Ritchie Linnea J, Curtis Erin R, Murphy Kimberly A, Welch Roy D
Department of Biology, Syracuse Universitygrid.264484.8, Syracuse, New York, USA.
Department of Biology, Augustana College, Rock Island, Illinois, USA.
J Bacteriol. 2021 Nov 5;203(23):e0030621. doi: 10.1128/JB.00306-21. Epub 2021 Sep 20.
Myxococcus xanthus is a bacterium that lives on surfaces as a predatory biofilm called a swarm. As a growing swarm feeds on prey and expands, it displays dynamic multicellular patterns such as traveling waves called ripples and branching protrusions called flares. The rate at which a swarm expands across a surface, and the emergence of the coexisting patterns, are all controlled through coordinated cell movement. M. xanthus cells move using two motility systems known as adventurous (A) and social (S). Both are involved in swarm expansion and pattern formation. In this study, we describe a set of M. xanthus swarming genotype-to-phenotype associations that include both genetic and environmental perturbations. We identified new features of the swarming phenotype, recorded and measured swarm expansion using time-lapse microscopy, and compared the impact of mutations on different surfaces. These observations and analyses have increased our ability to discriminate between swarming phenotypes and provided context that allows us to identify some phenotypes as improbable outliers within the M. xanthus swarming phenome. Myxococcus xanthus grows on surfaces as a predatory biofilm called a swarm. In nature, a feeding swarm expands by moving over and consuming prey bacteria. In the laboratory, a swarm is created by spotting cell suspension onto nutrient agar in lieu of prey. The suspended cells quickly settle on the surface as the liquid is absorbed into the agar, and the new swarm then expands radially. An assay that measures the expansion rate of a swarm of mutant cells is the first, and sometimes only, measurement used to decide whether a particular mutation impacts swarm motility. We have broadened the scope of this assay by increasing the accuracy of measurements and introducing prey, resulting in new identifiable and quantifiable features that can be used to improve genotype-to-phenotype associations.
黄色粘球菌是一种以称为群体的掠食性生物膜形式生活在表面的细菌。随着不断生长的群体以猎物为食并扩张，它会呈现出动态的多细胞模式，如称为涟漪的行波和称为耀斑的分支突起。群体在表面上扩张的速度以及共存模式的出现，都通过细胞的协调运动来控制。黄色粘球菌细胞利用两种运动系统移动，即冒险性（A）运动系统和社会性（S）运动系统。这两种运动系统都参与群体扩张和模式形成。在本研究中，我们描述了一组黄色粘球菌群体基因型与表型的关联，其中包括遗传和环境扰动。我们确定了群体表型的新特征，使用延时显微镜记录并测量了群体扩张，并比较了突变在不同表面上的影响。这些观察和分析提高了我们区分群体表型的能力，并提供了相关背景，使我们能够将某些表型识别为黄色粘球菌群体表型组中不太可能出现的异常值。黄色粘球菌以称为群体的掠食性生物膜形式在表面生长。在自然界中，觅食的群体通过在猎物上移动并消耗猎物细菌来扩张。在实验室中，通过将细胞悬液点涂到营养琼脂上以代替猎物来创建群体。随着液体被琼脂吸收，悬浮的细胞迅速在表面沉降，然后新的群体径向扩张。测量突变细胞群体扩张速率的测定法是用于确定特定突变是否影响群体运动性的首个（有时也是唯一的）测量方法。我们通过提高测量精度并引入猎物来拓宽了该测定法的范围，从而产生了新的可识别和可量化的特征，可用于改善基因型与表型的关联。
