Dergham Yasmine, Sanchez-Vizuete Pilar, Le Coq Dominique, Deschamps Julien, Bridier Arnaud, Hamze Kassem, Briandet Romain
Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
Faculty of Science, Lebanese University, 1003 Beirut, Lebanon.
Microorganisms. 2021 Mar 18;9(3):633. doi: 10.3390/microorganisms9030633.
Surface-associated multicellular assemblage is an important bacterial trait to withstand harsh environmental conditions. is one of the most studied Gram-positive bacteria, serving as a model for the study of genetic pathways involved in the different steps of 3D biofilm formation. biofilm studies have mainly focused on pellicle formation at the air-liquid interface or complex macrocolonies formed on nutritive agar. However, only few studies focus on the genetic features of submerged biofilm formation and their link with other multicellular models at the air interface. NDmed, an undomesticated strain isolated from a hospital, has demonstrated the ability to produce highly structured immersed biofilms when compared to strains classically used for studying biofilms. In this contribution, we have conducted a multi-culturing comparison (between macrocolony, swarming, pellicle, and submerged biofilm) of multicellular communities using the NDmed strain and mutated derivatives for genes shown to be required for motility and biofilm formation in pellicle and macrocolony models. For the 15 mutated NDmed strains studied, all showed an altered phenotype for at least one of the different culture laboratory assays. Mutation of genes involved in matrix production (i.e., , , , ) caused a negative impact on all biofilm phenotypes but favored swarming motility on semi-solid surfaces. Mutation of , a gene coding for an amphiphilic protein, affected the stability of the pellicle at the air-liquid interface with no impact on the submerged biofilm model. Moreover, mutation of an autolysin gene required for cell separation, had a greater effect on the submerged biofilm model than that formed at aerial level, opposite to the observation for mutant. In addition, NDmed with mutation formed wrinkled macrocolony, less than that formed by the wild type, but was unable to form neither thick pellicle nor structured submerged biofilm. The results are discussed in terms of the relevancy to determine whether genes involved in colony and pellicle formation also govern submerged biofilm formation, by regarding the specificities in each model.
表面相关的多细胞聚集体是细菌抵御恶劣环境条件的重要特性。是研究最多的革兰氏阳性菌之一,作为研究参与三维生物膜形成不同步骤的遗传途径的模型。生物膜研究主要集中在气液界面的菌膜形成或营养琼脂上形成的复杂大菌落。然而,只有少数研究关注水下生物膜形成的遗传特征及其与气界面其他多细胞模型的联系。NDmed是从一家医院分离出的未驯化菌株,与经典用于研究生物膜的菌株相比,它已证明有能力产生高度结构化的浸没生物膜。在本论文中,我们使用NDmed菌株及其在菌膜和大菌落模型中被证明对运动性和生物膜形成必需的基因的突变衍生物,对多细胞群落进行了多种培养比较(大菌落、群体游动、菌膜和浸没生物膜之间)。对于所研究的15个突变NDmed菌株,所有菌株在至少一种不同的培养实验室测定中都表现出改变的表型。参与基质产生的基因(即、、、)的突变对所有生物膜表型都有负面影响,但有利于在半固体表面的群体游动。编码两亲性蛋白的基因的突变影响了气液界面菌膜的稳定性,对浸没生物膜模型没有影响。此外,细胞分离所需的自溶素基因的突变对浸没生物膜模型的影响比对气生水平形成的生物膜模型的影响更大,这与突变体的观察结果相反。此外,具有突变的NDmed形成的皱缩大菌落比野生型形成的少,但既不能形成厚菌膜也不能形成结构化的浸没生物膜。通过考虑每个模型的特异性,就确定参与菌落和菌膜形成的基因是否也控制浸没生物膜形成的相关性对结果进行了讨论。