Bacteria that can degrade pesticide linked to Bhopal Gas tragedy


Researchers from the Indian Institute of Technology, Bombay have identified bacteria can reduce the amount of the pesticide carbaryl in soil, which was used in India for several years until it was banned last year. During the 1984 Bhopal gas tragedy, the gases that escaped and caused several thousand deaths and many lakh injuries was used to manufacture carbaryl. Carbaryl is known to be toxic to humans and has been banned in United Kingdom, Austria, Denmark, Sweden, Iran, Germany, and Angola. Prashant Phale and his team from IITB, along with Rakesh Sharma from Institute of Genomics Integrative Biology (CSIR-IGIB), Delhi, have identified a bacteria which can clean up this pesticide. The scientists found that three strains of the bacteria Pseudomonas can get rid of carbaryl. These bacteria can break down the pesticide three times faster than other similar bacteria which are known to break down carbaryl. “Carbaryl may stay back for years after the crop is harvested because it degrades slowly in the acidic soil as compared to alkaline soil. Also, repeated application of carbaryl in the fields increases its concentration to a level lethal for living beings”, said Phale in a release issued by the institute. The bacteria essentially uses the pesticide as food. The researchers speculate that the genes that allow the bacteria to breaking down carbaryl may have been acquired from other species of bacteria, through a process known as ‘horizontal gene transfer’, which is the transfer of genetic material between different organisms. Typically, genes are transferred within a species – from parent to offspring, during reproduction. The researchers have also understood how exactly the breakdown occurs. The researchers found that bacteria breaks down the pesticide into an intermediate product called 1-naphthol, which itself is highly toxic. To survive the 1-naphthol, the bacteria keeps it in a chamber outside the main body, and then slow slowly lets it in so that it can be broken down. An advantage of the bacteria is that they are not genetically modified organisms, and so there are no restrictions on their use. The bacteria can also be used to treat waste water and effluents from industries using or producing carbaryl or 1-naphthol. The findings were published in the journal Applied and Environmental Biology.

The Economic Times, November 2019