Bacteria with natural chemotaxis towards methanol revealed by chemotaxis fishing technique

Motile bacteria often exhibit chemotaxis toward favorable compounds. However, the diversity of bacteria that are attracted to a given substance is largely unknown. This study aimed to reveal the diversity of bacteria with natural chemotaxis towards methanol. We tried to enrich environmental chemotactic bacteria using a glass capillary that is half-filled with methanol solidified with agarose as a trap (“chemotaxis fishing”). The pilot experiment using methanol-chemotactic <i>Methylobacterium aquaticum</i> strain 22A enriched the cells by 46-fold. The method was then applied to bacterial suspensions from paddy water and plants. Depending on the isolation sources and the methods of motility induction, methylotrophic bacteria were enriched 1.2–330-fold. The fished isolates belong to 32 species in 18 genera, mainly containing <i>Acinetobacter, Methylobacterium</i> and <i>Pseudomonas</i> species. Our chemotaxis fishing unveiled a part of diversity of the bacteria with natural chemotaxis towards methanol. A glass capillary containing methanol was used as a trap to enrich methanol-chemotactic bacteria.

具有运动能力的细菌通常会向有益化合物表现出趋化性（chemotaxis）。然而，可被特定物质吸引的细菌类群多样性在很大程度上仍未被充分认知。本研究旨在揭示对甲醇具有天然趋化性的细菌类群多样性。我们尝试采用半填充以琼脂糖（agarose）固化甲醇的玻璃毛细管作为捕获装置（命名为"趋化垂钓法"），以富集环境中的趋化性细菌。以具甲醇趋化性的水生甲基杆菌（*Methylobacterium aquaticum*）菌株22A开展预实验，实现了46倍的菌体富集。随后将该方法应用于稻田水体及植物来源的细菌悬浮液，根据分离来源及运动性诱导方式的不同，甲基营养型细菌的富集倍数可达1.2~330倍。经该方法捕获的分离菌株隶属于18个属的32个物种，主要包含不动杆菌属（*Acinetobacter*）、甲基杆菌属（*Methylobacterium*）及假单胞菌属（*Pseudomonas*）的物种。本研究建立的趋化垂钓法，揭示了部分对甲醇具有天然趋化性的细菌类群多样性。本方法通过装填甲醇的玻璃毛细管作为捕获装置，实现甲醇趋化性细菌的富集。