Analysis of the microbial consortia of methane-oxidizing bacteria in rice with the aim of reducing methane emissions and promoting rice growth

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K20570
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0601:Agricultural chemistry and related fields
• Research Institution: Nagoya University
• Principal Investigator: Shinjo Rina 名古屋大学, 生命農学研究科, 助教 (10908841)
• Project Period (FY): 2021-08-30 – 2024-03-31
• Keywords: メタン酸化細菌 / イネ / コンソーシアム

Outline of Final Research Achievements

Aerobic methane-oxidizing bacteria (MOB) are important in mitigating methane emissions from paddy fields. This study aims to clarify the microbial structure of heterotrophic bacteria that coexist with MOB in rice-derived enrichment cultures and to investigate the effects of these heterotrophic bacteria on methane oxidation. Twelve strains of heterotrophic bacteria, classified into seven genera (Acidovorax, Ancylobacter, Caulobacter, Methylobacillus, Phenylobacterium, Roseomonas, Segnochrobactrum), were isolated from enrichment culture. In vitro cocultures with the heterotrophs Acidovorax sp., Ancylobacter sp., Caulobacter sp., Roseomonas sp., and Segnochrobactrum sp., showed that the methane oxidation of Methylomonas sp. was significantly promoted. However, co-inoculation of MOB (Methylomonas sp.) and Ancylobacter sp. to rice tended to promote rice growth but did not affect methane oxidation activity. Further analysis is needed to verify the effect of co-inoculation on rice.

Free Research Field

農学

Academic Significance and Societal Importance of the Research Achievements

水田からのメタン排出の削減に向けてメタン酸化細菌の活用が期待される一方で、その単離は数例に留まっており、農業現場での応用利用は進んでいない。その要因のひとつとしてメタン酸化細菌の純粋培養の難しさがある。メタン酸化細菌と従属細菌の分離は非常に困難であり、その純化には集積培養や限界希釈法を繰り返し数ヶ月かかることもある。本研究はそのメタン酸化細菌と従属細菌の強固な結びつきを逆手にとり、菌間相互作用の解明、さらにはイネにおけるメタン生成量の削減と生育促進の実現を目指すものである。本研究で得られる成果はメタン酸化細菌の農業分野での安定した実用化に繋がり、農業生産の持続的な発展につながるものと考える。