Tolerance of Microorganisms to Heavy Metals

Heavy metal pollution is a growing environmental concern due to the increase in anthropogenic-based sources. Microorganisms have high adsorptive capacities and surface-area-to-volume ratio that enable the uptake of these contaminants and their conversion to innocuous complexes in the process of bioremediation. This chapter explores the mechanisms and specific microorganisms that are resistant to metal toxicity. A wide range of bacterial, algae, and fungal species used as biosorbents are highlighted. Mechanisms such as reduction of metal cations, their sequestration, and binding on cell barriers are discussed. To optimise the efficacy of microorganisms in bioremediation processes, adoption of genetic and nano-technologies is recommended.

Bacterial Remediation of Chromium From Industrial Sludge

Chromium-like heavy toxic metals seriously influence the metabolism of living organisms and cause permanent threatening of health. Microorganisms can help to detoxify those hazardous heavy metals in the environment by the process of bioremediation. Two bacterial genera were isolated from industrial sludge designated P1 and P2. From the 16srRNA study, it is revealed that P1 is Bacillus cereus and P2 is Enterobacter sp. They are deposited in NCMR and NCBI and received the accession no. MCC 3868 for P1 and MCC 3788 for P2. P1 is gram positive, motile, and P2 is gram negative, motile. Eighteen antibiotics have been taken for antibiotic assay; P1 is resistant to 12; P2 is resistant to 8 antibiotics. For growth pattern analysis in chromium, three parameters have been selected, and they are temperature, pH, and biomass. In LD50 and above parameters, total chromium uptake by those bacteria in stressed conditions have been recorded. The two bacteria are not antagonistic to each other so they are used to bioremediate chromium from their contaminated sites and also treated as consortium.

The Use of Microorganism-Derived Enzymes for Bioremediation of Soil Pollutants

Contamination of soils by xenobiotic compounds is a growing concern for environmentalists amidst the rise of anthropogenic activities that encourage such contamination practices. The use of microbial enzymes is a viable alternative to degrade and mineralize these contaminants, which is a growing research interest owing to its eco-friendly nature. This chapter explores the categories of enzymes used in soil bioremediation such as oxidoreductases and hydrolases, their mechanism of action, and their merits and demerits. Furthermore, molecular biology techniques useful in enhancing the production capacity, stability, activity, and shelf life of bioremediation enzymes is discussed. Ultimately, the need to develop bioremediation enzymes in bulk, using cheap technologies while optimising their activity, stability, and shelf life for effective soil decontamination is emphasized.

Different Bioremediation Techniques for Management of Waste Water

Water contamination remains an issue. A combination of biodegradation and nanotechnology is proposed as a potential proficient, minimal effort, and naturally amiable system to deal with it. Among different mediations, bioremediation procedures can conceivably be utilized to decrease the versatility of materials in the subsurface, reducing the potential for human and ecological exposure. The metabolic diversity of microorganisms ensures an assortment of substrates to be expended. Photosynthetic microorganisms have been found as a compelling and eco-friendly species that can remove carbon, nitrogen, and phosphorous in the manufactured sewage and wastewater. This chapter particularly emphasizes environmentally friendly NMs that give information for removing contaminants from wastewater and effluents. Additionally, various nanocomposites and different natural methods utilized in the wastewater treatment process are also briefly discussed.

An Eco-Friendly Approach for the Eradication of Heavy Metal Contaminants by Nano-Bioremediation

Nanomaterials manifest distinct physical and chemical properties and have received much attention from researchers in different areas of environmental sciences, specifically in bioremediation. However, bioremediation may not always impart contrivable approaches when subjected to high concentrations of contaminants that are harmful to most microorganisms, which include heavy metals and salts. Nanotechnology on the other hand exhibits a number of potential environmental benefits such as treatment and remediation, pollution prevention, and sensing and detection of pollutants. Nanomaterials used towards bioremediation provide less-toxic effects on indigenous microorganisms and improve microbial biodegradation activity. Credibility of nanotechnology to cut down pollution is in its developing stage and could potentially revolutionize the field of environmental sustainability. Nano-bioremediation is a new emerging technique for remediation of pollutants using biosynthetic nanoparticles.

