Insights into Methylocucumis oryzae, a Large-sized, Phylogenetically Unique Type Ia Methanotroph with Biotechnological Potential

Abstract

The cultivation of microorganisms is important as it provides us an opportunity to explore the characteristics that can be used for a variety of applications. Methanotrophs oxidize methane and are one of the most challenging organisms to culture. In 2018, we cultured one of the largest methanotrophs within the gammaproteobacterial group (Type Ia), a novel genus and species, Methylocucumis oryzae, with large peculiar, elongated oval (cucumber-shaped) cells (~ 3–6 µm length × 1.5 µm breadth). We have described three strains of Methylocucumis oryzae (abbreviated as Mcu or Mcu oryzae) isolated from two flooded rice fields and recently from a stone quarry in Pune, all three locations are in Maharashtra state, Western India. Mcu is a mesophile and prefers lower temperatures for growth in the range 20–28 °C and does not grow above 37 °C. No other species of Methylocucumis have been reported from any other country and Mcu oryzae appears to be phylogenetically unique after 6 years of its initial report. Though the culture has certain challenges to grow on a larger scale due to its slow growth rate, it might have significant potential in methane mitigation, plant growth promotion, carotenoid production, etc. awaiting more detailed studies on this rare organism. Further optimization experiments to grow Mcu in large quantities might help us in developing environmental and biotechnological applications.