Cooper Vaughn S, Staples Rachel K, Traverse Charles C, Ellis Crystal N
Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH 03820, USA.
Department of Biology and Biochemistry, University of Houston, Houston, TX, USA.
Genomics. 2014 Dec;104(6 Pt A):447-52. doi: 10.1016/j.ygeno.2014.09.007. Epub 2014 Sep 28.
A common phenotype within bacterial biofilms is the small, "wrinkly" colony, which may associate with worse prognoses from biofilm-associated infections. The mechanisms that produce these variants in Burkholderia are undefined. Here we report the mutational and ecological causes of wrinkly (W) colonies that evolved during experimental biofilm evolution of Burkholderia cenocepacia. Mutations clustered in a homologous pathway to the Pseudomonas wsp operon but with a distinct terminal signaling mechanism, and their parallel evolution suggested that they inhabited an equivalent biofilm niche. We tested this hypothesis of niche complementarity by measuring effects of substituting different W variants in the same evolved biofilm community. Despite phenotypic differences among W mutants growing alone, fitness of reconstituted mixed biofilms did not differ significantly. In conclusion, the evolution of small-colony variants in Burkholderia biofilms appears to be driven by an ecological opportunity that generates strong selection for constitutive wsp mutants to inhabit a common niche.
细菌生物膜中的一种常见表型是小的“皱缩”菌落，这可能与生物膜相关感染的较差预后有关。在伯克霍尔德菌中产生这些变体的机制尚不清楚。在此，我们报告了在洋葱伯克霍尔德菌实验性生物膜进化过程中出现的皱缩（W）菌落的突变和生态原因。突变集中在与铜绿假单胞菌wsp操纵子同源的途径中，但具有独特的终端信号机制，并且它们的平行进化表明它们占据了等效的生物膜生态位。我们通过测量在同一进化的生物膜群落中替换不同W变体的影响来检验这种生态位互补性的假设。尽管单独生长的W突变体之间存在表型差异，但重组混合生物膜的适应性没有显著差异。总之，伯克霍尔德菌生物膜中小菌落变体的进化似乎是由一种生态机会驱动的，这种机会对组成型wsp突变体占据共同生态位产生了强烈选择。
