Warmink J A, van Elsas J D
Department of Microbial Ecology, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9750RA Haren, The Netherlands.
Appl Environ Microbiol. 2009 May;75(9):2820-30. doi: 10.1128/AEM.02110-08. Epub 2009 Mar 13.
In this study, the selection of bacteria on the basis of their migration via fungal hyphae in soil was investigated in microcosm experiments containing Lyophyllum sp. strain Karsten (DSM2979). One week following inoculation with a bacterial community obtained from soil, selection of a few specific bacterial types was noticed at 30 mm in the growth direction of Lyophyllum sp. strain Karsten in sterile soil. Cultivation-based analyses showed that the migration-proficient types encompassed 10 bacterial groups, as evidenced by (GTG)(5) genomic fingerprinting as well as 16S rRNA gene sequencing. These were (>97% similarity) Burkholderia terrae BS001, Burkholderia sordidicola BS026, Burkholderia sediminicola BS010, and Burkholderia phenazinium BS028; Dyella japonica BS013, BS018, and BS021; "Sphingoterrabacterium pocheensis" BS024; Sphingobacterium daejeonense BS025; and Ralstonia basilensis BS017. Migration as single species was subsequently found for B. terrae BS001, D. japonica BS018 and BS021, and R. basilensis BS017. Typically, migration occurred only when these organisms were introduced at the fungal growth front and only in the direction of hyphal growth. Migration proficiency showed a one-sided correlation with the presence of the hrcR gene, used as a marker for the type III secretion system (TTSS), as all single-strain migrators were equipped with this system and most non-single-strain migrators were not. The presence of the TTSS stood in contrast to the low prevalence of TTSSs within the bacterial community used as an inoculum (<3%). Microscopic examination of B. terrae BS001 in contact with Lyophyllum sp. strain Karsten hyphae revealed the development of a biofilm surrounding the hyphae. Migration-proficient bacteria interacting with Lyophyllum sp. strain Karsten may show complex behavior (biofilm formation) at the fungal tip, leading to their translocation and growth in novel microhabitats in soil.
在本研究中，我们在含有卡氏离褶伞（DSM2979）的微观实验中，研究了基于细菌在土壤中通过真菌菌丝迁移情况来进行细菌筛选。用从土壤中获得的细菌群落接种一周后，在无菌土壤中卡氏离褶伞生长方向30毫米处，发现了几种特定细菌类型的筛选现象。基于培养的分析表明，迁移能力强的类型包括10个细菌类群，(GTG)₅基因组指纹图谱以及16S rRNA基因测序都证明了这一点。这些细菌类群（相似度>97%）包括：土壤伯克霍尔德菌BS001、恶臭伯克霍尔德菌BS026、沉积物伯克霍尔德菌BS010、吩嗪伯克霍尔德菌BS028；日本戴氏菌BS013、BS018和BS021；“波氏鞘脂土杆菌”BS024；大田鞘氨醇杆菌BS025；以及罗尔斯通氏菌BS017。随后发现土壤伯克霍尔德菌BS001、日本戴氏菌BS018和BS021以及罗尔斯通氏菌BS017能够以单一物种形式迁移。通常情况下，只有当这些生物体被引入到真菌生长前沿且仅沿菌丝生长方向时才会发生迁移。迁移能力与用作III型分泌系统（TTSS）标记的hrcR基因的存在呈单向相关性，因为所有单一菌株迁移者都具备该系统，而大多数非单一菌株迁移者则没有。TTSS的存在与用作接种物的细菌群落中TTSS的低流行率（<3%）形成对比。对与卡氏离褶伞菌丝接触的土壤伯克霍尔德菌BS001进行显微镜检查发现，菌丝周围形成了生物膜。与卡氏离褶伞相互作用的迁移能力强的细菌可能在真菌尖端表现出复杂行为（生物膜形成），从而导致它们在土壤中的新微生境中转移和生长。
