~ 2049 ~ Journal of Pharmacognosy and Phytochemistry 2020; 9(4): 2049-2060 E-ISSN: 2278-4136 P-ISSN: 2349-8234 www.phytojournal.com JPP 2020; 9(4): 2049-2060 Received: 19-05-2020 Accepted: 20-06-2020 Kusum Dua Department of Microbiology, Punjab Agricultural University, Ludhiana, Punjab, India Neelam Joshi Department of Microbiology, Punjab Agricultural University, Ludhiana, Punjab, India Corresponding Author: Kusum Dua Department of microbiology, Punjab Agricultural University, Ludhiana, Punjab, India Chlorpyrifos: It’s bioremediation in agricultural soils Kusum Dua and Neelam Joshi DOI: https://doi.org/10.22271/phyto.2020.v9.i4ab.12058 Abstract Organophosphorous pesticides are widely used in agriculture to control major insect pests. Chlorpyrifos is one of the major organophosphorous pesticides which have been used since 1960s, to control insects including termites, beetles. The widespread use of these pesticides is hazardous to the environment and also toxic to mammals. Moreover, given the persistence and toxicity of chlorpyrifos towards life forms, it is essential to remove the same from the environment. Among many physical, chemical, and biological methods for the removal of organophosphorus pesticides from ecosystems, biodegradation is preferred because of its environmental compatibility and cost-effectiveness. Considering the havoc created by chlorpyrifos in food chain as well as in the ecosystem, it is urgent to develop a bioremediation technology for minimising its side effects. Keeping this in view, the present article is aimed to provide a detailed study on chlorpyrifos and witness the significant research conducted by various researchers for its bioremediation. Keywords: chlorpyrifos, biodegradtion, bioremediation, organophosphorous pesticides Introduction Bioremediation is the use of living organisms to minimize or eliminate the environmental hazards resulting from accumulation of toxic chemicals and other hazardous wastes. It is an innovative technology that is frequently being chosen for the cleanup of sites on the National Priority List (NPL). Recent research is expanding the capabilities of this technology, which, along with its generally lower cost, has led to bioremediation becoming an increasingly attractive cleanup technology. Bioremediation is a promising alternative to physico-chemical methods of remediation, because it is less expensive and can selectively achieve complete destruction of organic pollutants (Alexander 1999) [8] . The use of microorganisms for the degradation and detoxification of numerous toxic xenobiotics, especially pesticides, proved to be an efficient tool to decontaminate the polluted sites in the prevailing environment (Mervat 2009) [63] . Bioremediation methodology to treat xenobiotics such as pesticides in soil has gained considerable attention owing to its ecofriendliness and has been employed successfully in many countries (Enrica 1994, Ritmann et al. 1988) [26, 82] . Pesticides in soil and water can be biodegraded and is the primary mechanism of pesticide breakdown and detoxification in many soils (Surekha et al. 2008) [96] . Conventional approaches (e.g. landfilling, recycling, pyrolysis and incineration) for the remediation of contaminated sites are inefficient, costly and may lead to the formation of several toxic intermediates (Sayler et al. 1990) [83] . Thus, biological decontamination methods are preferable to conventional approaches because, in general, microorganisms degrade numerous environmental pollutants without producing toxic intermediates (Pieper and Reineke 2000, Furukawa 2003) [73, 30] . Biodegradation and bioremediation are matching processes to an extent that both of these are based on the conversion or metabolism of pesticides by microorganisms. The difference between these two is that, the biodegradation is a natural process whereas bioremediation is a technology. In bioremediation, we use microbes to degrade the pesticides in situ. A successful bioremediation technique requires an efficient bacterial strain that can degrade largest pollutant to minimum level. Adequate rate of biodegradation is required to attain the acceptable level of pesticide residues or its metabolites at contaminated site in a limited time frame. Degradation of endosulfan by three bacterial species namely Staphylococcus sp., Bacillus circulans-I, and Bacillus circulans-II, was studied by Kumar and Philip (2006) [49] both in mixed isolate and pure isolate. In mixed isolate, after four weeks of incubation degradation of 71.82 ± 0.2 per cent and 76.04 ± 0.2 per cent of endosulfan in aerobic and facultative anaerobic conditions, respectively was observed. In pure isolate a degradation potential of 93.3