The Metabolism of Arsenite (Arsenic in the environment)

"Up to 200 million people in 70 countries are at risk from drinking water contaminated with arsenic, which is a major cause of chronic debilitating illnesses and fatal cancers. Until recently little was known about the mobility of arsenic, and how redox transformations determined its movement into or out of water supplies. Although human activities contribute to the release of arsenic from minerals, it is now clear that bacteria are responsible for most of the redox transformation of arsenic in the environment. Bacterial oxidation of arsenite (to the less mobile arsenate) has been known since 1918, but it was not until 2000 that a bacterium was shown to gain energy from this process. Since then a wide range of arseniteoxidizing bacteria have been isolated, including aerobes and anaerobes; heterotrophs and autotrophs; thermophiles, mesophiles and psychrophiles. This book reviews recent advances in the study of such bacteria. After a section on background geology and health issues the main body of the book concerns the cellular machinery of arsenite oxidation. It concludes by examining possible applications. Topics treated are: The geology and cycling of arsenic Arsenic and disease Arsenite oxidation: physiology, enzymes, genes, and gene regulation. Community genomics and functioning, and the evolution of arsenite oxidation Microbial arsenite oxidation in bioremediation Biosensors for arsenic in drinking water and industrial effluents""Arsenite contamination of drinking water is a major cause of chronic illness and mortality in many countries, but until recently little was known of the processes determining its movement and concentration. Bacterial oxidation of arsenite was first described in 1918 and thought to be a means of detoxification. It was not until 2000 that the first autotrophic arseniteoxidising bacterium was isolated and shown to gain energy from arsenite oxidation. Since then a wide range of such bacteria has been isolated and the literature on the topic has grown rapidly. This book reviews the new understanding of the diversity and abundance of such organisms, their role in arsenic cycling in the environment and their possible relations with arsenic-dependent diseases in humans"-- Read more... Abstract: "Up to 200 million people in 70 countries are at risk from drinking water contaminated with arsenic, which is a major cause of chronic debilitating illnesses and fatal cancers. Until recently little was known about the mobility of arsenic, and how redox transformations determined its movement into or out of water supplies. Although human activities contribute to the release of arsenic from minerals, it is now clear that bacteria are responsible for most of the redox transformation of arsenic in the environment. Bacterial oxidation of arsenite (to the less mobile arsenate) has been known since 1918, but it was not until 2000 that a bacterium was shown to gain energy from this process. Since then a wide range of arseniteoxidizing bacteria have been isolated, including aerobes and anaerobes; heterotrophs and autotrophs; thermophiles, mesophiles and psychrophiles. This book reviews recent advances in the study of such bacteria. After a section on background geology and health issues the main body of the book concerns the cellular machinery of arsenite oxidation. It concludes by examining possible applications. Topics treated are: The geology and cycling of arsenic Arsenic and disease Arsenite oxidation: physiology, enzymes, genes, and gene regulation. Community genomics and functioning, and the evolution of arsenite oxidation Microbial arsenite oxidation in bioremediation Biosensors for arsenic in drinking water and industrial effluents" "Arsenite contamination of drinking water is a major cause of chronic illness and mortality in many countries, but until recently little was known of the processes determining its movement and concentration. Bacterial oxidation of arsenite was first described in 1918 and thought to be a means of detoxification. It was not until 2000 that the first autotrophic arseniteoxidising bacterium was isolated and shown to gain energy from arsenite oxidation. Since then a wide range of such bacteria has been isolated and the literature on the topic has grown rapidly. This book reviews the new understanding of the diversity and abundance of such organisms, their role in arsenic cycling in the environment and their possible relations with arsenic-dependent diseases in humans"

Up to 200 million people in 70 countries are at risk from drinking water contaminated with arsenic, which is a major cause of chronic debilitating illnesses and fatal cancers. Until recently little was known about the mobility of arsenic, and how redox transformations determined its movement into or out of water supplies. Although human activities contribute to the release of arsenic from minerals, it is now clear that bacteria are responsible for most of the redox transformation of arsenic in the environment. Bacterial oxidation of arsenite (to the less mobile arsenate) has been known since 1918, but it was not until 2000 that a bacterium was shown to gain energy from this process. Since then a wide range of arsenite-oxidizing bacteria have been isolated, including aerobes and anaerobes; heterotrophs and autotrophs; thermophiles, mesophiles and psychrophiles. This book reviews recent advances in the study of such bacteria. After a section on background—geology and health issues—the main body of the book concerns the cellular machinery of arsenite oxidation. It concludes by examining possible applications. Topics treated are:

• The geology and cycling of arsenic
• Arsenic and disease
• Arsenite oxidation: physiology, enzymes, genes, and gene regulation.
• Community genomics and functioning, and the evolution of arsenite oxidation
• Microbial arsenite oxidation in bioremediation
• Biosensors for arsenic in drinking water and industrial effluents

1. Arsenic in the environment 23 1.1 Introduction 23 1.2 Chemistry and mineralogy of arsenic 23 1.3 Distribution of arsenic in the environment 27 1.4 Processes of arsenic cycling in the environment 32 3. Genotoxic and carcinogenic risk of arsenic exposure. Influence of interindividual genetic variability 63 3.1 Introduction 63 3.2 Carcinogenic risk 63 3.3 Genotoxic risk 65 3.4 Genetic polymorphisms affecting carcinogenic risk 65 3.5 Genetic polymorphisms affecting genotoxic risk 69 3.6 Conclusions 70 4. Overview of microbial arsenic metabolism and resistance 75 4.1 Introduction 75 4.2 Arsenic resistance 75 4.3 Arsenic in energy generation 76 7. Arsenite oxidase 101 7.1 Introduction 101 7.2 Characteristics of the arsenite oxidase 102 8. Microbial arsenic response and metabolism in the genomics era 118 8.1 Introduction 118 8.2 Descriptive and comparative genomics 118 8.3 High-throughput genomics reveal the functioning of microorganisms 123 8.4 Conclusions 129 Author index 200 Subject index 201 A 201 B 202 C 202 D 202 E 202 F 203 G 203 H 203 I 203 J 203 K 203 L 203 M 203 N 203 O 203 P 203 Q 204 R 204 S 204 T 204 U 204 V 204 W 205 X 205 Y 205 Arsenic in the Environment 206