Microbial Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands.
Microb Ecol. 2018 Aug;76(2):443-452. doi: 10.1007/s00248-017-1137-1. Epub 2018 Jan 10.
The movement of bacterial cells along with fungal hyphae in soil (the mycosphere) has been reported in several previous studies. However, how local soil conditions affect bacterial migration direction in the mycosphere has not been extensively studied. Here, we investigated the influence of two soil parameters, pH and soil moisture content, on the migration, and survival, of Paraburkholderia terrae BS001 in the mycosphere of Lyophyllum sp. strain Karsten in microcosms containing a loamy sand soil. The data showed that bacterial movement along the hyphal networks took place in both the "forward" and the "backward" directions. Low soil pH strongly restricted bacterial survival, as well as dispersal in both directions, in the mycosphere. The backward movement was weakly correlated with the amount of fungal tissue formed in the old mycelial network. The initial soil moisture content, set at 12 versus 17% (corresponding to 42 and 60% of the soil water holding capacity), also significantly affected the bacterial dispersal along the fungal hyphae. Overall, the presence of fungal hyphae was found to increase the soil pH (under conditions of acidity), which possibly exerted protective effects on the bacterial cells. Finally, we provide a refined model that describes the bacterial migration patterns with fungal hyphae based on the new findings in this study.
已有几项先前的研究报告指出，细菌细胞会沿着土壤中的真菌菌丝（菌根圈）移动。然而，局部土壤条件如何影响菌根圈内细菌的迁移方向尚未得到广泛研究。在这里，我们研究了两种土壤参数，即 pH 值和土壤含水量，对蜡蘑菌株 Karsten 菌根圈内 Paraburkholderia terrae BS001 迁移和存活的影响，该菌根圈存在于砂壤土的微生境中。数据表明，细菌沿着菌丝网络的移动在“向前”和“向后”两个方向都发生了。低土壤 pH 值强烈限制了细菌在菌根圈内的生存和两个方向的扩散。向后的运动与旧菌丝网络中形成的真菌组织量呈弱相关。初始土壤含水量设定为 12%与 17%（分别对应于土壤持水量的 42%和 60%），也显著影响了细菌沿真菌菌丝的扩散。总的来说，发现真菌菌丝的存在会增加土壤 pH 值（在酸性条件下），这可能对细菌细胞产生保护作用。最后，我们根据本研究的新发现，提供了一个描述细菌与真菌菌丝迁移模式的改进模型。
