Graduate School of Life Science, University of Hyogo, Hyogo, Japan.
J Bacteriol. 2013 Mar;195(5):958-64. doi: 10.1128/JB.01473-12. Epub 2012 Dec 14.
Cellulases are enzymes that normally digest cellulose; however, some are known to play essential roles in cellulose biosynthesis. Although some endogenous cellulases of plants and cellulose-producing bacteria are reportedly involved in cellulose production, their functions in cellulose production are unknown. In this study, we demonstrated that disruption of the cellulase (carboxymethylcellulase) gene causes irregular packing of de novo-synthesized fibrils in Gluconacetobacter xylinus, a cellulose-producing bacterium. Cellulose production was remarkably reduced and small amounts of particulate material were accumulated in the culture of a cmcax-disrupted G. xylinus strain (F2-2). The particulate material was shown to contain cellulose by both solid-state (13)C nuclear magnetic resonance analysis and Fourier transform infrared spectroscopy analysis. Electron microscopy revealed that the cellulose fibrils produced by the F2-2 cells were highly twisted compared with those produced by control cells. This hypertwisting of the fibrils may reduce cellulose synthesis in the F2-2 strains.
纤维素酶是一类能够正常消化纤维素的酶；然而，有一些已知的纤维素酶在纤维素生物合成中起着至关重要的作用。尽管一些植物和产纤维素细菌的内源性纤维素酶据称参与了纤维素的产生，但它们在纤维素产生中的功能尚不清楚。在本研究中，我们证明了纤维素酶（羧甲基纤维素酶）基因的破坏导致了产纤维素细菌木醋酸杆菌中新合成的纤维的不规则堆积。纤维素的产生显著减少，在 cmcax 敲除的 G. xylinus 菌株（F2-2）的培养物中积累了少量颗粒物质。通过固态（13）C 核磁共振分析和傅里叶变换红外光谱分析表明，该颗粒物质含有纤维素。电子显微镜显示，与对照细胞相比，F2-2 细胞产生的纤维素纤维高度扭曲。纤维的这种过度扭曲可能会降低 F2-2 菌株中的纤维素合成。
