The secrets of low-methane emitting sheep

Dr Sandeep Kumar

Dr Sandeep Kumar has been looking at one of the world’s most pressing issues -  greenhouses gases, and one bacterium that might hold the key to reducing emissions.

Graduating yesterday in the Manawatū, Dr Kumar arrived in New Zealand in the summer of 2011 as a LEARN scholar from India to work in AgResearch’s rumen microbiology team. 

“In the beginning, I was bit hesitant about coming to New Zealand, as I never travelled overseas before, but once I arrived, everything went very well. I made many friends (covering from more than 20 different countries) which helped me to get through the challenging PhD journey.”

“I came from a small village situated in the eastern part of India. Growing up in the village provided me an initial understanding of agriculture and its impact on society, which gave me a desire to learn more about it. I moved to many cities in India to get better education and in the process my journey brought me here to Palmerston North.”

After briefly returning to India, Dr Kumar came back to start a PhD in 2013 thanks to funding from the Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC) and a Walsh fellowship from Teagasc (Ireland).

For this PhD, Dr Kumar investigated sheep that naturally produce less methane, and the key bacteria associated with these sheep. 

“Methane is a by-product of feed digestion that contributes about one-third of New Zealand's anthropogenic greenhouse gases,” Dr Kumar says. “In the rumen [the first stomach of a ruminant], nearly all bacteria exist by fermenting the plant material ingested by the animal. There is a rather large bacterium found to be abundant in the rumen of naturally low-methane emitting sheep called Quinella, I wanted to understand why large populations of Quinella are associated with the rumens of sheep producing less methane.”

“The problem is that the few published attempts that define its metabolism were contradictory, so we needed to study it further to work out its role in low methane emissions.”

Quinella, an iconic bacterium first seen in sheep rumen contents in 1913, cannot be cultured, so Dr Kumar had to develop a way to generate preparations of rumen contents highly enriched with Quinella, which he did so by exploiting the physical size of this bacterium. By analysing four Quinella genomes assembled from DNA extracted from rumen contents, he found that Quinella has all the genes needed to produce propionate and acetate as well as lactate. 

“Results showed that it produced little or no hydrogen, a major precursor for methane, explaining why greater abundances of these bacteria leads to lower methane emissions.” 

Additionally, Dr Kumar found that there were multiple species of the genus Quinella, where previously only Quinella ovalis had been recognised. “As a microbiologist it is quite challenging to work with unculturable bacteria but at the same time it is rewarding as well when you successfully answer the question. In my PhD that is what exactly happened, as even after an unsuccessful isolation attempt, with the help of molecular biology and bioinformatics tools and software, I was able to construct the physiology of Quinella.” 

Dr Kumar conducted much of his research at the AgResearch Grasslands campus, supervised by Dr Peter Janssen (AgResearch), Dr Mark Patchett (Massey University) and Dr Sinead Waters (Teagasc). Other interesting aspects of its metabolism were also found during Dr Kumar’s work, but those will be for others to investigate. He has now accepted a postdoctoral scientist position in AgResearch, where he will be applying his microbiological skills to study bacterial endophytes.

Outside of his busy scientific life he is a passionate cricketer, loves playing squash, volleyball, and badminton and he says he would like to continue to explore more of New Zealand’s natural beauty.

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