In the past few decades, increased awareness of environmental pollution has led to the exploitation of microbial metabolic potential in the construction of several genetically engineered microorganisms (GEMs) for bioremediation purposes. At the same time, environmental concerns and regulatory constraints have limited the in situ application of GEMs, the ultimate objective behind their development. In order to address the anticipated risks due to the uncontrolled survival/dispersal of GEMs or recombinant plasmids into the environment, some attempts have been made to (...) construct systems that would contain the released organisms. This article discusses the designing of safer genetically engineered organisms for environmental release with specific emphasis on the use of bacterial plasmid addiction systems to limit their survival thus minimizing the anticipated risk. We also conceptualize a novel strategy to construct “Suicidal Genetically Engineered Microorganisms (SGEMs)” by exploring/combining the knowledge of different plasmid addiction systems (such as antisense RNA‐regulated plasmid addiction, proteic plasmid addiction etc.) and inducible degradative operons of bacteria. BioEssays 27:563–573, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

The global production of radioactive wastes is expected to increase in the coming years as more countries have resorted to adopting nuclear power to decrease their reliance on fossil-fuel-generated energy. Discoveries of remediation methods that can remove radionuclides from radioactive wastes, including those discharged to the environment, are therefore vital to reduce risks-upon-exposure radionuclides posed to humans and wildlife. Among various remediation approaches available, microbe-mediated radionuclide remediation have limited reviews regarding their advances. This review provides an overview of the sources (...) and existing classification of radioactive wastes, followed by a brief introduction to existing radionuclide remediation (physical, chemical, and electrochemical) approaches. Microbe-mediated radionuclide remediation (bacterial, myco-, and phycoremediation) is then extensively discussed. Bacterial remediation involves biological processes like bioreduction, biosorption, and bioprecipitation. Bioreduction involves the reduction of water-soluble, mobile radionuclides to water-insoluble, immobile lower oxidation states by ferric iron-reducing, sulfate-reducing, and certain extremophilic bacteria, and in situ remediation has become possible by adding electron donors to contaminated waters to enrich indigenous iron- and sulfate-reducing bacteria populations. In biosorption, radionuclides are associated with functional groups on the microbial cell surface, followed by getting reduced to immobilized forms or precipitated intracellularly or extracellularly. Myco- and phycoremediation often involve processes like biosorption and bioaccumulation, where the former is influenced by pH and cell concentration. A Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis on microbial remediation is also performed. It is suggested that two research directions: genetic engineering of radiation-resistant microorganisms and co-application of microbe-mediated remediation with other remediation methods could potentially result in the discovery of in situ or ex situ microbe-involving radioactive waste remediation applications with high practicability. Finally, a comparison between the strengths and weaknesses of each approach is provided. (shrink)

In this essay, I explore non-human multispecies interactions in soils polluted by electronic waste and subsequently bioremediated by plants and microbes. I argue that regenerative transformation in polluted soil environments is principally through microbial degradation, a significant process for survival amidst disaster. In doing so, I combine two separate research areas – the materiality of electronic waste and of soils – thus contributing to theorization on the persistent problem of anthropogenically polluted soils. I do so by examining the process of (...) bioremediation, which ties anthropogenic pollution with underground soil processes, notably those that occur at the soil interface surrounding plant roots, the rhizosphere. Using empirical examples from scientific literature on the bioremediation of electronic waste-contaminated soils in China, I demonstrate that degradation, symbiosis, and sequestration are instrumental processes in polluted soils. The micro-scaled perspective of these relational processes and their toxic alterlives contributes to materialist, chemosocial understandings of toxic and polluted environments. (shrink)

In this article, I examine the rhetoric of democratic science within the field of synthetic biology. The still emerging field of synthetic biology claims to be a new kind of science based on the promises of affordable medicines, environmental bioremediation, and democratic, do-it-yourself science practices. I argue that the formation of a more democratic, DIY portion of this field represents an intervention into ethics debates by becoming “the proper informed public.” Through an analysis of twelve DIY and community-based synthetic (...) biology organizations’ websites, I found that democratic science was presented as a novel, progressive approach to science that addresses ethical concerns and at the same time produces better scientific results. In part, these claims were made possible through a reconfiguring of the boundaries between Science and the Public where scientists lay claim to solidarity with the public at large in opposition to traditional biosciences and Big Bio. My research suggests that the superficial use of the language of rights and democracy relegitimizes the primacy of scientific discovery to solve societal problems. I further suggest that by becoming the proper informed public, ethical challenges from publics critical of genetic sciences may become delegitimized. (shrink)

The objective of this study was to correlate the presence of arsenic in roots and stems of Brachiaria humidicola cv. humidicola (Rendle) Schweick grown in cattle areas of the San Jorge subregion and the population density of endophytic bacteria in roots and foliage with the presence of this metal. Samples of soil, roots and stems of B. humicola grass were collected and characterized for arsenic concentration in roots and foliage and the presence of endophytic bacteria (CFU/g tissue). The results show (...) the presence of arsenic concentrations in roots and stems above the values established at national and international level. Likewise, the presence of endophytic bacteria was found in the roots and foliage of B. humidicola, which may be contributing to the remediation and reduction of arsenic concentration from the roots to the foliage. This is the first study correlating the presence of arsenic and endophytic bacteria on cattle farms with B. humicola and the possible role of these bacteria in contributing to bioremediation of this metal in the soil and within the tissues of the pasture species. (shrink)

E-waste, also known as waste from electrical and electronic equipment, is a solid waste that accumulates quickly due to high demand driven by the market for replacing newer electrical and electronic products. The global e-waste generation is estimated to be between 53.6 million tons, and it is increasing by 3–5% per year. Metals make-up approximately 30% of e-waste, which contains precious elements Au, Ag, Cu, Pt, and other high-value elements, valued at USD 57 billion, which is driving the e-waste recycling (...) industry. It is noteworthy that the recycling of precious elements from e-waste has emerged as a profitable enterprise in several parts of developing nations. E-waste contains 50–100 times higher levels of precious metals compared to natural ores, making it suitable for mining. E-waste recycling in developing nations, mostly occurs through the informal sector comprising manual collection, crushing, segregation and selling of precious elements, such as Au, Ag, Cu, Pb, Pt, and other rare elements (Nd, In, and Ga). The organized sector, on the other hand, mostly employs mechano-chemical methods, such as pyrometallurgy, hydrometallurgy, and bio-hydrometallurgy, which have serious environmental consequences. Both the informal and formal sectors of e-waste processing lead to the leaching of toxic elements into groundwater and soils. Owing to the lesser efficiency of greener technologies, such as phytoremediation and bioremediation, their use in precious metal extraction is very limited. However, this review explores several hyper-accumulating and tolerant plants viz. Brassica juncea and Berkheya coddii, which holds great potential in phytomining of precious metal from e-waste. Thus, the state of the art in precious metal extraction from e-waste as well as the advantages and disadvantages of different metal extraction technologies has been reviewed. (shrink)