Efficacy of an Indigenously Isolated Rice Field Methanotroph as a Potential Bio-Inoculant for Promoting Rice Plant Growth

Methanotrophs offer promising avenues for sustainable agriculture and climate mitigation. This study evaluates the efficacy of indigenously isolated methanotrophs, particularly Methylomonas Kb3, as bioinoculants in rice cultivation. Kb3-treated plants exhibited early flowering, increased height, and a grain yield up to 17% higher than that of untreated controls. A mixed inoculation of Methylomonas and Methylomagnum resulted in a 15% increase in yield, indicating limited synergistic benefit. The root-dipping method during transplantation proved to be a practical and scalable inoculation technique for farmers. Genomic analysis revealed that Methylomonas Kb3 harbours genes associated with nitrogen fixation and resistance to heavy metals and antibiotics, potentially underpinning its agronomic performance. Beyond yield enhancement, the application of methanotrophs may contribute to reduced methane emissions in flooded paddy systems, offering dual benefits for both productivity and environmental sustainability. These findings warrant multilocation trials to validate efficacy across diverse agro-climatic zones and support the development of climate-smart biofertilizer strategies.