India’s first cultures of indigenous methanotrophs ‘Methylocucumis oryzae’ from rice fields and wetlands have been isolated and described by the scientists from The MACS Agharkar Research Institute (an autonomous institute of Department Science and Technology)  

• Published In: The first novel methanotroph description from India, ‘a novel genus and species: Methylocucumis oryzae’ was published in the Indian Journal of Microbiology.
  • Earlier reports on the three strains of this methanotroph and its genome have been published in: Microbial Ecology, Antonie van Leeuwenhoek, Frontiers in Microbiology and International Microbiology.
• Found In: Methylocucumis Oryzae were found in a stone quarry in Pune, situated amidst the Vetal Tekdi or ARAI hill.
  • The team of scientists documented the abundance of methanotrophs in the water filled quarry, indicating that an active methane cycle operated in this unique habitat. 
• Methanotroph was added in transplanted rice plants in pot experiments using the local popular high yielding rice variety Indrayani.

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About Methylocucumis Oryzae

• Phylogenetically Unique: Methylocucumis oryzae remain phylogenetically unique as no strains have been reported or cultured from any other country or parts of the world.
• Appearance: The methanotroph had a characteristic oval and elongated shape, similar to that of a cucumber, and thus is also called ‘methane eating cucumbers’
• Size: It has a remarkably large size compared to other bacteria and is equal to the size of a small yeast (3-6 µm). 
• Temperature Range: it has a strict mesophilic nature and cannot grow above 37ºC while most of the other methanotrophs can tolerate or grow at 37ºC or even at 40ºC.

• Importance

  • Early growth and flowering: In pot experimental trials plant growth promotion in rice plants were seen with 31% higher yield. Early flowering (~ 17days earlier than the control plants) was seen when the rice plants were inoculated.
  • Methanotrophs have potential applications in carotenoid production due to their ability to synthesize carotenoids as part of their metabolic processes.
  • Industrial Applications: Methanotrophs can serve as a sustainable source for carotenoid production as chemical processes are economically unfeasible due to high production costs and produce harmful byproducts that pose risks to food safety
  • Abundance in Environment:  Nevertheless, there is evidence that this organism exists in nature in abundance in wetlands and rice fields and further optimization experiments can help us in developing environmental and biotechno-logical applications.
  • Oxidation of Methane: Methanotroph can restrict the net emission of Methane to the environment. These bacteria oxidize up to 20% of the produced methane in rice field habitats.

• Challenges

• • Slow Growth: Methylocucumis is a considerably slow-growing methanotroph and needs approximately 7–10 days to attain visible OD, and a maximum OD of ~ 0.4 is reached after 14 days of incubation
  • Isolation: Similar to a few other methanotrophs, it was initially very difficult to isolate Mcu in pure form 
  • Contamination: Mcu is prone to get contaminated with smaller motile rods, which probably grow on the exo-polysaccharides and metabolites released by Mcu. Due to the possibility of getting contaminated, Mcu has to be maintained under strict sterile conditions, and large-scale growth in a pure form is challenging.
  • Culturing:  Methanotrophs live in gradients of methane and oxygen in nature hence they do not grow easily on solid or liquid media. The basic requirement for culturing methanotrophs is the need for air-tight chambers desiccators or glassware that can be filled with methane and air

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