Abstract：
Xanthomonas campestris strains are used world-wide for the production of the industrially important exopolysaccharide xanthan. The high industrial relevance of xanthan can be explained by its extraordinary qualities as rheological control agent in aqueous systems and by its stabilizing properties in suspensions and emulsions. The phytopathogen Xanthomonas campestris is a motile bacterium with one polar flagellum. The flagellum is a cost intensive structure, in terms of energy and building block consumption. Based on the assumption that inhibition of the flagellar biosynthesis and related proton driven motility might be beneficial for the xanthan production in Xcc, two genes (fliC and fliM) were mutated to inhibit the motility. Both mutants Xcc JBL007 fliC- and Xcc JBL007 fliM- showed an increased xanthan production. Remarkably, the produced xanthan from both mutants showed enhanced rheological properties. While the chemical composition of the produced xanthan of the initial and both mutant strains did not change, notable differences in persistence length could be measured via atomic force microscopy. Results presented in this study demonstrate the possibility to further improve the xanthan production by Xcc through rational strain design.
摘要：
Xanthomonascampestris菌株在世界范围内用于生产工业上重要的外多糖黄原胶。黄原胶的高度工业相关性可以通过其在水性体系中作为流变控制剂的非凡品质以及其在悬浮液和乳液中的稳定性能来解释。植物病原菌黄单胞菌是具有一个极性鞭毛的能动细菌。鞭毛是一种成本密集型结构，在能源和积木消耗方面。基于以下假设：抑制鞭毛生物合成和相关的质子驱动运动可能对Xcc中的黄原胶生产有益，2个基因(fliC和fliM)突变以抑制运动性。两种突变体XcCJBL007fliC-和XcCJBL007fliM-均显示黄原胶产量增加。值得注意的是,从两个突变体产生的黄原胶显示出增强的流变特性。虽然初始菌株和两种突变菌株产生的黄原胶的化学成分没有变化，可以通过原子力显微镜测量持久性长度的显着差异。这项研究的结果表明，通过合理的应变设计，进一步改善Xcc生产黄原胶的可能性。
