大肠杆菌生物膜关键组分缺失对细胞性能的影响

Absence of Key Biofilm Components Affect Cell Performances in Escherichia coli

摘要:

大肠杆菌胞外存在复杂且种类繁多的生物膜组分，这些生物膜组分不仅在合成和组装过程中耗费大量的能源和底物，且某些组分还存在巨大的致病风险。为减少这些不利影响，作者采用Crisp-Cas9基因编辑技术，从基因水平分别去除大肠杆菌MG1655中非必需生物膜组分，构建了一系列非必需生物膜组分缺失突变菌株。对突变株的细胞特性进行考察，筛选具有优异特性的突变菌株。结果显示，敲除鞭毛fliE-R、fliY-T、flhE-D 、4型荚膜、唾液酸和聚- β-1,6-葡萄糖胺基因簇能促进菌株在M9培养基中的生长；敲除鞭毛基因簇flgN-L和胞外多糖类组分有利于PHB合成；敲除胞外多糖类组分基因簇或鞭毛的4个基因簇，能增强菌株膜通透性；去除大肠杆菌核心多糖能重塑代谢调控，促进克拉酸的生产。

Abstract:

Escherichia coli possesses a complex and diverse array of extracellular biofilm components. These biomolecules not only consume a large amount of energy and substrates during their synthesis and assembly, but certain components also present huge risks for pathogenicity. In order to mitigate the adverse effects, Crisp-Cas9 gene-editing method was employed to remove non-essentia biofilm components from Escherichia coli MG1655 at the genetic level. A series of mutant strains with deleted non-essential biofilm components were constructed, and the cellular characteristics of these mutant strains were investigated to identify those with superior performances. The results showed that knockout of genes encoding flagellum(fliE-R, fliY-T , and flhE-D ), type 4 capsule, sialic acid and poly- β-1,6-glucosamine could promote the growth of mutants in M9 medium. Deletion of flagellar gene clusters flgN-L and exopolysaccharide components enhanced PHB synthesis, while knocking out four gene clusters related to extracellular polysaccharide components or flagella could enhance the membrane permeability. The removal of core polysaccharides from Escherichia coli could remodel metabolic regulation and promote the production of colanic acid.