Review Environmental Sciences Genetically engineered organisms for bioremediation of pollutants in contaminated sites Md. Abul Kalam Azad • Latifah Amin • Nik Marzuki Sidik Received: 2 October 2013 / Accepted: 7 December 2013 / Published online: 29 January 2014 Ó Science China Press and Springer-Verlag Berlin Heidelberg 2014 Abstract Environmental pollution is a major problem which affects biodiversity, public health and ecosystems worldwide. This issue cannot currently be solved using conventional technology because these treatments are expensive, ineffective and time consuming. Conventional methods focus unduly on the separation, rather than the destruction of contaminants. The use of genetically engi- neered organisms for bioremediation would be an envi- ronmentally-friendly and cost-effective alternative for the management and remediation of pollutants in contaminated sites. Different types of genetically engineered microbes have been developed through recombinant DNA and RNA technologies, these have been utilized for the removal of heavy metals and toxic substances from contaminated sites. Transgenic plants can also mobilize or degrade chlorinated solvent, xenobiotic compounds, explosives and phenolic substances. A symbiotic relationship between genetic engineered microbes and transgenic plants can enhance the effectiveness of bioremediation of contaminated sites. This review examines recent developments in the use of genetically engineered microbes and transgenic plants for the bioremediation of contaminated sites. This review will also identify the environmental factors which influence bioremediation by genetically engineered microbes and transgenic plants as well as suggesting future directions for research in these areas. Keywords Bioremediation Á Pollutants Á Genetically engineered microbes Á Transgenic plants The extraction of natural resources and rapid industriali- zation has created contamination and pollution, on a grand scale, worldwide. Huge amounts of toxic, chemical sub- stances have been dispersed on thousands of contaminated sites throughout the globe, with ramifications for human health and the environment. The increases in heavy industry and mining have resulted in the environment being contaminated with xenobiotic compounds. Xenobiotic compounds can harm environmental ecosystems, directly, by their inherent toxicity [1]. Soil may become contami- nated through emissions from industrial sources, mining, landfills, farming, coal residues, petrochemical spillages, atmospheric deposition and the disposal of metallic waste. Metals such as lead (Pb), chromium (Cr), arsenic (As), zinc (Zn), cadmium (Cd), copper (Cu), mercury (Hg) and nickel (Ni) are responsible for the contamination of soil [2]. Groundwater may be contaminated via waste from storage tanks, septic systems, hazardous waste sites, landfills, fer- tilizers and the use of pesticides. Contaminated soil and water are major problems for human health, plants, wildlife and the environment worldwide. The remediation of con- tamination is complicated by the variety of chemical structures, bioavailability, toxicity and the recalcitrance of contaminants [3]. Great difficulties are experienced in attempts to remove heavy metals from contaminated sites Md. A. K. Azad (&) Á L. Amin Centre for General Studies, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia e-mail: azad.dae@gmail.com L. Amin e-mail: nilam@ukm.my Md. A. K. Azad Department of Agricultural Extension, Khamarbari, Farmgate, Dhaka 1215, Bangladesh N. M. Sidik Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor, Malaysia e-mail: nms@ukm.my 123 Chin. Sci. Bull. (2014) 59(8):703–714 csb.scichina.com DOI 10.1007/s11434-013-0058-8 www.springer.com/scp