Accumulation and spread dynamics of antimicrobial-resistant bacteria in seabirds through food web

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K12272
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63040:Environmental impact assessment-related
• Research Institution: Setsunan University (2023); Osaka Ohtani University (2021-2022)
• Principal Investigator: Takehiko Kenzaka 摂南大学, 理工学部, 教授 (80397661)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 抗菌薬耐性 / 海鳥 / カモメ / 生物濃縮 / コリスチン / 大腸菌 / 渡り鳥

Outline of Final Research Achievements

Using a combination of metagenomic methods with high-throughput DNA sequencers and cultivation techniques, I comprehensively examined the presence of resistant bacteria and genes in the intestines of seabirds (Slaty-backed Gulls and Black-tailed Gulls), prey organisms at different trophic levels, and seawater at the breeding sites in Hokkaido. This was done to verify the concentration mechanisms of resistant bacteria through food web. Colistin-resistant Escherichia coli and the colistin-resistant gene mcr-1 were not detected in zooplankton, marine organisms, or seawater. However, they were found in 20% and 35% of Black-tailed Gulls and Slaty-backed Gulls, respectively. The diet consumed varied by season and year, and specific diet organisms were identified as increasing factors for the biomagnification of mcr-1.

Free Research Field

分子生態学

Academic Significance and Societal Importance of the Research Achievements

渡り性のカモメであるオオセグロカモメとウミネコでは、特定の餌生物を摂取することで、コリスチン耐性菌や耐性遺伝子が腸内に濃縮され、繁殖期には20-35%の割合で耐性遺伝子を保有していることが明らかとなった。カモメは繁殖期に採餌行動で数十km、渡り期には千km以上移動し、糞とともに耐性菌や耐性遺伝子を海水中に放出する。本研究により、食物連鎖を介した耐性菌の濃縮・移動の実態の一部が明らかになり、地理的に離れた地域で類似の耐性菌が発見される要因として、渡り性のカモメが重要であることが示された。本研究は、環境中に潜む抗菌薬耐性菌が地球規模で蔓延する機構の解明に寄与するものである。