at higher trophic levels have higher mercury concentra­ tions (Nascimento and Chartone-Souza 2003). Mercury is of environmental concern because it biomagnifies in the food chain by up to seven orders of magnitude, resulting in high concentra­ tions in top predators such as fish and polar bears (Hintelmann 2010; Sonne 2010). Europe and North America are reducing their contribution towards the global mercury burden, but the emis­ sion rates in Asia are increasing at frightening rates (Dash and Das 2012) and need special attention.

3.2.2

Lead

Lead (Pb), obtained mainly from galena ore (PbS), is known to mankind for last 7,000 years, and its poisoning has been reported for at least 2,500 years (Nriagu 1978; Eisler 1988). Lead is well known to inhibit haem biosynthesis, causes serious neurodegenerative diseases and repro­ ductive impairment, interferes with kidney func­ tion, possesses carcinogenic properties and, when blood level exceeds 70 ^g/dl, results in coma and

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death (Naik et al. 2012b). Lead is known to cause damage to DNA, protein and lipid and to also replace essential metal ions such as Zn, C a and Fe from enzymes (Nies 1999; Asmub et al. 2000; Naik et al. 2013). Lead has broad range of appli­ cations in various industries viz. petroleum, elec­ tronics, battery, paints, ceramics, stained glass, biocide preparation and ammunitions with annual global demand of refined lead exceeding 87 lakh tonnes (Naik et al. 2012c, 2013). Lead is a non­ bioessential persistent environmental pollutant with half-life of approximately 5,000 years and biomagnifies through the trophic levels and accu­ mulates at high concentrations in top predators such as fish and polar bears. Environmental lead has increased more than 1,000-fold over the past three decades as a result of extensive anthropo­ genic activities (Naik et al. 2013). The WHO has recommended