Indian Institute of Technology, Bombay, is not just home to great science minds, it also harbours some unique microorganisms. Recently, researchers have identified a soil bacterial strain from the campus that helps in “complete remediation” of the carbaryl pesticide.
Carbaryl pesticide continues to be used in the agricultural sector in spite of experimental studies in laboratory animals suggesting it to be a probable carcinogen to humans. Carbaryl is also persistent in nature leading to pollution of both soil and water ecosystems.
The newly isolated bacterial strain utilises the pesticide as its source of carbon and nitrogen for its growth. The team was also able to identify the genes responsible and the metabolic pathway involved in the complete metabolism and bioremediation process.
The bacterial strain, whose species is yet to be identified, comes under the Pseudomonas genus and was able to grow well on medium supplemented with very high concentration of carbaryl.
The bacterial enzyme ‘carbaryl hydrolase’ acts on carbaryl and generates ‘1-naphthol’ and ‘methylamine’. While 1-naphthol is used as a carbon source, methylamine is used as the nitrogen source. Though many microbes like Rhodococcus, Arthrobacter have been previously reported to degrade carbaryl, the Pseudomonas strain recently reported in Applied and Environmental Microbiology was found to be more efficient. It could completely degrade the pesticide in 12-13 hours. Researchers say that this is four to five times faster than other bacterial strains reported earlier.
A study of the genome showed that it has special genes responsible for carbaryl degradation. The bacterium might have acquired these genes from other related microbes that are capable of breaking down hazardous compounds. The team has recently published a review paper in the journal Genes explaining this process of movement of genetic material between organisms. This is called ‘horizontal gene transfer’ and is different from vertical gene transfer from parent to offspring.
Natural laboratory
“Nature acts as a laboratory on its own. Organisms in an ecosystem interact with each other and exchange genetic material for their benefit and survival,” explains Dr. Prashant S. Phale in a release. He is from the Department of Biosciences and Bioengineering at IITB and is the corresponding author of the study.
“The bacteria are able to adapt themselves to recently introduced pesticides too. They do this by acquiring genes through horizontal gene transfer and also evolving some existing genes to perform new functions,” adds Dr. Rakesh Sharma, a collaborator and one of the co-authors from the CSIR-Institute of Genomics and Integrative Biology, New Delhi, India.
