Arsenic contamination of groundwater has remained a critical open issue in numerous world areas, especially in Uttar Pradesh in India, in light of its intense and ceaseless harmfulness and cancer-causing properties. In 1993, the World Health Organization set an arsenic permissible level of 10ug/L in its drinking water rules. Practical procedures to expel arsenic from ground water must be produced to make water fit for drinking. Previous studies have shown that this region of India is characterized by extensive As pollution of rivers and ground waters by both geologic and anthropogenic activities. The various other states, including, Jharkhand and Bihar are at biggest risk, because of the flood plain of the Ganga River. In many foods a trace amount of arsenic is essential for good health. However, the excess of this element causes cellular damage in biological system, like gastrointestinal and respiratory disorder. Skin, liver and bladder cancer. Both inorganic arsenate As and arsenite As exist together in natural environment. Arsenite is more toxic than arsenate. As frequently prevails as 74 to 98% of aggregate arsenic. Arsenic is harder to evacuate than As. Utilizing ordinary methods, for example, precipitation, adsorption, particle trade and layer filtration and coagulation were used to remove arsenic from contaminated waters. All these methods are expansive and a source of pollution. Microbial As oxidation has been viewed as an appealing option in light of its particular response for As. The biological mechanism of arsenic removal is possible because of presence of arsenite oxidase and transporter genes studied in various microorganisms like Alkalilimnicola ehrlichii strain MLHE-1. Alcaligenes faecalis. Rhizobium sp. strain NT-26 and Hydrogenophaga sp. strain NT-14. Different heterotrophic and chemolithoautotrophic As oxidizing microscopic organisms have been separated from distinctive situations. Chemolithoautotrophic As oxidizing microorganisms can use As as an electron benefactor and As oxidation can bolster their development, while the oxidation of As by heterotrophic As oxidizing microbes is by and large thought to be a detoxification instrument. Since CAOs by and large demonstrate a higher particular As oxidizing rate than HAOs.
Table of Contents
1. Introduction
1.1 Background of the Research
1.2 Aims and Objectives of the Research
1.3 Research Purpose
2. Literature Review
2.0 Overview of Arsenic
2.1.1 Chemical forms of Arsenic
2.1.2 Arsenic Oxides
2.2.0 Phases of Arsenic
2.2.1 Solution Phase
2.2.2 Precipitation of Arsenic Phases
2.3 Arsenic Toxicity
2.4 Geogenic Arsenic Contamination
2.5 The origin of arsenic in Southeast Asia
2.6 Geochemistry and Mobilization of Arsenic in India
2.6.1 Hydrologic Processes Influencing Groundwater Arsenic Mobilization
2.6.2 Fractionation of Arsenic Implications for Mobility
2.6.3 Organic Matter Associations
2.6.4 Release of Arsenic from Sediments and Soils
2.6.5 Effect of Water Chemistry on As Release from Streambeds
2.6.6 Effect of Ionic Strength on As Release from Sediments
2.6.7 Effect of Redox Conditions on Arsenic Release from Sediments
2.7 Arsenic mobilization
2.8 The Microbial Ecology of High Arsenic Aquifers
2.8.1 Arsenite oxidizing microorganisms
2.8.2 Microbial Intracellular and Extracellular Sequestration
2.8.3 Microbial Arsenic Transformation
2.8.4 Possible biological arsenic removal mechanism and Dimethyl sulfoxide (DMSO) Reductase Family
3. Materials and Methods
3.1 Site description
3.2 Surface and ground water Sampling and Arsenic (As) Concentration Analysis
3.2.1 Sample collection for As Analysis
3.2.2 Microbiological analysis of surface and ground water samples
3.2.3 Analytical Procedure for detection of Arsenic
3.2.4 Determination of surface and ground water pH
3.2.5 Isolation of Arsenite Oxidizing Bacteria
3.3 Phenotypic and Biochemical characterization
3.3.1 Cultural characteristics
3.3.2 Morphological characteristics
3.3.3 Methyl red test
3.3.4 Voges-Proskauer test
3.3.5 Indole formation
3.3.6 Acid from carbohydrate utilization
3.3.7 Starch hydrolysis
3.3.8 Gelatin hydrolysis
3.3.9 Hydrogen sulfide production
3.3.10 Catalase test
3.3.11 Oxidase test
3.4 Physiological characteristics
3.4.1 Determination of optimum pH
3.4.2 Determination of optimum Temperature
3.4.3 Determination of minimum inhibitory concentrations (MIC)
3.4.4 Screening of arsenite oxidizing bacteria
3.5 Genotypic Characterization of the Isolates
3.5.1 Genomic DNA extraction and PCR amplification:
3.5.2 Electrophoresis
3.5.3 Band purification
3.6 DNA sequencing of the samples
3.7 16S rDNA Sequence Analysis
3.8 Amplification of arsenite transporter genes arsB, ACR3 (1) and ACR3 (2)
3.9 Amplification of arsenite oxidase aroA and aroB gene.
Research Goals and Thematic Focus
The primary aim of this research is the isolation and characterization of arsenite-oxidizing bacteria from arsenic-contaminated ground and surface water across five districts in Uttar Pradesh, India, to evaluate their potential for bioremediation.
