Green revolution has blessed humanity with newer production methods in the field of agriculture and granted hopes for food security. The introduction of pesticides and fertilizers to the field has been a double edged sword which was beneficial in increasing the productivity but at the same time posed serious ecological concerns.
DDT have been banned worldwide for agricultural uses in 2001 by the Stockholm convention on Persistant Organic Pollutants due to its hazardous effects. Similar fate to the BHC has given rise to the need for more effective and safe alternatives to be used as pesticides in agricultural field.
Endosulfan has been the new entrant in the organochlorine pesticides which has been widely used since the last three decades. The pesticide is used extensively as an insecticide for Flea beetle, peach tree borer, cabbageworm, Colorado potato beetle, etc. It is also an effective acaricide which can destroy mites in cotton, paddy, oilseeds, sorghum and coffee. It is also used as wood preservative αand for control of garden pests. However, it is highly toxic and therefore classified as highly hazardous chemical by USFDA. The neurotoxic ability of endosulfan in insects and humans has been said to the the primary cause of widespread occurrence of endocephalis in Kerala, India which has ignited the necessity of its ban.
Endosulfan is a widely used pesticide which has emerged as a major environmental threat due to its long shelf life especially its sulphate metaboliten . The pesticide has been incidental in causing severe cerebral damages in affected areas. This has resulted in a necessity for a low cost, environment friendly method for its removal from nature.
Ideal candidate has been found in the soil bacterium which was isolated by nutritional selection with a medium containing endosulfan as the only source of sulphur. Researchers at the Centre for Advanced Studies in Zoology, Jaipur, India has been able to isolate and enrich the bacterial culture which was able to degrade not only endosulfan but also endosulfan sulphate. The strain was found to metabolize endosulfan and its toxic form endosulfan sulphate to non toxic metabolites such as endodiol and endosulfone lactone.
The degradation was found to be relatively rapid ( maximum 7 days) and efficient upto 94.2%. The soil isolate was characterized to be a new strain of Bacillus Sublitis using physiological, morphological, biochemical as well as 16s rRNA sequencing methods. The bacterium was able to degrade both the isomers of endosulfan (α and β).
The metabolites being non toxic, the isolate is a promising candidate for bioremediation of endosulfan affected areas. Further scaling up and genetic studies could prove more promising ways to tackle the issue.
About Author / Additional Info:
1. Ajit Kumar et al; Isolation and characterization of a Bacillus subtilis strain that degrades endosulfan and endosulfan sulphate; 3 Biotech; DOI 10.1007/s13205-013-0176-7