School of Biology, University of Nottingham, Nottingham, United Kingdom.
PLoS One. 2013 Dec 6;8(12):e81549. doi: 10.1371/journal.pone.0081549. eCollection 2013.
Response to mechanical force is a well characterised phenomenon in eukaryotic organisms, helping to organise multicellular structures. Mechanotactic responses have only rarely been observed in prokaryotic taxa. This work reports on a morphological change due to variations in applied force and surface structure by Bacillus mycoides Flügge. B. mycoides is a ubiquitous soil organism well known among microbiologists for its characteristic spreading colony morphology. An apparent mechanotactic response is elicited by physical deformation of the gel media on which B.mycoides is growing, including applied forces of compression or tension. Variations in the surface such as curvature produced by casting the agar gel in the presence of curved objects also elicited the change. The morphological change in B.mycoides colonies associated with the application of force manifests as a pattern of parallel rhizoid filaments perpendicular to compressing force and parallel to stretching force in the agar medium. The phenomenon is most clearly demonstrated by reversible changes in the orientation of B. mycoides filaments during time-lapse microscopy.
对机械力的反应是真核生物中一种特征明显的现象，有助于组织多细胞结构。原核生物类群中很少观察到趋机械性反应。本研究报告了由于施加的力和表面结构的变化而导致的粘质沙雷氏菌形态变化。粘质沙雷氏菌是一种无处不在的土壤生物，因其特征性的蔓延菌落形态而在微生物学家中广为人知。在粘质沙雷氏菌生长的凝胶培养基上施加物理变形，包括压缩或拉伸力，会引起明显的趋机械性反应。在存在弯曲物体的情况下铸造琼脂凝胶时产生的表面曲率等变化也会引起这种变化。与力的施加相关的粘质沙雷氏菌菌落的形态变化表现为与琼脂培养基中的压缩力垂直且与拉伸力平行的平行根状丝的模式。通过延时显微镜观察到粘质沙雷氏菌丝的方向可逆变化，最清楚地证明了这一现象。
