自閉症スペクトラム障害に関連するプロピオン酸菌の単離、同定および特徴付け

Isolation, identification and characterization of propionic acid bacteria associated with autistic spectrum disorder.

• Rongrong Yu
• Zhifeng Wu
• Shuhui Wang
• Muchen Zhang
• Guoling Zhou
• Bin Li

抄録

自閉症スペクトラム障害（ASD）は、子どもたちの健康に深刻な影響を与えます。近年、プロピオン酸（PA）がASDの形成に重要な役割を果たすことが報告されている。本研究では、健常児とASD児のPA関連細菌の分離・培養による群集構造を調べ、代表的なPA関連細菌群をコロニー形態観察、生理学的・生化学的検査、生死細胞染色分析、16S rRNA遺伝子配列決定などに基づいて同定・特徴付けを行った。その結果、健常児のPA関連菌数はASD児の100倍以上であったが、ASD児のPA関連菌は健常児に比べて多様性が高いことが明らかになった。代表的な菌株のPAに対する感受性は，菌種，PA濃度，培養時間の影響を受けた。また，PA耐性菌であるLactobacillus plantarum 6-1株ではpH値の低下が認められたが，PA感受性菌であるEnterococcus lactis 4-1株ではpH値の低下は認められず，両菌のバイオフィルム形成はPAの影響を受けていなかった．さらに、PAは選択された2つの菌株の増殖を抑制したが、菌株4-1ではより大きな抑制効果が観察された。以上の結果は、ASD発症におけるPA関連細菌の役割を明らかにする上で大きな意義があると考えられた。

Autism spectrum disorder (ASD) seriously affects children's health. Recently, propionic acid (PA) has been reported to play a significant role in the formation of ASD. In this study, we investigated the community structure of PA-related bacteria in healthy and ASD children by isolation and culture, while a group of representative PA-related bacteria were identified and characterized based on colony morphological observation, physiological and biochemical tests, as well as living/dead cells staining analysis and 16S rRNA gene sequencing. The results showed that the number of PA-related bacteria in healthy children was >100-fold higher than that in ASD children, while compared to healthy children, greater diversity was found in PA-associated bacteria from ASD children. The sensitivity of the representative strains to PA was affected by bacterial species, PA concentration and incubation time. The decrease of pH value was found in PA-resistant Lactobacillus plantarum strain 6-1 but not in PA-sensitive Enterococcus lactis strain 4-1, while biofilm formation of both strains were unaffected by PA. Furthermore, PA inhibited the propagation of the two selected bacteria rather than killed them, while the greater inhibitory effect was observed on strain 4-1. Overall, the result is of great significance for revealing the role of PA-related bacteria in development of ASD.

Copyright © 2020. Published by Elsevier Ltd.