INDIA’S FIRST CULTURES OF INDIGENOUS METHANOTROPHS

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Context

• Agharkar Research Institute has made a groundbreaking discovery by isolating and describing India’s first cultures of indigenous methanotrophs.

 Details

• These methanotrophs were primarily sourced from rice fields and wetlands in Western India.
• The team identified a novel genus and species, Methylocucumis oryzae, notable for its oval, cucumber-like shape, hence the nickname ‘methane-eating cucumbers.’

 Background

Methanogens

• Methanogens are microorganisms whose metabolism generates methane.
• All methanogenic organisms belong to the Domain Archaea, phylum Euryarchaeota.
• Methanogenic archaea, also referred to as methanobacteria, are the living beings most sensitive to oxygen which is why they only develop in anaerobic and reducing environments.
• Despite this limitation, their ecological niches are widely distributed: aquatic sediments (marshes, swamps), stagnant soil (peat bogs, ricefields), marine geothermal vents, the digestive tract of certain animals

 Methanotrophs

• Methanotrophs are organisms which are able to obtain energy by oxidizing methane (CH4).
• Methane, found widely in nature, is produced in strict anaerobic conditions by methanogenic Archaea.
• It is the main gas in anoxic muds, marshes, lakes, rice paddies, and landfills.
• Methane is the major constituent of natural gas and is also present in many coal formations. It can be used as an electron donor by methanotrophic bacteria.
• Methanotrophs can also use other one-carbon compounds as a source of energy and carbon.
• Most of the known methanotrophs are aerobic, although, recently, methanotrophic activities in anoxic environments have been detected.
• All methanotrophs possess a specific enzyme, methane monooxygenase, which can insert an oxygen atom into the methane molecule generating methanol.
• The oxygen requirement for the oxygenation of methane explains their obligate aerobic character.

Recent Discovery: Importance of Methanotrophs

• The world is grappling with global warming and climate change, with methane emerging as a significant concern.
• Methane, the second most crucial greenhouse gas, has a global warming potential 26 times greater than carbon dioxide.
• Sources of methane include wetlands, ruminants, rice fields, and landfills, where methanogens produce this gas.
• In response, methanotrophs, or methane-oxidizing bacteria, play a crucial role in mitigating methane by oxidizing it, converting it into carbon dioxide and water.

Unique Characteristics and Applications

Methylocucumis oryzae has several unique traits:

• Morphology and Size: This methanotroph is larger than most bacteria, comparable in size to a small yeast (3-6 µm).
• Temperature Sensitivity: It is strictly mesophilic, thriving only up to 37ºC, unlike other methanotrophs that can tolerate higher temperatures.
• Colony Appearance: It forms light pale pink colonies and has a genome indicative of a carotenoid pathway.

Environmental and Agricultural Impact

• Recent studies revealed that Methylocucumis oryzae is a significant component of the methane cycle in a stone quarry in Pune.
• Additionally, it was found to promote rice plant growth by inducing early flowering and increasing grain yield.
• Pot experiments using the Indrayani rice variety demonstrated the methanotroph’s beneficial effects.

Challenges and Future Directions

• Despite its potential, the slow growth rate of Methylocucumis oryzae limits large-scale cultivation, which is necessary for broader applications. However, its abundance in wetlands and rice fields suggests it is performing its methane-mitigating role effectively.
• Further research and improvements in culture conditions could enhance its applications in mitigating climate change.

MUST READ ARTICLE: RISING METHANE AND EARTH’S CLIMATE TRANSITION:  https://www.iasgyan.in/daily-current-affairs/rising-methane-and-earths-climate-transition

MUST READ ARTICLE: Methane Green House Gas: https://www.iasgyan.in/daily-current-affairs/methane-green-house-gas#:~:text=The%20microbes%20that%20produce%20methane,sediments%20of%20lakes%20and%20oceans. 

PRACTICE QUESTION Q. Discuss the impact of rising methane levels on Earth's climate transition. Include the sources of methane, its role as a greenhouse gas, and potential mitigation strategies.

SOURCE: PIB