Methane-eating bacteria discovered in the Western Ghats and Pune quarry

Scientists at the MACS Agharkar Research Institute (ARI) have reported the discovery of the first indigenous methane-eating bacteria, called methanotrophs, in rice fields and wetlands in western India.

Led by Dr. Monali Rahalkar, the team isolated and described a new genus and species of methanotrophs called Methylocucumis oryzae, which have the potential to address the coming challenges of climate change.

Methane, the second most important greenhouse gas, has a global warming potential 26 times higher than carbon dioxide. It is produced by methanogens in wetlands, rice fields, ruminants and landfills.

Methanotrophic or methane-oxidizing bacteria counteract this by oxidizing methane, thereby reducing its concentration in the atmosphere. These bacteria thrive in environments where both methane and oxygen are present, such as wetlands, rice fields, ponds and other bodies of water.

Dr. Rahalkar’s team discovered that Methylocucumis oryzae has a distinctive oval and elongated shape, earning it the nickname “methane-eating cucumber.”

This methanotroph was an important component of the quarry of Vetal Tekdi, a hill in Pune known for its unique flora and fauna. The quarry water, rich in invertebrates and molluscs, supports an active methane cycle enabled by these bacteria.

The discovery of Methylocucumis oryzae is particularly noteworthy because the species remains phylogenetically unique and no strains of this species have been reported or cultivated anywhere else in the world.

This bacterium is larger than most other bacteria, comparable to the size of small yeasts, and is strictly mesophilic in nature; it cannot grow at temperatures above 37 °C.

In recent years, Methylocucumis oryzae has been found to promote the growth of rice plants by inducing earlier flowering and increasing grain yield.

Experiments with the high-yielding rice variety Indrayani have demonstrated these advantages. However, the slow growth of this methanotroph poses a challenge for large-scale cultivation and biotechnological application.

The team’s findings were recently published in the Indian Journal of Microbiology, following previous reports in Microbial Ecology, Antonie van Leeuwenhoek, Frontiers in Microbiology and International Microbiology.

The discovery of this unique and possibly endemic methanotroph is crucial for future research and applications in the field of climate change.

Further improvements in culture conditions and large-scale cultivation could increase the practical utility of this organism in reducing methane levels in the atmosphere.