Phosphorus plays an important role in regulating various metabolic pathways. It is an essential macronutrient for plant growth and development and an integral component for biomolecules such as DNA and RNA.
Phosphorus is abundant in soil – but in insoluble forms such as aluminium or iron phospates. However, there are bacteria that can solubilise such phosphates. Instead of processing rock phosphate industrially to convert it into soluble phosphate fertilisers and then transporting it to farms in different parts of the country, one could use these bacteria to help solubilise phosphate available locally in soils to improve crop growth and productivity.
This thought provoked Vimala Prakash and colleagues from the IPL Biologicals Limited, Gurugram, to set out on a mission to isolate and identify potential phosphate solubilising bacteria.
They went to a rock phosphate mine in Jhamarkotra, near Udaipur, Rajasthan and dug about 15 centimetres into the barren soil to collect samples. The bacteria in such soils have greater chances of possessing phosphate solubilising enzymes, they reasoned. In fact, they may also have other useful properties such as solubilising potassium and zinc, other essential minerals for life. They might even produce siderophores, proteins that chelate heavy metals.
The researchers isolated and cultured bacteria from their samples. Using serial culturing, they found 137 distinct bacterial colonies. Based on the characteristics of the colonies, the researchers selected ten for further tests.
They screened the bacteria for their ability to solubilize phosphate, potassium, and zinc as well as to produce siderophores. Using biochemical assays and a variety of media containing insoluble zinc, potash, phosphate or heavy metals, they homed in on the bacterium with the highest plant-growth promoting properties.
Comparing the 16S rRNA gene sequence of the isolate with sequences available in public databases, the researchers identified it as Bacillus altitudinis – a bacterial species first discovered at high altitudes.
Now, the researchers confronted the next question: does this bacterium really improve plant growth?
To find out, the team grew maize in pots. They washed maize seeds and dipped them in culture media containing B. altitudinis. The seeds thus coated with the bacillus grew significantly faster. The shoots were 155 percent longer and roots 45 percent longer than those of plants from uncoated seeds. The weight of plants from coated seeds also increased significantly.
“This bacterium has the potential to be used as a biofertiliser,” says Sonia Arora, IPL Biologicals Limited, Gurugram.
“There are other bacteria that can solubilise phosphorus. But the strain we isolated does more by solubilising potassium and zinc besides helping plants to resist heavy metals’, adds Gaurav Sood.
“The strain we isolated can probably contribute towards sustainable agriculture practices and reduce the costs of fertilisation for the farmers”, suggests Pallavi Gaur, her colleague.
“We will, of course, have to use field trials to demonstrate safety and efficacy of Bacillus altitudinis before it is used in agriculture”, adds their senior colleague, Vimala Prakash.
Time for progressive farmers to get involved in scientific experiments!
Geomicrobiology Journal, (1521-0529, 2022);
DOI: 10.1080/01490451.2022.2155889
Reported by Amit Kumar
Sathyabama Institute of Science and Technology, Chennai
*This report was written in a workshop on science writing conducted by Current Science.
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Interesting and informative.
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Reblogged this on Marine Biology Lab @ Sathyabama, Chennai.
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