- Arsenic contamination levels in regional surface and groundwater sources.
- Isolation and culture-based identification of arsenic-resistant bacterial strains.
- Phenotypic and biochemical profiling of identified arsenite-oxidizing microorganisms.
- Genotypic characterization, including 16S rDNA sequencing and analysis of arsenic-resistance genes (arsB, ACR3, aroA, aroB).
Excerpt from the Book
1.1 Background of the Research
Arsenic (As) contamination of groundwater has remained a critical open issue in numerous world areas, especially in Uttar Pradesh in India, in light of its intense and ceaseless harmfulness and cancer-causing properties (Srivastava and Sharma 2013). In 1993, the World Health Organization set an arsenic permissible level of 10µg/L in its drinking water rules (WHO, 2011). Practical procedures to expel arsenic from ground water must be produced to make water fit for drinking (Duan et al., 2013). Previous studies have shown that this region of India is characterized by extensive As pollution of rivers and ground waters by both geologic and anthropogenic activities.
The various other states, including, Jharkhand and Bihar are at biggest risk, because of the flood plain of the Ganga River (Ahamed et al., 2006; Srivastava and Sharma 2013). In many foods a trace amount of arsenic (1µg g-1) is essential for good health. However, the excess of this element (above permissible limit) causes cellular damage in biological system, like gastrointestinal and respiratory disorder. Skin, liver and bladder cancer (Kongkea et al., 2010; Shankar et al., 2014). Both inorganic arsenate As (V) and arsenite As (III) exist together in natural environment. Arsenite is more toxic than arsenate. As (III) frequently prevails as 74 to 98% of aggregate arsenic. Arsenic (III) is harder to evacuate than As (V). Utilizing ordinary methods, for example, precipitation, adsorption, particle trade and layer filtration and coagulation were used to remove arsenic from contaminated waters. Ahmed, 2003; Ghosh et al., 2014). All these methods are expansive and a source of pollution. Microbial As (III) oxidation has
Summary of Chapters
1. Introduction: Discusses the global and regional context of arsenic contamination, specifically focusing on the critical situation in Uttar Pradesh, and defines the research objectives.
2. Literature Review: Provides a comprehensive overview of arsenic chemistry, toxicity, geogenic contamination in Southeast Asia, and the current state of knowledge regarding microbial arsenic mobilization and oxidation.
3. Materials and Methods: Details the site selection process in five districts, water sampling protocols, and the specific microbiological, analytical, and molecular methods used to identify and characterize arsenic-oxidizing bacteria.
Keywords
Arsenic, Arsenite, Bioremediation, Groundwater, Surface Water, Uttar Pradesh, 16S rDNA, Arsenite Oxidase, Bacterial Characterization, arsB, ACR3, aroA, aroB, Contamination, Heavy Metal Toxicity.
Frequently Asked Questions
What is the core focus of this research?
The research focuses on the identification and characterization of bacteria capable of oxidizing arsenite in arsenic-contaminated water sources within Uttar Pradesh, India, exploring their potential for environmental bioremediation.
What are the central themes covered?
The work covers arsenic geochemistry, the toxicity of inorganic arsenic species, microbial ecology in arsenic-rich environments, and the application of molecular techniques for bacterial identification and resistance gene detection.
What is the primary objective of this study?
The main goal is to isolate and molecularly characterize arsenite-oxidizing bacteria from five specific districts in Uttar Pradesh to assess their ability to reduce arsenic mobility and toxicity.
Which scientific methods are employed?
The study uses standard microbiological isolation techniques, atomic absorption spectrometry for arsenic detection, phenotypic and biochemical characterization, and molecular tools like PCR amplification and 16S rDNA sequencing.
What is discussed in the main part of the thesis?
The main part encompasses an extensive literature review on arsenic dynamics, detailed site descriptions and sampling methodology, followed by the presentation of experimental results concerning bacterial growth, resistance concentrations, and genetic profiling.
Which keywords best characterize this work?
The work is best defined by terms such as Arsenic bioremediation, microbial arsenic oxidation, groundwater contamination, and the characterization of novel bacterial strains like Rummeliibacillus and Brevibacillus species.
How does this study contribute to the existing body of knowledge regarding arsenic?
This study reports, for the first time, the presence of specific arsenite oxidase (aroA, aroB) and arsenite transporter (arsB, ACR3) genes in the isolated strains, highlighting their potential as a novel biological solution for treating contaminated water.
What is the significance of the findings for the region of Uttar Pradesh?
The findings provide a scientific basis for using native microbial communities in local bioremediation, which is critical for mitigating health risks associated with chronic arsenic exposure in rural drinking water supplies.
- Citation du texte
- PhD Bilal Ahmad Tantry (Auteur), 2017, Arsenic Oxidizing Microorganisms, Munich, GRIN Verlag, https://www.grin.com/document/415757