Fungi-Mediated Detoxification of Heavy Metals

Heavy metal pollution is one of the major environmental problems today. Therefore, the elimination of heavy metal ions from wastewater is important to protect public health. The use of biological material in the removal and recovery of toxic metals from industrial wastes has gained important credibility during recent years. Several microorganisms including bacteria, algae, yeast, and fungi have been reported to effectively accumulate or adsorb heavy metals through biosorption. Fungal biomaterial has been proved to be efficient as a biosorbent. High percentage of the cell wall material and availability of fungal biomass as a by-product of various antibiotic and food industries makes it an obvious choice. Thus, the chapter deals with detoxification of heavy metals from contaminated sources using biomaterials with special reference to fungi.

Safety and Efficacy of Pseudomonas Exopolymer in Sequestration of Iron From Aqueous Environments

The present study reports the iron binding characteristics and safety of an exopolymer (EBP) of an environmental isolate of Pseudomonas sp. The EBP was predominantly polysaccharide in composition with pyruvic and uronic acid residues. A prevalence of carboxyl and hydroxyl groups was observed in the Fourier-transform infrared spectroscopy (FTIR) results, while scanning electron microscopy (SEM) revealed a porous structure in a linear fashion with large number of grooves. The purified EBP was stable for over two months and exhibited rapid binding of iron (25mg/L) within 10 minutes at ambient temperature. X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDAX) analysis of iron challenged EBP suggested the involvement of carboxyl groups in potentiating iron removal. Both Langmuir and Freundlich adsorption isotherms depicted high iron removal capacity in comparison to reported biomasses or biopolymers. Cytotoxic effects were not observed upon challenging various doses of EBP in RAW 264.7 cell lines implying a strong possibility of application of the EBP.

Sustainable Treatment of Landfill Leachate Using Constructed Wetlands

Sanitary landfilling is the major method of disposal of municipal solid waste (MSW) in developing countries. The disposal of MSW in landfills generates a large amount of highly toxic leachate, which has high potential hazards for the public, flora, fauna health and ecosystems. Advanced leachate treatment systems using biological and chemical treatment methods are recently implemented in developed countries, but high investment and operating costs restricted their application in most of the developing countries. To overcome this problem, an alternative sustainable treatment technology such as phytoremediation could be beneficial. The constructed wetland treatment system is an economical alternative for leachate treatment using local resources and is an energy-efficient technology. These green systems utilize anaerobic and aerobic reactions to break down, immobilize, or incorporate organic substances and other contaminants from polluted effluent. This chapter highlights the recent advances in the treatment of landfill leachates using constructed wetlands.

Environmental Fluoride

Noteworthy multi-disciplinary undertakings have been taken to investigate the effects of natural fluoride ion (F) contamination since the preceding century. Fluoride is a hazard to the earth and human prosperity. Developed and developing countries are standing up to such enormous extents of issues in light of fluoride in the drinking water. Human use to fluoride has bourgeoned since World War II, on account of fluoridated water and toothpaste just as to the normal defilement by huge ventures, from aluminium to pesticides, where fluoride is an essential mechanical concoction similarly as a waste product. The chapter deals with the proportion of fluoride in nature and its impact on human prosperity, generally on the brain, endocrine system, thyroid, pineal gland, immune system, reproductive system, and organ systems. High assemblies of F in soil may really bargain the life of plants, obliterate soil microbial development, upset the soil environment, and cause soil and water defilement. This chapter further emphasizes various biological approaches for the remediation.

Phytoremediation

This chapter includes the sources of cadmium and chromium contamination of soil and various detrimental effects on plants and animals. Ecofriendly approach of soil clean up by phytoremediation is the main focus of the author. Heavy metal-induced oxidative stress of plants and their detoxification potentiality has been discussed here to create a wholesome idea about the basic and acute need of phytoremediation. Both enzymatic and non-enzymatic antioxidative defense mechanisms and various other biochemical parameters of metal hyperaccumulator plants are mentioned.