Researchers at IIT-Bombay have identified two genera of bacteria, Pseudomonas and Acinetobacter, that have great potential in agriculture. 

These groups of bacteria can break harmful aromatic (or ring-shaped) compounds that enter the soil through insecticides, herbicides and industrial effluents into useful nutrients for plants. 

Aromatic compounds like naphthalene, benzoate and phthalates are used to make cosmetics, textiles, food preservatives and pesticides. 

They are useful, for sure, but turn into a problem when they enter the soil. 

They hinder seed germination, inhibit plant growth and, through the plants, poison us. Removing them from the soil is neither easy nor cheap — they are stable compounds that do not react easily with added substances; they are also typically not soluble in water and cannot be drained off. 

But they also happen to be bacteria food.

Dual action

Prof Prashant Phale, from the Department of Biosciences and Bioengineering at IIT-Bombay, and Sandeesh Papade, research scholar, decided to approach the problem from a different angle — recruiting bacteria and letting them loose in the soil. 

The bacteria broke down the undesirable compounds into simpler compounds — much like cutting long chains into small bits. In the process, they released nutrients useful to plants, such as phosphorus and potassium. While the aromatic compounds are insoluble in water, the released nutrients are soluble and can be absorbed by plants. “They also produce substances called siderophores, which help plants absorb iron in nutrient-limited environments,” notes an article on the IIT-Bombay website. Further, the bacteria also contribute to plant growth and health by producing the growth hormone indoleacetic acid. 

“While these bacteria are cleaning the soil, they are also helping plants grow healthier and more robust by fertilizing the soil and improving soil health,” Prof Phale says in the article. 

Interestingly, when these two groups of bacteria were used together, they produced even more beneficial results. “The consortium displayed strong plant growth promoting as well as phytoprotection ability against toxicity of aromatics,” the researchers say in a paper published in Environmental Technology & Innovation. 

The ability of the two genera to co-exist is notable because you can then make biofertilizer-cum-biocontrol formulations. 

Phale notes that these bacteria can eat up harmful fungi too. In the future, researchers want to test how these bacteria can benefit plants during droughts and other environmental stress conditions. 

“The assistive eco-physiological traits (biofilm, resistance to fusaric acid and salinity tolerance) displayed by strains indicated their better adaptability, survival and niche colonisation behaviour under environmental extremities,” the paper says.