Formation of Highly Twisted Ribbons in a Carboxymethylcellulase Gene-Disrupted Strain of a Cellulose-Producing Bacterium

Abstract

e 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.

Identification and Characterization of Non-Cellulose-Producing Mutants of Gluconacetobacter hansenii Generated by Tn 5 Transposon Mutagenesis

“…This is similar to the cmc Ax knockout mutant of G. xylinus BPR2001 reported by Nakai et al (39). Cmc Ax is a ␤-1,4-endoglucanase (endocellulase) and has cellulose-hydrolyzing activity in vitro (13).…”

“…Cmc Ax is a ␤-1,4-endoglucanase (endocellulase) and has cellulose-hydrolyzing activity in vitro (13). Since cellulose microfibrils produced by the cmc Ax mutant are more twisted than those produced by the wild type, Nakai et al (39) suggest that cellulose-hydrolyzing activity of Cmc Ax may be required to remove distorted glucan chains during the assembly of cellulose fibrils. However, an ␤-1,4-endoglucanase alone cannot completely hydrolyze a glucan chain to glucose.…”

An Efficient Method Using Gluconacetobacter europaeus To Reduce an Unfavorable Flavor Compound, Acetoin, in Rice Vinegar Production

“…YPD was composed of 30 g/liter glucose, 5 g/liter yeast extracts (Nihon Seiyaku, Tokyo, Japan), and 2 g/liter polypeptone (Nihon Seiyaku). The minimal medium consisted of 30 2 O, and 0.5 g CoCl 2 per liter). Unless otherwise indicated, 0.4% (wt/vol) ethanol and 0.5% (wt/vol) acetic acid were added to both YPD and the minimal medium.…”

“…Several unique AAB are involved in cellulose production (2,3), symbiosis with insects (4), nitrogen fixing in the rhizosphere (5), and chronic granulomatous disease (6). Gluconacetobacter europaeus is representative of vinegar producers and is used for the production of high-acidity vinegar (acid concentration, Ͼ10%) in submerged bioreactors because it has extremely strong ethanol-oxidizing ability and ethanol/acetic acid resistance compared with other species (7).…”

Sph3 Is a Glycoside Hydrolase Required for the Biosynthesis of Galactosaminogalactan in Aspergillus fumigatus

“…In Gluconacetobacter xylinus, the carboxylmethylcellulase, CMCax, is also extracellular and is thought to be essential for cellulose assembly (21). Nakai et al (21) proposed that G. xylinus produces tangled cellulose in the absence of CMCax, which reduced the rate of synthesis and export. CMCax may clear this amorphous polymer from the synthase complex allowing for increased production (21).…”