Accumulation of Cello-oligosaccharides during Bacterial Cellulose Production by Acetobacter xylinum

Abstract

Acetobacter xylinum has been used for many years as a model system for the study of cellulose biosynthesis. Interestingly, in addition to cellulose biosynthesis, this bacterium has also produced cellulolytic enzymes. 1) However, the relation between the two products has not been made clear. Furthermore, it is reported that some strains of Acetobacter have accumulated a water soluble polysaccharide called acetan, 2) which has a similar structure to xanthan. 3,4) Cellulose is an insoluble 1,4 glucan, but acetan is a soluble sugar, which has the same backbone as cellulose. Furthermore it has attached side chain composed of glucose, mannose, glucuronic acid and rhamnose and the composition of those sugars is 4:1:1:1 (glucose:mannose: glucuronic acid : rhamnose). It was reported that Acetobacter acetigenum produced various carbohydrates, cellobiose, cellotriose, cellotetraose and fructose growing in a defined medium containing glucose. 5) Valla et al. 6) have shown a new extracellular polysaccharide from a cellulose negative strain of A. xylinum ATCC10245. In that report they showed that the polysaccharide contains glucose, mannose, rhamnose, and glucuronic acid in a molar ratio approximating 3:1:1:1. Partial acid hydrolysis results in release of glucose, rhamnose, and a disaccharide consisting of two glucose units. They speculated that this disaccharide might be gentiobiose, but the origin of these sugars has not been clarified. We also detected gentiobiose and various cello oligosaccharides in the culture broth of A. xylinum. In this paper we discuss what has been the real origin of various cello oligosaccharides synthesized during culture. First, the sugars produced in the Hestrin and Schramm (SH) 7) medium during the static culture of A. xylinum

Investigation of Bacterial Cellulose Biosynthesis Mechanism inGluconoacetobacter hansenii

“…In cellulase hydrolysis assay, glucose liberated from cellulose was quantified by Millers method with dinitrosalicylic acid which specifically reacts with the free sugar. The concentration of reducing sugar after cellulase hydrolysis was much higher (115 μ g/mL) compared with unhydrolyzed reaction product [ 25 ]. The positive cellulase assay confirmed that the substrate for cellulase assay was of polymeric β -1,4-glucan nature.…”